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• Why does fprintf start printing out of order or not at all?

  - by Steve Melvin

  This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas? #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #define WRITE 1 #define READ 0 int main (int argc, const char * argv[]) { //Pipe file-descriptor array unsigned int isChildA = 0; int pipeA[2]; int pipeB[2]; int num = 0; while(1){ fprintf(stderr,"Enter an integer: "); scanf("%i", &num); if(num == 0){ fprintf(stderr,"You entered zero, exiting...\n"); exit(0); } //Open Pipes if(pipe(pipeA) < 0){ fprintf(stderr,"Could not create pipe A.\n"); exit(1); } if(pipe(pipeB) < 0){ fprintf(stderr,"Could not create pipe B.\n"); exit(1); } fprintf(stderr,"Value read: %i \n", num); fprintf(stderr,"Parent PID: %i\n", getpid()); pid_t procID = fork(); switch (procID) { case -1: fprintf(stderr,"Fork error, quitting...\n"); exit(1); break; case 0: isChildA = 1; break; default: procID = fork(); if (procID<0) { fprintf(stderr,"Fork error, quitting...\n"); exit(1); } else if(procID == 0){ isChildA = 0; } else { write(pipeA[WRITE], &num, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); pid_t pid; while (pid = waitpid(-1, NULL, 0)) { if (errno == ECHILD) { break; } } } break; } if (procID == 0) { //We're a child, do kid-stuff. ssize_t bytesRead = 0; int response; while (1) { while (bytesRead == 0) { bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int)); } if (response < 2) { //Kill other child and self fprintf(stderr, "Terminating PROCID: %i\n", getpid()); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); return 0; } else if(!(response%2)){ //Even response/=2; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } else { //Odd response*=3; response++; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } } } } return 0; } This is the output I am getting... bash-3.00$ ./proj2 Enter an integer: 101 Value read: 101 Parent PID: 9379 PROCID: 9380, VALUE: 304 PROCID: 9381, VALUE: 152 PROCID: 9380, VALUE: 76 PROCID: 9381, VALUE: 38 PROCID: 9380, VALUE: 19 PROCID: 9381, VALUE: 58 PROCID: 9380, VALUE: 29 PROCID: 9381, VALUE: 88 PROCID: 9380, VALUE: 44 PROCID: 9381, VALUE: 22 PROCID: 9380, VALUE: 11 PROCID: 9381, VALUE: 34 PROCID: 9380, VALUE: 17 PROCID: 9381, VALUE: 52 PROCID: 9380, VALUE: 26 PROCID: 9381, VALUE: 13 PROCID: 9380, VALUE: 40 PROCID: 9381, VALUE: 20 PROCID: 9380, VALUE: 10 PROCID: 9381, VALUE: 5 PROCID: 9380, VALUE: 16 PROCID: 9381, VALUE: 8 PROCID: 9380, VALUE: 4 PROCID: 9381, VALUE: 2 PROCID: 9380, VALUE: 1 Terminating PROCID: 9381 Terminating PROCID: 9380 Enter an integer: 102 Value read: 102 Parent PID: 9379 PROCID: 9386, VALUE: 51 PROCID: 9387, VALUE: 154 PROCID: 9386, VALUE: 77 PROCID: 9387, VALUE: 232 PROCID: 9386, VALUE: 116 PROCID: 9387, VALUE: 58 PROCID: 9386, VALUE: 29 PROCID: 9387, VALUE: 88 PROCID: 9386, VALUE: 44 PROCID: 9387, VALUE: 22 PROCID: 9386, VALUE: 11 PROCID: 9387, VALUE: 34 PROCID: 9386, VALUE: 17 PROCID: 9387, VALUE: 52 PROCID: 9386, VALUE: 26 PROCID: 9387, VALUE: 13 PROCID: 9386, VALUE: 40 PROCID: 9387, VALUE: 20 PROCID: 9386, VALUE: 10 PROCID: 9387, VALUE: 5 PROCID: 9386, VALUE: 16 PROCID: 9387, VALUE: 8 PROCID: 9386, VALUE: 4 PROCID: 9387, VALUE: 2 PROCID: 9386, VALUE: 1 Terminating PROCID: 9387 Terminating PROCID: 9386 Enter an integer: 104 Value read: 104 Parent PID: 9379 Enter an integer: PROCID: 9388, VALUE: 52 PROCID: 9389, VALUE: 26 PROCID: 9388, VALUE: 13 PROCID: 9389, VALUE: 40 PROCID: 9388, VALUE: 20 PROCID: 9389, VALUE: 10 PROCID: 9388, VALUE: 5 PROCID: 9389, VALUE: 16 PROCID: 9388, VALUE: 8 PROCID: 9389, VALUE: 4 PROCID: 9388, VALUE: 2 PROCID: 9389, VALUE: 1 Terminating PROCID: 9388 Terminating PROCID: 9389 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9395, VALUE: 316 PROCID: 9396, VALUE: 158 PROCID: 9395, VALUE: 79 PROCID: 9396, VALUE: 238 PROCID: 9395, VALUE: 119 PROCID: 9396, VALUE: 358 PROCID: 9395, VALUE: 179 PROCID: 9396, VALUE: 538 PROCID: 9395, VALUE: 269 PROCID: 9396, VALUE: 808 PROCID: 9395, VALUE: 404 PROCID: 9396, VALUE: 202 PROCID: 9395, VALUE: 101 PROCID: 9396, VALUE: 304 PROCID: 9395, VALUE: 152 PROCID: 9396, VALUE: 76 PROCID: 9395, VALUE: 38 PROCID: 9396, VALUE: 19 PROCID: 9395, VALUE: 58 PROCID: 9396, VALUE: 29 PROCID: 9395, VALUE: 88 PROCID: 9396, VALUE: 44 PROCID: 9395, VALUE: 22 PROCID: 9396, VALUE: 11 PROCID: 9395, VALUE: 34 PROCID: 9396, VALUE: 17 PROCID: 9395, VALUE: 52 PROCID: 9396, VALUE: 26 PROCID: 9395, VALUE: 13 PROCID: 9396, VALUE: 40 PROCID: 9395, VALUE: 20 PROCID: 9396, VALUE: 10 PROCID: 9395, VALUE: 5 PROCID: 9396, VALUE: 16 PROCID: 9395, VALUE: 8 PROCID: 9396, VALUE: 4 PROCID: 9395, VALUE: 2 PROCID: 9396, VALUE: 1 Terminating PROCID: 9395 Terminating PROCID: 9396 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9397, VALUE: 316 PROCID: 9398, VALUE: 158 PROCID: 9397, VALUE: 79 PROCID: 9398, VALUE: 238 PROCID: 9397, VALUE: 119 PROCID: 9398, VALUE: 358 PROCID: 9397, VALUE: 179 PROCID: 9398, VALUE: 538 PROCID: 9397, VALUE: 269 PROCID: 9398, VALUE: 808 PROCID: 9397, VALUE: 404 PROCID: 9398, VALUE: 202 PROCID: 9397, VALUE: 101 PROCID: 9398, VALUE: 304 PROCID: 9397, VALUE: 152 PROCID: 9398, VALUE: 76 PROCID: 9397, VALUE: 38 PROCID: 9398, VALUE: 19 PROCID: 9397, VALUE: 58 PROCID: 9398, VALUE: 29 PROCID: 9397, VALUE: 88 PROCID: 9398, VALUE: 44 PROCID: 9397, VALUE: 22 PROCID: 9398, VALUE: 11 PROCID: 9397, VALUE: 34 PROCID: 9398, VALUE: 17 PROCID: 9397, VALUE: 52 PROCID: 9398, VALUE: 26 PROCID: 9397, VALUE: 13 PROCID: 9398, VALUE: 40 PROCID: 9397, VALUE: 20 PROCID: 9398, VALUE: 10 PROCID: 9397, VALUE: 5 PROCID: 9398, VALUE: 16 PROCID: 9397, VALUE: 8 PROCID: 9398, VALUE: 4 PROCID: 9397, VALUE: 2 PROCID: 9398, VALUE: 1 Terminating PROCID: 9397 Terminating PROCID: 9398 106 Value read: 106 Parent PID: 9379 Enter an integer: PROCID: 9399, VALUE: 53 PROCID: 9400, VALUE: 160 PROCID: 9399, VALUE: 80 PROCID: 9400, VALUE: 40 PROCID: 9399, VALUE: 20 PROCID: 9400, VALUE: 10 PROCID: 9399, VALUE: 5 PROCID: 9400, VALUE: 16 PROCID: 9399, VALUE: 8 PROCID: 9400, VALUE: 4 PROCID: 9399, VALUE: 2 PROCID: 9400, VALUE: 1 Terminating PROCID: 9399 Terminating PROCID: 9400 ^C Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.

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• XSL Template outputting massive chunk of text, rather than HTML. But only on one section

  - by Throlkim

  I'm having a slightly odd situation with an XSL template. Most of it outputs fine, but a certain for-each loop is causing me problems. Here's the XML: <area> <feature type="Hall"> <Heading><![CDATA[Hall]]></Heading> <Para><![CDATA[Communal gardens, pathway leading to PVCu double glazed communal front door to]]></Para> </feature> <feature type="Entrance Hall"> <Heading><![CDATA[Communal Entrance Hall]]></Heading> <Para><![CDATA[Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to]]></Para> </feature> <feature type="Inner Hall"> <Heading><![CDATA[Inner Hall]]></Heading> <Para><![CDATA[Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms.]]></Para> </feature> <feature type="Lounge (Reception)" width="3.05" length="4.57" units="metre"> <Heading><![CDATA[Lounge (Reception)]]></Heading> <Para><![CDATA[15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point.]]></Para> </feature> <feature type="Kitchen" width="3.05" length="3.66" units="metre"> <Heading><![CDATA[Kitchen]]></Heading> <Para><![CDATA[12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points.]]></Para> </feature> <feature type="Entrance Porch"> <Heading><![CDATA[Balcony]]></Heading> <Para><![CDATA[Views across the communal South facing garden, wrought iron balustrade.]]></Para> </feature> <feature type="Bedroom" width="3.35" length="3.96" units="metre"> <Heading><![CDATA[Bedroom One]]></Heading> <Para><![CDATA[13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone.]]></Para> </feature> <feature type="Bedroom" width="3.05" length="3.35" units="metre"> <Heading><![CDATA[Bedroom Two]]></Heading> <Para><![CDATA[11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points.]]></Para> </feature> <feature type="bathroom"> <Heading><![CDATA[Bathroom]]></Heading> <Para><![CDATA[Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks.]]></Para> </feature> </area> And here's the section of my template that processes it: <xsl:for-each select="area"> <li> <xsl:for-each select="feature"> <li> <h5> <xsl:value-of select="Heading"/> </h5> <xsl:value-of select="Para"/> </li> </xsl:for-each> </li> </xsl:for-each> And here's the output: Hall Communal gardens, pathway leading to PVCu double glazed communal front door to Communal Entrance Hall Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to Inner Hall Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms. Lounge (Reception) 15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point. Kitchen 12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points. Balcony Views across the communal South facing garden, wrought iron balustrade. Bedroom One 13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone. Bedroom Two 11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points. Bathroom Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks. For reference, here's the entire XSLT: http://pastie.org/private/eq4gjvqoc1amg9ynyf6wzg The rest of it all outputs fine - what am I missing from the above section?

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• Issues passing values to shader

  - by numerical25

  I am having issues passing values to my shader. My application compiles fine, but my cube object won't shade. Below is majority of my code. Most of my code for communicating with my shader is in createObject method myGame.cpp #include "MyGame.h" #include "OneColorCube.h" /* This code sets a projection and shows a turning cube. What has been added is the project, rotation and a rasterizer to change the rasterization of the cube. The issue that was going on was something with the effect file which was causing the vertices not to be rendered correctly.*/ typedef struct { ID3D10Effect* pEffect; ID3D10EffectTechnique* pTechnique; //vertex information ID3D10Buffer* pVertexBuffer; ID3D10Buffer* pIndicesBuffer; ID3D10InputLayout* pVertexLayout; UINT numVertices; UINT numIndices; }ModelObject; ModelObject modelObject; // World Matrix D3DXMATRIX WorldMatrix; // View Matrix D3DXMATRIX ViewMatrix; // Projection Matrix D3DXMATRIX ProjectionMatrix; ID3D10EffectMatrixVariable* pProjectionMatrixVariable = NULL; ID3D10EffectVectorVariable* pLightVarible = NULL; bool MyGame::InitDirect3D() { if(!DX3dApp::InitDirect3D()) { return false; } D3D10_RASTERIZER_DESC rastDesc; rastDesc.FillMode = D3D10_FILL_WIREFRAME; rastDesc.CullMode = D3D10_CULL_FRONT; rastDesc.FrontCounterClockwise = true; rastDesc.DepthBias = false; rastDesc.DepthBiasClamp = 0; rastDesc.SlopeScaledDepthBias = 0; rastDesc.DepthClipEnable = false; rastDesc.ScissorEnable = false; rastDesc.MultisampleEnable = false; rastDesc.AntialiasedLineEnable = false; ID3D10RasterizerState *g_pRasterizerState; mpD3DDevice->CreateRasterizerState(&rastDesc, &g_pRasterizerState); //mpD3DDevice->RSSetState(g_pRasterizerState); // Set up the World Matrix D3DXMatrixIdentity(&WorldMatrix); D3DXMatrixLookAtLH(&ViewMatrix, new D3DXVECTOR3(0.0f, 10.0f, -20.0f), new D3DXVECTOR3(0.0f, 0.0f, 0.0f), new D3DXVECTOR3(0.0f, 1.0f, 0.0f)); // Set up the projection matrix D3DXMatrixPerspectiveFovLH(&ProjectionMatrix, (float)D3DX_PI * 0.5f, (float)mWidth/(float)mHeight, 0.1f, 100.0f); if(!CreateObject()) { return false; } return true; } //These are actions that take place after the clearing of the buffer and before the present void MyGame::GameDraw() { static float rotationAngleY = 15.0f; static float rotationAngleX = 0.0f; static D3DXMATRIX rotationXMatrix; static D3DXMATRIX rotationYMatrix; // create the rotation matrix using the rotation angle D3DXMatrixRotationY(&rotationYMatrix, rotationAngleY); D3DXMatrixRotationX(&rotationXMatrix, rotationAngleX); //rotationAngleY += (float)D3DX_PI * 0.002f; //rotationAngleX += (float)D3DX_PI * 0.001f; WorldMatrix = rotationYMatrix * rotationXMatrix; // Set the input layout mpD3DDevice->IASetInputLayout(modelObject.pVertexLayout); // Set vertex buffer UINT stride = sizeof(VertexPos); UINT offset = 0; mpD3DDevice->IASetVertexBuffers(0, 1, &modelObject.pVertexBuffer, &stride, &offset); // Set primitive topology mpD3DDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST); //ViewMatrix._43 += 0.005f; // Combine and send the final matrix to the shader D3DXMATRIX finalMatrix = (WorldMatrix * ViewMatrix * ProjectionMatrix); pProjectionMatrixVariable->SetMatrix((float*)&finalMatrix); // make sure modelObject is valid // Render a model object D3D10_TECHNIQUE_DESC techniqueDescription; modelObject.pTechnique->GetDesc(&techniqueDescription); // Loop through the technique passes for(UINT p=0; p < techniqueDescription.Passes; ++p) { modelObject.pTechnique->GetPassByIndex(p)->Apply(0); // draw the cube using all 36 vertices and 12 triangles mpD3DDevice->Draw(36,0); } } //Render actually incapsulates Gamedraw, so you can call data before you actually clear the buffer or after you //present data void MyGame::Render() { DX3dApp::Render(); } bool MyGame::CreateObject() { //Create Layout D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"NORMAL",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 24, D3D10_INPUT_PER_VERTEX_DATA, 0} }; UINT numElements = (sizeof(layout)/sizeof(layout[0])); modelObject.numVertices = sizeof(vertices)/sizeof(VertexPos); for(int i = 0; i < modelObject.numVertices; i += 3) { D3DXVECTOR3 out; D3DXVECTOR3 v1 = vertices[0 + i].pos; D3DXVECTOR3 v2 = vertices[1 + i].pos; D3DXVECTOR3 v3 = vertices[2 + i].pos; D3DXVECTOR3 u = v2 - v1; D3DXVECTOR3 v = v3 - v1; D3DXVec3Cross(&out, &u, &v); D3DXVec3Normalize(&out, &out); vertices[0 + i].normal = out; vertices[1 + i].normal = out; vertices[2 + i].normal = out; } //Create buffer desc D3D10_BUFFER_DESC bufferDesc; bufferDesc.Usage = D3D10_USAGE_DEFAULT; bufferDesc.ByteWidth = sizeof(VertexPos) * modelObject.numVertices; bufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER; bufferDesc.CPUAccessFlags = 0; bufferDesc.MiscFlags = 0; D3D10_SUBRESOURCE_DATA initData; initData.pSysMem = vertices; //Create the buffer HRESULT hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pVertexBuffer); if(FAILED(hr)) return false; /* //Create indices DWORD indices[] = { 0,1,3, 1,2,3 }; ModelObject.numIndices = sizeof(indices)/sizeof(DWORD); bufferDesc.ByteWidth = sizeof(DWORD) * ModelObject.numIndices; bufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER; initData.pSysMem = indices; hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &ModelObject.pIndicesBuffer); if(FAILED(hr)) return false;*/ ///////////////////////////////////////////////////////////////////////////// //Set up fx files LPCWSTR effectFilename = L"effect.fx"; modelObject.pEffect = NULL; hr = D3DX10CreateEffectFromFile(effectFilename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, mpD3DDevice, NULL, NULL, &modelObject.pEffect, NULL, NULL); if(FAILED(hr)) return false; pProjectionMatrixVariable = modelObject.pEffect->GetVariableByName("Projection")->AsMatrix(); pLightVarible = modelObject.pEffect->GetVariableByName("lightSource")->AsVector(); //Dont sweat the technique. Get it! LPCSTR effectTechniqueName = "Render"; D3DXVECTOR3 vLight(10.0f, 10.0f, 10.0f); pLightVarible->SetFloatVector(vLight); modelObject.pTechnique = modelObject.pEffect->GetTechniqueByName(effectTechniqueName); if(modelObject.pTechnique == NULL) return false; //Create Vertex layout D3D10_PASS_DESC passDesc; modelObject.pTechnique->GetPassByIndex(0)->GetDesc(&passDesc); hr = mpD3DDevice->CreateInputLayout(layout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, &modelObject.pVertexLayout); if(FAILED(hr)) return false; return true; } And below is my shader effect.fx matrix Projection; float3 lightSource; float4 lightColor = {0.5, 0.5, 0.5, 0.5}; // PS_INPUT - input variables to the pixel shader // This struct is created and fill in by the // vertex shader struct PS_INPUT { float4 Pos : SV_POSITION; float4 Color : COLOR0; float4 Normal : NORMAL; }; //////////////////////////////////////////////// // Vertex Shader - Main Function /////////////////////////////////////////////// PS_INPUT VS(float4 Pos : POSITION, float4 Color : COLOR, float4 Normal : NORMAL) { PS_INPUT psInput; // Pass through both the position and the color psInput.Pos = mul( Pos, Projection ); psInput.Color = Color; psInput.Normal = Normal; return psInput; } /////////////////////////////////////////////// // Pixel Shader /////////////////////////////////////////////// float4 PS(PS_INPUT psInput) : SV_Target { float4 finalColor = 0; finalColor = saturate(dot(lightSource, psInput.Normal) * lightColor); return finalColor; } // Define the technique technique10 Render { pass P0 { SetVertexShader( CompileShader( vs_4_0, VS() ) ); SetGeometryShader( NULL ); SetPixelShader( CompileShader( ps_4_0, PS() ) ); } }

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• What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

  - by Alex Dunlop

  Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

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• Optimizing a lot of Scanner.findWithinHorizon(pattern, 0) calls

  - by darvids0n

  I'm building a process which extracts data from 6 csv-style files and two poorly laid out .txt reports and builds output CSVs, and I'm fully aware that there's going to be some overhead searching through all that whitespace thousands of times, but I never anticipated converting about about 50,000 records would take 12 hours. Excerpt of my manual matching code (I know it's horrible that I use lists of tokens like that, but it was the best thing I could think of): public static String lookup(List<String> tokensBefore, List<String> tokensAfter) { String result = null; while(_match(tokensBefore)) { // block until all input is read if(id.hasNext()) { result = id.next(); // capture the next token that matches if(_matchImmediate(tokensAfter)) // try to match tokensAfter to this result return result; } else return null; // end of file; no match } return null; // no matches } private static boolean _match(List<String> tokens) { return _match(tokens, true); } private static boolean _match(List<String> tokens, boolean block) { if(tokens != null && !tokens.isEmpty()) { if(id.findWithinHorizon(tokens.get(0), 0) == null) return false; for(int i = 1; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(id.hasNext() && !id.next().matches(tokens.get(i))) { break; // break to blocking behaviour } } } else { return true; // empty list always matches } if(block) return _match(tokens); // loop until we find something or nothing else return false; // return after just one attempted match } private static boolean _matchImmediate(List<String> tokens) { if(tokens != null) { for(int i = 0; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(!id.hasNext() || !id.next().matches(tokens.get(i))) { return false; // doesn't match, or end of file } } return false; // we have some serious problems if this ever gets called } else { return true; // empty list always matches } } Basically wondering how I would work in an efficient string search (Boyer-Moore or similar). My Scanner id is scanning a java.util.String, figured buffering it to memory would reduce I/O since the search here is being performed thousands of times on a relatively small file. The performance increase compared to scanning a BufferedReader(FileReader(File)) was probably less than 1%, the process still looks to be taking a LONG time. I've also traced execution and the slowness of my overall conversion process is definitely between the first and last like of the lookup method. In fact, so much so that I ran a shortcut process to count the number of occurrences of various identifiers in the .csv-style files (I use 2 lookup methods, this is just one of them) and the process completed indexing approx 4 different identifiers for 50,000 records in less than a minute. Compared to 12 hours, that's instant. Some notes (updated): I don't necessarily need the pattern-matching behaviour, I only get the first field of a line of text so I need to match line breaks or use Scanner.nextLine(). All ID numbers I need start at position 0 of a line and run through til the first block of whitespace, after which is the name of the corresponding object. I would ideally want to return a String, not an int locating the line number or start position of the result, but if it's faster then it will still work just fine. If an int is being returned, however, then I would now have to seek to that line again just to get the ID; storing the ID of every line that is searched sounds like a way around that. Anything to help me out, even if it saves 1ms per search, will help, so all input is appreciated. Thankyou! Usage scenario 1: I have a list of objects in file A, who in the old-style system have an id number which is not in file A. It is, however, POSSIBLY in another csv-style file (file B) or possibly still in a .txt report (file C) which each also contain a bunch of other information which is not useful here, and so file B needs to be searched through for the object's full name (1 token since it would reside within the second column of any given line), and then the first column should be the ID number. If that doesn't work, we then have to split the search token by whitespace into separate tokens before doing a search of file C for those tokens as well. Generalised code: String field; for (/* each record in file A */) { /* construct the rest of this object from file A info */ // now to find the ID, if we can List<String> objectName = new ArrayList<String>(1); objectName.add(Pattern.quote(thisObject.fullName)); field = lookup(objectSearchToken, objectName); // search file B if(field == null) // not found in file B { lookupReset(false); // initialise scanner to check file C objectName.clear(); // not using the full name String[] tokens = thisObject.fullName.split(id.delimiter().pattern()); for(String s : tokens) objectName.add(Pattern.quote(s)); field = lookup(objectSearchToken, objectName); // search file C lookupReset(true); // back to file B } else { /* found it, file B specific processing here */ } if(field != null) // found it in B or C thisObject.ID = field; } The objectName tokens are all uppercase words with possible hyphens or apostrophes in them, separated by spaces. Much like a person's name. As per a comment, I will pre-compile the regex for my objectSearchToken, which is just [\r\n]+. What's ending up happening in file C is, every single line is being checked, even the 95% of lines which don't contain an ID number and object name at the start. Would it be quicker to use ^[\r\n]+.*(objectname) instead of two separate regexes? It may reduce the number of _match executions. The more general case of that would be, concatenate all tokensBefore with all tokensAfter, and put a .* in the middle. It would need to be matching backwards through the file though, otherwise it would match the correct line but with a huge .* block in the middle with lots of lines. The above situation could be resolved if I could get java.util.Scanner to return the token previous to the current one after a call to findWithinHorizon. I have another usage scenario. Will put it up asap.

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• How to implement Google Maps new version of API v2

  - by bapatla

  Hi every one I came to know that google maps has deprecated its previous version API v1 and introduced a new version of google maps API v2. I tried out one example by following some links in google any how i am pretty sure that i got the api key correctly by providing the exact hash key code and managed to get the correct api key. Now i managed to write some code as well but when i tried to execute the code i am getting the errors please help me to solve this here is my code and i even tried the sample codes provided by google play services an i got the same problem this is the sample that i have done by referring some links in google main activity package com.example.apv; import com.google.android.gms.maps.CameraUpdateFactory; import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.MapFragment; import com.google.android.gms.maps.model.BitmapDescriptorFactory; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.MarkerOptions; import android.os.Bundle; import android.app.Activity; import android.app.FragmentManager; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); FragmentManager fragmentManager = getFragmentManager(); MapFragment mapFragment = (MapFragment) fragmentManager.findFragmentById(R.id.map); GoogleMap googleMap = mapFragment.getMap(); LatLng sfLatLng = new LatLng(37.7750, -122.4183); googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); googleMap.addMarker(new MarkerOptions() .position(sfLatLng) .title("San Francisco") .snippet("Population: 776733") .icon(BitmapDescriptorFactory.defaultMarker( BitmapDescriptorFactory.HUE_AZURE))); googleMap.getUiSettings().setCompassEnabled(true); googleMap.getUiSettings().setZoomControlsEnabled(true); googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(sfLatLng, 10)); } } main.xml <?xml version="1.0" encoding="utf-8"?> <fragment xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/map" android:layout_width="match_parent" android:layout_height="match_parent" class="com.google.android.gms.maps.MapFragment"/> and finally my manifest file <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.apv" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17"/> <permission android:name="com.codebybrian.mapsample.permission.MAPS_RECEIVE" android:protectionLevel="signature"/> <!--Required permissions--> permission oid:name="com.codebybrian.mapsample.permission.MAPS_RECEIVE"/> <!--Used by the API to download map tiles from Google Maps servers: --> <uses-permission android:name="android.permission.INTERNET"/> <!--Allows the API to access Google web-based services: --> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <!--Optional permissions--> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> <!--Version 2 of the Google Maps Android API requires OpenGL ES version 2 --> <uses-feature android:glEsVersion="0x00020000" android:required="true"/> application android:label="@string/app_name" android:icon="@drawable/ic_launcher"> <activity android:name=".MyMapActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="AZzaSSsBmhi4dXoKSylGGmjkQ5Jev9UdAJBjk"/> </application> </manifest> i run my application in emulator of version 4.2 and api level of 17 i got following error 12-17 10:06:52.590: E/Trace(826): error opening trace file: No such file or directory (2) 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.590: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.680: I/ActivityThread(826): Pub com.google.android.gms.plus;com.google.android.gms.plus.action: com.google.android.gms.plus.provider.PlusProvider 12-17 10:06:52.740: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.740: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 12-17 10:06:52.760: W/Trace(826): Unexpected value from nativeGetEnabledTags: 0 later i came to know that these version cant execute in emulator so i tried executing it with two devices one is Sony xperia u of android version 2.3.7 and Samsung galaxy tab of android version 4.1.1 and these are my outputs 12-17 14:37:02.468: D/AndroidRuntime(7636): Shutting down VM 12-17 14:37:02.468: W/dalvikvm(7636): threadid=1: thread exiting with uncaught exception (group=0x41f672a0) 12-17 14:37:02.476: E/AndroidRuntime(7636): FATAL EXCEPTION: main 12-17 14:37:02.476: E/AndroidRuntime(7636): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.apv/com.example.apv.MyMapActivity}: java.lang.ClassNotFoundException: com.example.apv.MyMapActivity 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2021) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.access$600(ActivityThread.java:140) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.os.Handler.dispatchMessage(Handler.java:99) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.os.Looper.loop(Looper.java:137) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.main(ActivityThread.java:4895) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.reflect.Method.invokeNative(Native Method) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.reflect.Method.invoke(Method.java:511) 12-17 14:37:02.476: E/AndroidRuntime(7636): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller .run(ZygoteInit.java:994) 12-17 14:37:02.476: E/AndroidRuntime(7636): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761) 12-17 14:37:02.476: E/AndroidRuntime(7636): at dalvik.system.NativeStart.main(Native Method) 12-17 14:37:02.476: E/AndroidRuntime(7636): Caused by: java.lang.ClassNotFoundException: com.example.apv.MyMapActivity 12-17 14:37:02.476: E/AndroidRuntime(7636): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.ClassLoader.loadClass(ClassLoader.java:501) 12-17 14:37:02.476: E/AndroidRuntime(7636): at java.lang.ClassLoader.loadClass(ClassLoader.java:461) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.Instrumentation.newActivity(Instrumentation.java:1068) 12-17 14:37:02.476: E/AndroidRuntime(7636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2012) 12-17 14:37:02.476: E/AndroidRuntime(7636): ... 11 more could any one please suggest me to how to get this done and give me some links of new version API v2 tutorials of google maps and some examples links please help me

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• Android Uncaught Exception

  - by Agrim Asthana

  09-30 02:32:31.474: D/ddm-heap(214): Got feature list request 09-30 02:32:31.634: D/AndroidRuntime(214): Shutting down VM 09-30 02:32:31.634: W/dalvikvm(214): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 09-30 02:32:31.634: E/AndroidRuntime(214): Uncaught handler: thread main exiting due to uncaught exception 09-30 02:32:31.654: E/AndroidRuntime(214): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.mjcet.mjcet/com.mjcet.mjcet.MJCET}: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Handler.dispatchMessage(Handler.java:99) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Looper.loop(Looper.java:123) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.main(ActivityThread.java:4363) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invokeNative(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invoke(Method.java:521) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.NativeStart.main(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): Caused by: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:573) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:532) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409) 09-30 02:32:31.654: E/AndroidRuntime(214): ... 11 more 09-30 02:32:31.684: I/dalvikvm(214): threadid=7: reacting to signal 3 09-30 02:32:31.684: E/dalvikvm(214): Unable to open stack trace file '/data/anr/traces.txt': Permission denied the above is my debugging output for the below activities LOGINACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; //import android.widget.TextView; import android.widget.Button; import android.widget.EditText; import android.view.View.OnClickListener; public class LoginActivity extends Activity { EditText txtUserName; EditText txtPassword; Button btnLogin; Button btnCancel; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // setting default screen to login.xml setContentView(R.layout.main); txtUserName=(EditText)this.findViewById(R.id.txtUname); txtPassword=(EditText)this.findViewById(R.id.txtPwd); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin.setOnClickListener(new OnClickListener() { public void onClick(View v) { // Switching to Register screen if((txtUserName.getText().toString()).equals(txtPassword.getText().toString())) { Intent myIntent = new Intent(getApplicationContext(),SampleActivity.class); startActivityForResult(myIntent, 0); } } } ); } } SAMPLE ACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class SampleActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set View to register.xml setContentView(R.layout.lol); TextView HomeScreen = (TextView) findViewById(R.id.back); HomeScreen.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // Closing registration screen // Switching to Login Screen/closing register screen finish(); } }); } } and here are my 2 layouts MAIN.XML <TableLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#000000" android:stretchColumns="1"> <TableRow> <TextView android:text="@string/user_name" android:textColor="#347235" android:id="@+id/TextView01" android:layout_width="wrap_content" android:layout_marginLeft="25dip" android:layout_height="wrap_content"> </TextView> <EditText android:text="" android:inputType="text" android:id="@+id/txtUname" android:layout_weight="0.75" android:layout_width="wrap_content" android:layout_marginRight="10dip" android:layout_marginBottom="5dip" android:background="#FFFFFF" android:layout_height="wrap_content"> </EditText> </TableRow> <TableRow> <TextView android:text="@string/password" android:textColor="#347235" android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="25dip"> </TextView> <EditText android:text="" android:inputType="textPassword" android:id="@+id/txtPwd" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginRight="10dip" android:layout_weight="1" android:background="#FFFFFF" android:gravity="center"> </EditText> </TableRow> <TableRow> <Button android:id="@+id/btnLogin" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="50dip" android:onClick="onClickMyButton" android:text="@string/login" /> <Button android:id="@+id/btnCancel" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="100dip" android:layout_marginRight="50dip" android:text="@string/cancel" /> </TableRow> <FrameLayout android:layout_width="wrap_content" android:layout_height="match_parent" > <ImageView android:layout_width="fill_parent" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/logo_invert" android:contentDescription="@drawable/logo_invert"/> </FrameLayout> </TableLayout> and finally LOL.xml <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:background="#000000" android:layout_height="fill_parent" > <ImageView android:layout_width="fill_parent" android:id="@+id/back" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/lol" android:contentDescription="@drawable/lol"> </ImageView> <RelativeLayout android:layout_width="match_parent" android:layout_height="138dp" android:orientation="vertical" android:gravity="bottom" > <TextView android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:text="@string/coming_soon" android:textColor="#347235" /> </RelativeLayout> </FrameLayout> I get a force close upon initialization.. and yes this is my first android app :)

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• SocketChannel in Java sends data, but it doesn't get to destination application

  - by Peterson

  Hi Everybody, I'm suffering a lot to create a simple ChatServer in Java, using the NIO libraries. Wonder if someone could help me. I am doing that by using SocketChannel and Selector to handle multiple clients in a single thread. The problem is: I am able to accept new connections and get it's data, but when I try to send data back, the SocketChannel simply doesn't work. In the method write(), it returns a integer that is the same size of the data i'm passing to it, but the client never receives that data. Strangely, when I close the server application, the client receives the data. It's like the socketchannel maintains a buffer, and it only get flushed when I close the application. Here are some more details, to give you more information to help. I'm handling the events in this piece of code: private void run() throws IOException { ServerSocketChannel ssc = ServerSocketChannel.open(); // Set it to non-blocking, so we can use select ssc.configureBlocking( false ); // Get the Socket connected to this channel, and bind it // to the listening port this.serverSocket = ssc.socket(); InetSocketAddress isa = new InetSocketAddress( this.port ); serverSocket.bind( isa ); // Create a new Selector for selecting this.masterSelector = Selector.open(); // Register the ServerSocketChannel, so we can // listen for incoming connections ssc.register( masterSelector, SelectionKey.OP_ACCEPT ); while (true) { // See if we've had any activity -- either // an incoming connection, or incoming data on an // existing connection int num = masterSelector.select(); // If we don't have any activity, loop around and wait // again if (num == 0) { continue; } // Get the keys corresponding to the activity // that has been detected, and process them // one by one Set keys = masterSelector.selectedKeys(); Iterator it = keys.iterator(); while (it.hasNext()) { // Get a key representing one of bits of I/O // activity SelectionKey key = (SelectionKey)it.next(); // What kind of activity is it? if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Aceita a conexão Socket s = serverSocket.accept(); System.out.println( "LOG: Conexao TCP aceita de " + s.getInetAddress() + ":" + s.getPort() ); // Make sure to make it non-blocking, so we can // use a selector on it. SocketChannel sc = s.getChannel(); sc.configureBlocking( false ); // Registra a conexao no seletor, apenas para leitura sc.register( masterSelector, SelectionKey.OP_READ ); } else if ( key.isReadable() ) { SocketChannel sc = null; // It's incoming data on a connection, so // process it sc = (SocketChannel)key.channel(); // Verifica se a conexão corresponde a um cliente já existente if((clientsMap.getClient(key)) != null){ boolean closedConnection = !processIncomingClientData(key); if(closedConnection){ int id = clientsMap.getClient(key); closeClient(id); } } else { boolean clientAccepted = processIncomingDataFromNewClient(key); if(!clientAccepted){ // Se o cliente não foi aceito, sua conexão é simplesmente fechada sc.socket().close(); sc.close(); key.cancel(); } } } } // We remove the selected keys, because we've dealt // with them. keys.clear(); } } This piece of code is simply handles new clients that wants to connect to the chat. So, a client makes a TCP connection to the server, and once it gets accepted, it sends data to the server following a simply text protocol, informing his id and asking to get registrated to the server. I handle this in the method processIncomingDataFromNewClient(key). I'm also keeping a map of clients and its connections in a data structure similar to a hashtable. I? doing that because I need to recover a client Id from a connection and a connection from a client Id. This is can be shown in: clientsMap.getClient(key). But the problem itself resides in the method processIncomingDataFromNewClient(key). There, I simply read the data that the client sent to me, validate it, and if it's ok, I send a message back to the client to tell that it is connected to the chat server. Here is a similar piece of code: private boolean processIncomingDataFromNewClient(SelectionKey key){ SocketChannel sc = (SocketChannel) key.channel(); String connectionOrigin = sc.socket().getInetAddress() + ":" + sc.socket().getPort(); int id = 0; //id of the client buf.clear(); int bytesRead = 0; try { bytesRead = sc.read(buf); if(bytesRead<=0){ System.out.println("Conexão fechada pelo: " + connectionOrigin); return false; } System.out.println("LOG: " + bytesRead + " bytes lidos de " + connectionOrigin); String msg = new String(buf.array(),0,bytesRead); // Do validations with the client sent me here // gets the client id }catch (Exception e) { e.printStackTrace(); System.out.println("LOG: Oops. Cliente não conhece o protocolo. Fechando a conexão: " + connectionOrigin); System.out.println("LOG: Primeiros 10 caracteres enviados pelo cliente: " + msg); return false; } } } catch (IOException e) { System.out.println("LOG: Erro ao ler dados da conexao: " + connectionOrigin); System.out.println("LOG: "+ e.getLocalizedMessage()); System.out.println("LOG: Fechando a conexão..."); return false; } // If it gets to here, the protocol is ok and we can add the client boolean inserted = clientsMap.addClient(key, id); if(!inserted){ System.out.println("LOG: Não foi possível adicionar o cliente. Ou ele já está conectado ou já têm clientes demais. Id: " + id); System.out.println("LOG: Fechando a conexão: " + connectionOrigin); return false; } System.out.println("LOG: Novo cliente conectado! Enviando mesnsagem de confirmação. Id: " + id + " Conexao: " + connectionOrigin); /* Here is the error */ sendMessage(id, "Servidor pet: connection accepted"); System.out.println("LOG: Novo cliente conectado! Id: " + id + " Conexao: " + connectionOrigin); return true; } And finally, the method sendMessage(SelectionKey key) looks like this: private void sendMessage(int destId, String msg) { Charset charset = Charset.forName("ISO-8859-1"); CharBuffer charBuffer = CharBuffer.wrap(msg, 0, msg.length()); ByteBuffer bf = charset.encode(charBuffer); //bf.flip(); int bytesSent = 0; SelectionKey key = clientsMap.getClient(destId); SocketChannel sc = (SocketChannel) key.channel(); try { / int total_bytes_sent = 0; while(total_bytes_sent < msg.length()){ bytesSent = sc.write(bf); total_bytes_sent += bytesSent; } System.out.println("LOG: Bytes enviados para o cliente " + destId + ": "+ total_bytes_sent + " Tamanho da mensagem: " + msg.length()); } catch (IOException e) { System.out.println("LOG: Erro ao mandar mensagem para: " + destId); System.out.println("LOG: " + e.getLocalizedMessage()); } } So, what is happening is that the server, when send a message, prints something like this: LOG: Bytes sent to the client: 28 Size of the message: 28 So, it tells that it sent the data, but the chat client keeps blocking, waiting in the recv() method. So, the data never gets to it. When I close the server application, though, all the data appears in the client. I wonder why. It is important to say that the client is in C and the server JAVA, and I'm running both in the same machine, an Ubuntu Guest in virtualbox under windows. I also run both under windows host and under linuxes hosts, and keep getting the same strange problem. I'm sorry for the great lenght of this question, but I already searched a lot of places for an answer, found a lot of tutorials and questions, including here at StackOverflow, but coundn't find a reasonable explanation. I am really not liking this Java NIO, and i saw a lot of people complaining about it too. I am thinking that if I had done that in C it would have been a lot easier :-D So, if someone could help me and even discuss this behavor, it would be great! :-) Thanks everybody in advance, Péterson

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• Questions related to writing your own file downloader using multiple threads java

  - by Shekhar

  Hello In my current company, i am doing a PoC on how we can write a file downloader utility. We have to use socket programming(TCP/IP) for downloading the files. One of the requirements of the client is that a file(which will be large in size) should be transfered in chunks for example if we have a file of 5Mb size then we can have 5 threads which transfer 1 Mb each. I have written a small application which downloads a file. You can download the eclipe project from http://www.fileflyer.com/view/QM1JSC0 A brief explanation of my classes FileSender.java This class provides the bytes of file. It has a method called sendBytesOfFile(long start,long end, long sequenceNo) which gives the number of bytes. import java.io.File; import java.io.IOException; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileSender { private static final String FILE_NAME = "C:\\shared\\test.pdf"; public ByteArrayWrapper sendBytesOfFile(long start,long end, long sequenceNo){ try { File file = new File(FILE_NAME); byte[] fileBytes = FileUtils.readFileToByteArray(file); System.out.println("Size of file is " +fileBytes.length); System.out.println(); System.out.println("Start "+start +" end "+end); byte[] bytes = getByteArray(fileBytes, start, end); ByteArrayWrapper wrapper = new ByteArrayWrapper(bytes, sequenceNo); return wrapper; } catch (IOException e) { throw new RuntimeException(e); } } private byte[] getByteArray(byte[] bytes, long start, long end){ long arrayLength = end-start; System.out.println("Start : "+start +" end : "+end + " Arraylength : "+arrayLength +" length of source array : "+bytes.length); byte[] arr = new byte[(int)arrayLength]; for(int i = (int)start, j =0; i < end;i++,j++){ arr[j] = bytes[i]; } return arr; } public static long fileSize(){ File file = new File(FILE_NAME); return file.length(); } } Second Class is FileReceiver.java - This class receives the file. Small Explanation what this file does This class finds the size of the file to be fetched from Sender Depending upon the size of the file it finds the start and end position till the bytes needs to be read. It starts n number of threads giving each thread start,end, sequence number and a list which all the threads share. Each thread reads the number of bytes and creates a ByteArrayWrapper. ByteArrayWrapper objects are added to the list Then i have while loop which basically make sure that all threads have done their work finally it sorts the list based on the sequence number. then the bytes are joined, and a complete byte array is formed which is converted to a file. Code of File Receiver package com.filedownloader; import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; import java.util.zip.CRC32; import org.apache.commons.io.FileUtils; public class FileReceiver { public static void main(String[] args) { FileReceiver receiver = new FileReceiver(); receiver.receiveFile(); } public void receiveFile(){ long startTime = System.currentTimeMillis(); long numberOfThreads = 10; long filesize = FileSender.fileSize(); System.out.println("File size received "+filesize); long start = filesize/numberOfThreads; List<ByteArrayWrapper> list = new ArrayList<ByteArrayWrapper>(); for(long threadCount =0; threadCount<numberOfThreads ;threadCount++){ FileDownloaderTask task = new FileDownloaderTask(threadCount*start,(threadCount+1)*start,threadCount,list); new Thread(task).start(); } while(list.size() != numberOfThreads){ // this is done so that all the threads should complete their work before processing further. //System.out.println("Waiting for threads to complete. List size "+list.size()); } if(list.size() == numberOfThreads){ System.out.println("All bytes received "+list); Collections.sort(list, new Comparator<ByteArrayWrapper>() { @Override public int compare(ByteArrayWrapper o1, ByteArrayWrapper o2) { long sequence1 = o1.getSequence(); long sequence2 = o2.getSequence(); if(sequence1 < sequence2){ return -1; }else if(sequence1 > sequence2){ return 1; } else{ return 0; } } }); byte[] totalBytes = list.get(0).getBytes(); byte[] firstArr = null; byte[] secondArr = null; for(int i = 1;i<list.size();i++){ firstArr = totalBytes; secondArr = list.get(i).getBytes(); totalBytes = concat(firstArr, secondArr); } System.out.println(totalBytes.length); convertToFile(totalBytes,"c:\\tmp\\test.pdf"); long endTime = System.currentTimeMillis(); System.out.println("Total time taken with "+numberOfThreads +" threads is "+(endTime-startTime)+" ms" ); } } private byte[] concat(byte[] A, byte[] B) { byte[] C= new byte[A.length+B.length]; System.arraycopy(A, 0, C, 0, A.length); System.arraycopy(B, 0, C, A.length, B.length); return C; } private void convertToFile(byte[] totalBytes,String name) { try { FileUtils.writeByteArrayToFile(new File(name), totalBytes); } catch (IOException e) { throw new RuntimeException(e); } } } Code of ByteArrayWrapper package com.filedownloader; import java.io.Serializable; public class ByteArrayWrapper implements Serializable{ private static final long serialVersionUID = 3499562855188457886L; private byte[] bytes; private long sequence; public ByteArrayWrapper(byte[] bytes, long sequenceNo) { this.bytes = bytes; this.sequence = sequenceNo; } public byte[] getBytes() { return bytes; } public long getSequence() { return sequence; } } Code of FileDownloaderTask import java.util.List; public class FileDownloaderTask implements Runnable { private List<ByteArrayWrapper> list; private long start; private long end; private long sequenceNo; public FileDownloaderTask(long start,long end,long sequenceNo,List<ByteArrayWrapper> list) { this.list = list; this.start = start; this.end = end; this.sequenceNo = sequenceNo; } @Override public void run() { ByteArrayWrapper wrapper = new FileSender().sendBytesOfFile(start, end, sequenceNo); list.add(wrapper); } } Questions related to this code 1) Does file downloading becomes fast when multiple threads is used? In this code i am not able to see the benefit. 2) How should i decide how many threads should i create ? 3) Are their any opensource libraries which does that 4) The file which file receiver receives is valid and not corrupted but checksum (i used FileUtils of common-io) does not match. Whats the problem? 5) This code gives out of memory when used with large file(above 100 Mb) i.e. because byte array which is created. How can i avoid? I know this is a very bad code but i have to write this in one day -:). Please suggest any other good way to do this? Thanks Shekhar

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• How do I get .NET to garbage collect aggressively?

  - by mmr

  I have an application that is used in image processing, and I find myself typically allocating arrays in the 4000x4000 ushort size, as well as the occasional float and the like. Currently, the .NET framework tends to crash in this app apparently randomly, almost always with an out of memory error. 32mb is not a huge declaration, but if .NET is fragmenting memory, then it's very possible that such large continuous allocations aren't behaving as expected. Is there a way to tell the garbage collector to be more aggressive, or to defrag memory (if that's the problem)? I realize that there's the GC.Collect and GC.WaitForPendingFinalizers calls, and I've sprinkled them pretty liberally through my code, but I'm still getting the errors. It may be because I'm calling dll routines that use native code a lot, but I'm not sure. I've gone over that C++ code, and make sure that any memory I declare I delete, but still I get these C# crashes, so I'm pretty sure it's not there. I wonder if the C++ calls could be interfering with the GC, making it leave behind memory because it once interacted with a native call-- is that possible? If so, can I turn that functionality off? EDIT: Here is some very specific code that will cause the crash. According to this SO question, I do not need to be disposing of the BitmapSource objects here. Here is the naive version, no GC.Collects in it. It generally crashes on iteration 4 to 10 of the undo procedure. This code replaces the constructor in a blank WPF project, since I'm using WPF. I do the wackiness with the bitmapsource because of the limitations I explained in my answer to @dthorpe below as well as the requirements listed in this SO question. public partial class Window1 : Window { public Window1() { InitializeComponent(); //Attempts to create an OOM crash //to do so, mimic minute croppings of an 'image' (ushort array), and then undoing the crops int theRows = 4000, currRows; int theColumns = 4000, currCols; int theMaxChange = 30; int i; List<ushort[]> theList = new List<ushort[]>();//the list of images in the undo/redo stack byte[] displayBuffer = null;//the buffer used as a bitmap source BitmapSource theSource = null; for (i = 0; i < theMaxChange; i++) { currRows = theRows - i; currCols = theColumns - i; theList.Add(new ushort[(theRows - i) * (theColumns - i)]); displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create(currCols, currRows, 96, 96, PixelFormats.Gray8, null, displayBuffer, (currCols * PixelFormats.Gray8.BitsPerPixel + 7) / 8); System.Console.WriteLine("Got to change " + i.ToString()); System.Threading.Thread.Sleep(100); } //should get here. If not, then theMaxChange is too large. //Now, go back up the undo stack. for (i = theMaxChange - 1; i >= 0; i--) { displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create((theColumns - i), (theRows - i), 96, 96, PixelFormats.Gray8, null, displayBuffer, ((theColumns - i) * PixelFormats.Gray8.BitsPerPixel + 7) / 8); System.Console.WriteLine("Got to undo change " + i.ToString()); System.Threading.Thread.Sleep(100); } } } Now, if I'm explicit in calling the garbage collector, I have to wrap the entire code in an outer loop to cause the OOM crash. For me, this tends to happen around x = 50 or so: public partial class Window1 : Window { public Window1() { InitializeComponent(); //Attempts to create an OOM crash //to do so, mimic minute croppings of an 'image' (ushort array), and then undoing the crops for (int x = 0; x < 1000; x++){ int theRows = 4000, currRows; int theColumns = 4000, currCols; int theMaxChange = 30; int i; List<ushort[]> theList = new List<ushort[]>();//the list of images in the undo/redo stack byte[] displayBuffer = null;//the buffer used as a bitmap source BitmapSource theSource = null; for (i = 0; i < theMaxChange; i++) { currRows = theRows - i; currCols = theColumns - i; theList.Add(new ushort[(theRows - i) * (theColumns - i)]); displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create(currCols, currRows, 96, 96, PixelFormats.Gray8, null, displayBuffer, (currCols * PixelFormats.Gray8.BitsPerPixel + 7) / 8); } //should get here. If not, then theMaxChange is too large. //Now, go back up the undo stack. for (i = theMaxChange - 1; i >= 0; i--) { displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create((theColumns - i), (theRows - i), 96, 96, PixelFormats.Gray8, null, displayBuffer, ((theColumns - i) * PixelFormats.Gray8.BitsPerPixel + 7) / 8); GC.WaitForPendingFinalizers();//force gc to collect, because we're in scenario 2, lots of large random changes GC.Collect(); } System.Console.WriteLine("Got to changelist " + x.ToString()); System.Threading.Thread.Sleep(100); } } } If I'm mishandling memory in either scenario, if there's something I should spot with a profiler, let me know. That's a pretty simple routine there. Unfortunately, it looks like @Kevin's answer is right-- this is a bug in .NET and how .NET handles objects larger than 85k. This situation strikes me as exceedingly strange; could Powerpoint be rewritten in .NET with this kind of limitation, or any of the other Office suite applications? 85k does not seem to me to be a whole lot of space, and I'd also think that any program that uses so-called 'large' allocations frequently would become unstable within a matter of days to weeks when using .NET. EDIT: It looks like Kevin is right, this is a limitation of .NET's GC. For those who don't want to follow the entire thread, .NET has four GC heaps: gen0, gen1, gen2, and LOH (Large Object Heap). Everything that's 85k or smaller goes on one of the first three heaps, depending on creation time (moved from gen0 to gen1 to gen2, etc). Objects larger than 85k get placed on the LOH. The LOH is never compacted, so eventually, allocations of the type I'm doing will eventually cause an OOM error as objects get scattered about that memory space. We've found that moving to .NET 4.0 does help the problem somewhat, delaying the exception, but not preventing it. To be honest, this feels a bit like the 640k barrier-- 85k ought to be enough for any user application (to paraphrase this video of a discussion of the GC in .NET). For the record, Java does not exhibit this behavior with its GC.

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• Implementing union of Set using basic java array

  - by lupindeterd

  Note: This is an assignment. Hi, Continuing with my Set implementation using Java basic array, I'm now struggling with the 3 to last function namely the union. import java.io.*; class Set { private int numberOfElements = 0; private String[] setElements = new String[5]; private int maxNumberOfElements = 5; // constructor for our Set class public Set(int numberOfE, int setE, int maxNumberOfE) { int numberOfElements = numberOfE; String[] setElements = new String[setE]; int maxNumberOfElements = maxNumberOfE; } // Helper method to shorten/remove element of array since we're using basic array instead of ArrayList or HashSet from collection interface :( static String[] removeAt(int k, String[] arr) { final int L = arr.length; String[] ret = new String[L - 1]; System.arraycopy(arr, 0, ret, 0, k); System.arraycopy(arr, k + 1, ret, k, L - k - 1); return ret; } int findElement(String element) { int retval = 0; for ( int i = 0; i < setElements.length; i++) { if ( setElements[i] != null && setElements[i].equals(element) ) { return retval = i; } retval = -1; } return retval; } void add(String newValue) { int elem = findElement(newValue); if( numberOfElements < maxNumberOfElements && elem == -1 ) { setElements[numberOfElements] = newValue; numberOfElements++; } } int getLength() { if ( setElements != null ) { return setElements.length; } else { return 0; } } String[] emptySet() { setElements = new String[0]; return setElements; } Boolean isFull() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == maxNumberOfElements ){ return True; } else { return False; } } Boolean isEmpty() { Boolean True = new Boolean(true); Boolean False = new Boolean(false); if ( setElements.length == 0 ) { return True; } else { return False; } } void remove(String newValue) { for ( int i = 0; i < setElements.length; i++) { if ( setElements[i].equals(newValue) ) { setElements = removeAt(i,setElements); } } } int isAMember(String element) { int retval = -1; for ( int i = 0; i < setElements.length; i++ ) { if (setElements[i] != null && setElements[i].equals(element)) { return retval = i; } } return retval; } void printSet() { for ( int i = 0; i < setElements.length; i++) { System.out.println("Member elements on index: "+ i +" " + setElements[i]); } } String[] getMember() { String[] tempArray = new String[setElements.length]; for ( int i = 0; i < setElements.length; i++) { if(setElements[i] != null) { tempArray[i] = setElements[i]; } } return tempArray; } Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } } // This is the SetDemo class that will make use of our Set class class SetDemo { public static void main(String[] args) { //get input from keyboard BufferedReader keyboard; InputStreamReader reader; String temp = ""; reader = new InputStreamReader(System.in); keyboard = new BufferedReader(reader); try { System.out.println("Enter string element to be added" ); temp = keyboard.readLine( ); System.out.println("You entered " + temp ); } catch (IOException IOerr) { System.out.println("There was an error during input"); } /* ************************************************************************** * Test cases for our new created Set class. * ************************************************************************** */ Set setA = new Set(1,10,10); setA.add(temp); setA.add("b"); setA.add("b"); setA.add("hello"); setA.add("world"); setA.add("six"); setA.add("seven"); setA.add("b"); int size = setA.getLength(); System.out.println("Set size is: " + size ); Boolean isempty = setA.isEmpty(); System.out.println("Set is empty? " + isempty ); int ismember = setA.isAMember("sixb"); System.out.println("Element six is member of setA? " + ismember ); Boolean output = setA.isFull(); System.out.println("Set is full? " + output ); setA.printSet(); int index = setA.findElement("world"); System.out.println("Element b located on index: " + index ); setA.remove("b"); setA.emptySet(); int resize = setA.getLength(); System.out.println("Set size is: " + resize ); setA.printSet(); Set setB = new Set(0,10,10); Set SetA = setA.union(setB,setA); } } Ok the method in question will be the implementation of union. As such this: Set union(Set x, Set y) { String[] newtemparray = new String[x.getLength]; newtemparray = x.getMember; return x; } I got this error: symbol : variable getLength location: class Set String[] newtemparray = new String[x.getLength]; ^ d:\javaprojects\Set.java:122: cannot find symbol symbol : variable getMember location: class Set newtemparray = x.getMember; ^ 2 errors My approach for union would be: *) create temporary array of string with size of the object x length. *) store object x members to temporary array by looping the object and calling the getMember *) loop object y members and check if element exist against temporary array. *) discard if it exist/add if it is not there *) return obj x with the union array. thanks, lupin

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• Marshalling to a native library in C#

  - by Daniel Baulig

  I'm having trouble calling functions of a native library from within managed C# code. I am developing for the 3.5 compact framework (Windows Mobile 6.x) just in case this would make any difference. I am working with the waveIn* functions from coredll.dll (these are in winmm.dll in regular Windows I believe). This is what I came up with: // namespace winmm; class winmm [StructLayout(LayoutKind.Sequential)] public struct WAVEFORMAT { public ushort wFormatTag; public ushort nChannels; public uint nSamplesPerSec; public uint nAvgBytesPerSec; public ushort nBlockAlign; public ushort wBitsPerSample; public ushort cbSize; } [StructLayout(LayoutKind.Sequential)] public struct WAVEHDR { public IntPtr lpData; public uint dwBufferLength; public uint dwBytesRecorded; public IntPtr dwUser; public uint dwFlags; public uint dwLoops; public IntPtr lpNext; public IntPtr reserved; } public delegate void AudioRecordingDelegate(IntPtr deviceHandle, uint message, IntPtr instance, ref WAVEHDR wavehdr, IntPtr reserved2); [DllImport("coredll.dll")] public static extern int waveInAddBuffer(IntPtr hWaveIn, ref WAVEHDR lpWaveHdr, uint cWaveHdrSize); [DllImport("coredll.dll")] public static extern int waveInPrepareHeader(IntPtr hWaveIn, ref WAVEHDR lpWaveHdr, uint Size); [DllImport("coredll.dll")] public static extern int waveInStart(IntPtr hWaveIn); // some other class private WinMM.WinMM.AudioRecordingDelegate waveIn; private IntPtr handle; private uint bufferLength; private void setupBuffer() { byte[] buffer = new byte[bufferLength]; GCHandle bufferPin = GCHandle.Alloc(buffer, GCHandleType.Pinned); WinMM.WinMM.WAVEHDR hdr = new WinMM.WinMM.WAVEHDR(); hdr.lpData = bufferPin.AddrOfPinnedObject(); hdr.dwBufferLength = this.bufferLength; hdr.dwFlags = 0; int i = WinMM.WinMM.waveInPrepareHeader(this.handle, ref hdr, Convert.ToUInt32(Marshal.SizeOf(hdr))); if (i != WinMM.WinMM.MMSYSERR_NOERROR) { this.Text = "Error: waveInPrepare"; return; } i = WinMM.WinMM.waveInAddBuffer(this.handle, ref hdr, Convert.ToUInt32(Marshal.SizeOf(hdr))); if (i != WinMM.WinMM.MMSYSERR_NOERROR) { this.Text = "Error: waveInAddrBuffer"; return; } } private void setupWaveIn() { WinMM.WinMM.WAVEFORMAT format = new WinMM.WinMM.WAVEFORMAT(); format.wFormatTag = WinMM.WinMM.WAVE_FORMAT_PCM; format.nChannels = 1; format.nSamplesPerSec = 8000; format.wBitsPerSample = 8; format.nBlockAlign = Convert.ToUInt16(format.nChannels * format.wBitsPerSample); format.nAvgBytesPerSec = format.nSamplesPerSec * format.nBlockAlign; this.bufferLength = format.nAvgBytesPerSec; format.cbSize = 0; int i = WinMM.WinMM.waveInOpen(out this.handle, WinMM.WinMM.WAVE_MAPPER, ref format, Marshal.GetFunctionPointerForDelegate(waveIn), 0, WinMM.WinMM.CALLBACK_FUNCTION); if (i != WinMM.WinMM.MMSYSERR_NOERROR) { this.Text = "Error: waveInOpen"; return; } setupBuffer(); WinMM.WinMM.waveInStart(this.handle); } I read alot about marshalling the last few days, nevertheless I do not get this code working. When my callback function is called (waveIn) when the buffer is full, the hdr structure passed back in wavehdr is obviously corrupted. Here is an examlpe of how the structure looks like at that point: - wavehdr {WinMM.WinMM.WAVEHDR} WinMM.WinMM.WAVEHDR dwBufferLength 0x19904c00 uint dwBytesRecorded 0x0000fa00 uint dwFlags 0x00000003 uint dwLoops 0x1990f6a4 uint + dwUser 0x00000000 System.IntPtr + lpData 0x00000000 System.IntPtr + lpNext 0x00000000 System.IntPtr + reserved 0x7c07c9a0 System.IntPtr This obiously is not what I expected to get passed. I am clearly concerned about the order of the fields in the view. I do not know if Visual Studio .NET cares about actual memory order when displaying the record in the "local"-view, but they are obviously not displayed in the order I speciefied in the struct. Then theres no data pointer and the bufferLength field is far to high. Interestingly the bytesRecorded field is exactly 64000 - bufferLength and bytesRecorded I'd expect both to be 64000 though. I do not know what exactly is going wrong, maybe someone can help me out on this. I'm an absolute noob to managed code programming and marshalling so please don't be too harsh to me for all the stupid things I've propably done. Oh here's the C code definition for WAVEHDR which I found here, I believe I might have done something wrong in the C# struct definition: /* wave data block header */ typedef struct wavehdr_tag { LPSTR lpData; /* pointer to locked data buffer */ DWORD dwBufferLength; /* length of data buffer */ DWORD dwBytesRecorded; /* used for input only */ DWORD_PTR dwUser; /* for client's use */ DWORD dwFlags; /* assorted flags (see defines) */ DWORD dwLoops; /* loop control counter */ struct wavehdr_tag FAR *lpNext; /* reserved for driver */ DWORD_PTR reserved; /* reserved for driver */ } WAVEHDR, *PWAVEHDR, NEAR *NPWAVEHDR, FAR *LPWAVEHDR; If you are used to work with all those low level tools like pointer-arithmetic, casts, etc starting writing managed code is a pain in the ass. It's like trying to learn how to swim with your hands tied on your back. Some things I tried (to no effect): .NET compact framework does not seem to support the Pack = 2^x directive in [StructLayout]. I tried [StructLayout(LayoutKind.Explicit)] and used 4 bytes and 8 bytes alignment. 4 bytes alignmentgave me the same result as the above code and 8 bytes alignment only made things worse - but that's what I expected. Interestingly if I move the code from setupBuffer into the setupWaveIn and do not declare the GCHandle in the context of the class but in a local context of setupWaveIn the struct returned by the callback function does not seem to be corrupted. I am not sure however why this is the case and how I can use this knowledge to fix my code. I'd really appreciate any good links on marshalling, calling unmanaged code from C#, etc. Then I'd be very happy if someone could point out my mistakes. What am I doing wrong? Why do I not get what I'd expect.

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• Dealing with external processes

  - by Jesse Aldridge

  I've been working on a gui app that needs to manage external processes. Working with external processes leads to a lot of issues that can make a programmer's life difficult. I feel like maintenence on this app is taking an unacceptably long time. I've been trying to list the things that make working with external processes difficult so that I can come up with ways of mitigating the pain. This kind of turned into a rant which I thought I'd post here in order to get some feedback and to provide some guidance to anybody thinking about sailing into these very murky waters. Here's what I've got so far: Output from the child can get mixed up with output from the parent. This can make both outputs misleading and hard to read. It can be hard to tell what came from where. It becomes harder to figure out what's going on when things are asynchronous. Here's a contrived example: import textwrap, os, time from subprocess import Popen test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) proc = Popen('python -B "%s"' % test_path) for i in range(3): print 'Hello %i' % i time.sleep(1) os.remove(test_path) I guess I could have the child process write its output to a file. But it can be annoying to have to open up a file every time I want to see the result of a print statement. If I have code for the child process I could add a label, something like print 'child: Hello %i', but it can be annoying to do that for every print. And it adds some noise to the output. And of course I can't do it if I don't have access to the code. I could manually manage the process output. But then you open up a huge can of worms with threads and polling and stuff like that. A simple solution is to treat processes like synchronous functions, that is, no further code executes until the process completes. In other words, make the process block. But that doesn't work if you're building a gui app. Which brings me to the next problem... Blocking processes cause the gui to become unresponsive. import textwrap, sys, os from subprocess import Popen from PyQt4.QtGui import * from PyQt4.QtCore import * test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) app = QApplication(sys.argv) button = QPushButton('Launch process') def launch_proc(): # Can't move the window until process completes proc = Popen('python -B "%s"' % test_path) proc.communicate() button.connect(button, SIGNAL('clicked()'), launch_proc) button.show() app.exec_() os.remove(test_path) Qt provides a process wrapper of its own called QProcess which can help with this. You can connect functions to signals to capture output relatively easily. This is what I'm currently using. But I'm finding that all these signals behave suspiciously like goto statements and can lead to spaghetti code. I think I want to get sort-of blocking behavior by having the 'finished' signal from QProcess call a function containing all the code that comes after the process call. I think that should work but I'm still a bit fuzzy on the details... Stack traces get interrupted when you go from the child process back to the parent process. If a normal function screws up, you get a nice complete stack trace with filenames and line numbers. If a subprocess screws up, you'll be lucky if you get any output at all. You end up having to do a lot more detective work everytime something goes wrong. Speaking of which, output has a way of disappearing when dealing external processes. Like if you run something via the windows 'cmd' command, the console will pop up, execute the code, and then disappear before you have a chance to see the output. You have to pass the /k flag to make it stick around. Similar issues seem to crop up all the time. I suppose both problems 3 and 4 have the same root cause: no exception handling. Exception handling is meant to be used with functions, it doesn't work with processes. Maybe there's some way to get something like exception handling for processes? I guess that's what stderr is for? But dealing with two different streams can be annoying in itself. Maybe I should look into this more... Processes can hang and stick around in the background without you realizing it. So you end up yelling at your computer cuz it's going so slow until you finally bring up your task manager and see 30 instances of the same process hanging out in the background. Also, hanging background processes can interefere with other instances of the process in various fun ways, such as causing permissions errors by holding a handle to a file or someting like that. It seems like an easy solution to this would be to have the parent process kill the child process on exit if the child process didn't close itself. But if the parent process crashes, cleanup code might not get called and the child can be left hanging. Also, if the parent waits for the child to complete, and the child is in an infinite loop or something, you can end up with two hanging processes. This problem can tie in to problem 2 for extra fun, causing your gui to stop responding entirely and force you to kill everything with the task manager. F***ing quotes Parameters often need to be passed to processes. This is a headache in itself. Especially if you're dealing with file paths. Say... 'C:/My Documents/whatever/'. If you don't have quotes, the string will often be split at the space and interpreted as two arguments. If you need nested quotes you can use ' and ". But if you need to use more than two layers of quotes, you have to do some nasty escaping, for example: "cmd /k 'python \'path 1\' \'path 2\''". A good solution to this problem is passing parameters as a list rather than as a single string. Subprocess allows you to do this. Can't easily return data from a subprocess. You can use stdout of course. But what if you want to throw a print in there for debugging purposes? That's gonna screw up the parent if it's expecting output formatted a certain way. In functions you can print one string and return another and everything works just fine. Obscure command-line flags and a crappy terminal based help system. These are problems I often run into when using os level apps. Like the /k flag I mentioned, for holding a cmd window open, who's idea was that? Unix apps don't tend to be much friendlier in this regard. Hopefully you can use google or StackOverflow to find the answer you need. But if not, you've got a lot of boring reading and frusterating trial and error to do. External factors. This one's kind of fuzzy. But when you leave the relatively sheltered harbor of your own scripts to deal with external processes you find yourself having to deal with the "outside world" to a much greater extent. And that's a scary place. All sorts of things can go wrong. Just to give a random example: the cwd in which a process is run can modify it's behavior. There are probably other issues, but those are the ones I've written down so far. Any other snags you'd like to add? Any suggestions for dealing with these problems?

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• Authoritative sources about Database vs. Flatfile decision

  - by FastAl

  <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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• java.lang.ArrayIndexOutOfBoundsException

  - by thefonso

  Here is the code. import java.applet.Applet; import java.awt.Button; import java.awt.Color; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class GuessingGame extends Applet{ /** * */ private static final long serialVersionUID = 1L; private final int START_X = 20; private final int START_Y = 40; private final int ROWS = 4; private final int COLS = 4; private final int BOX_WIDTH = 20; private final int BOX_HEIGHT = 20; //this is used to keep track of boxes that have been matched. private boolean matchedBoxes[][]; //this is used to keep track of two boxes that have been clicked. private MaskableBox chosenBoxes[]; private MaskableBox boxes[][]; private Color boxColors[][]; private Button resetButton; public void init() { boxes = new MaskableBox[ROWS][COLS]; boxColors = new Color[ROWS][COLS]; resetButton = new Button("Reset Colors"); resetButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { randomizeColors(); buildBoxes(); repaint(); } }); add(resetButton); //separate building colors so we can add a button later //to re-randomize them. randomizeColors(); buildBoxes(); } public void paint(Graphics g) { for (int row =0; row < boxes.length; row ++) { for (int col = 0; col < boxes[row].length; col++) { if(boxes[row][col].isClicked()) { //boxes[row][col].setMaskColor(Color.black); //boxes[row][col].setMask(!boxes[row][col].isMask()); //boxes[row][col].setClicked(false); //} if (!matchedBoxes[row][col]) { gameLogic(boxes[row][col]); //boxes[row][col].draw(g); } } } } //loop through the boxes and draw them. for (int row = 0; row < boxes.length; row++) { for (int col = 0; col < boxes[row].length; col++) { boxes[row][col].draw(g); } } } public void gameLogic(MaskableBox box) { if ((chosenBoxes[0] != null)&&(chosenBoxes[1] != null)) { if(chosenBoxes[0].getBackColor() == chosenBoxes[1].getBackColor()) { for (int i=0; 0 <= chosenBoxes.length; ++i ) { for(int row = 0; row < boxes.length; row++) { for(int col = 0; col < boxes[row].length; col++) { if( boxes[row][col] == chosenBoxes[i] ) { System.out.println("boxes [row][col] == chosenBoxes[] at index: " + i ); matchedBoxes[row][col] = true; break; } } } } }else { chosenBoxes[0].setMask(true); chosenBoxes[1].setMask(true); } chosenBoxes = new MaskableBox[2]; }else { if (chosenBoxes[0] == null) { chosenBoxes[0] = box; chosenBoxes[0].setMask(false); return; }else{ if (chosenBoxes[1] == null) { chosenBoxes[1] = box; chosenBoxes[1].setMask(false); } } } } private void removeMouseListeners() { for(int row = 0; row < boxes.length; row ++) { for(int col = 0; col < boxes[row].length; col++) { removeMouseListener(boxes[row][col]); } } } private void buildBoxes() { // need to clear any chosen boxes when building new array. chosenBoxes = new MaskableBox[2]; // create a new matchedBoxes array matchedBoxes = new boolean [ROWS][COLS]; removeMouseListeners(); for(int row = 0; row < boxes.length; row++) { for(int col = 0; col < boxes[row].length; col++) { boxes[row][col] = new MaskableBox(START_X + col * BOX_WIDTH, START_Y + row * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT, Color.gray, boxColors[row][col], true, true, this); addMouseListener(boxes[row][col]); } } } private void randomizeColors() { int[] chosenColors = {0,0,0,0,0,0,0,0}; Color[] availableColors = {Color.red, Color.blue, Color.green, Color.yellow, Color.cyan, Color.magenta, Color.pink, Color.orange }; for(int row = 0; row < boxes.length; row++) { for (int col = 0; col < boxes[row].length; col++) { for (;;) { int rnd = (int) (Math.random() * 8); if (chosenColors[rnd]< 2) { chosenColors[rnd]++; boxColors[row][col] = availableColors[rnd]; break; } } } } } } here is the second batch of code containing maskablebox import java.awt.Color; import java.awt.Container; import java.awt.Graphics; public class MaskableBox extends ClickableBox { private boolean mask; private Color maskColor; Container parent; public MaskableBox(int x, int y, int width, int height, Color borderColor, Color backColor, boolean drawBorder, boolean mask, Container parent ) { super(x, y, width, height, borderColor, backColor, drawBorder, parent); this.parent = parent; this.mask = mask; } public void draw(Graphics g) { if(mask=false) { super.draw(g); // setOldColor(g.getColor()); // g.setColor(maskColor); // g.fillRect(getX(),getY(),getWidth(), getHeight()); // if(isDrawBorder()) { // g.setColor(getBorderColor()); // g.drawRect(getX(),getY(),getWidth(),getHeight()); // } // g.setColor(getOldColor()); }else { if(mask=true) { //super.draw(g); setOldColor(g.getColor()); g.setColor(maskColor); g.fillRect(getX(),getY(),getWidth(), getHeight()); if(isDrawBorder()) { g.setColor(getBorderColor()); g.drawRect(getX(),getY(),getWidth(),getHeight()); } g.setColor(getOldColor()); } } } public boolean isMask() { return mask; } public void setMask(boolean mask) { this.mask = mask; } public Color getMaskColor() { return maskColor; } public void setMaskColor(Color maskColor) { this.maskColor = maskColor; } } I keep getting these error messages. I'm going nuts trying to figure this out. can anyone tell me what I'm doing wrong? boxes [row][col] == chosenBoxes[] at index: 0 boxes [row][col] == chosenBoxes[] at index: 1 Exception in thread "AWT-EventQueue-1" java.lang.ArrayIndexOutOfBoundsException: 2 at GuessingGame.gameLogic(GuessingGame.java:77) at GuessingGame.paint(GuessingGame.java:55) at java.awt.Container.update(Container.java:1801) at sun.awt.RepaintArea.updateComponent(RepaintArea.java:239) at sun.awt.RepaintArea.paint(RepaintArea.java:216) at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:306) at java.awt.Component.dispatchEventImpl(Component.java:4706) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

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• parseInt and viewflipper layout problems

  - by user1234167

  I have a problem with parseInt it throws the error: unable to parse 'null' as integer. My view flipper is also not working. Hopefully this is an easy enough question. Here is my activity: import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.InputSource; import org.xml.sax.XMLReader; import android.app.Activity; import android.graphics.Color; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.LinearLayout; import android.widget.TextView; import android.widget.ViewFlipper; import xml.parser.dataset; public class XmlParserActivity extends Activity implements OnClickListener { private final String MY_DEBUG_TAG = "WeatherForcaster"; // private dataset myDataSet; private LinearLayout layout; private int temp= 0; /** Called when the activity is first created. */ //the ViewSwitcher private Button btn; private ViewFlipper flip; // private TextView tv; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); layout=(LinearLayout)findViewById(R.id.linearlayout1); btn=(Button)findViewById(R.id.btn); btn.setOnClickListener(this); flip=(ViewFlipper)findViewById(R.id.flip); //when a view is displayed flip.setInAnimation(this,android.R.anim.fade_in); //when a view disappears flip.setOutAnimation(this, android.R.anim.fade_out); // String postcode = null; // public String getPostcode { // return postcode; // } //URL newUrl = c; // myweather.setText(c.toString()); /* Create a new TextView to display the parsingresult later. */ TextView tv = new TextView(this); // run(0); //WeatherApplicationActivity postcode = new WeatherApplicationActivity(); try { /* Create a URL we want to load some xml-data from. */ URL url = new URL("http://new.myweather2.com/developer/forecast.ashx?uac=gcV3ynNdoV&output=xml&query=G41"); //String url = new String("http://new.myweather2.com/developer/forecast.ashx?uac=gcV3ynNdoV&output=xml&query="+WeatherApplicationActivity.postcode ); //URL url = new URL(url); //url.toString( ); //myString(url.toString() + WeatherApplicationActivity.getString(postcode)); // url + WeatherApplicationActivity.getString(postcode); /* Get a SAXParser from the SAXPArserFactory. */ SAXParserFactory spf = SAXParserFactory.newInstance(); SAXParser sp = spf.newSAXParser(); /* Get the XMLReader of the SAXParser we created. */ XMLReader xr = sp.getXMLReader(); /* Create a new ContentHandler and apply it to the XML-Reader*/ handler myHandler = new handler(); xr.setContentHandler(myHandler); /* Parse the xml-data from our URL. */ xr.parse(new InputSource(url.openStream())); /* Parsing has finished. */ /* Our ExampleHandler now provides the parsed data to us. */ dataset parsedDataSet = myHandler.getParsedData(); /* Set the result to be displayed in our GUI. */ tv.setText(parsedDataSet.toString()); } catch (Exception e) { /* Display any Error to the GUI. */ tv.setText("Error: " + e.getMessage()); Log.e(MY_DEBUG_TAG, "WeatherQueryError", e); } temp = Integer.parseInt(xml.parser.dataset.getTemp()); if(temp <0){ //layout.setBackgroundColor(Color.BLUE); //layout.setBackgroundColor(getResources().getColor(R.color.silver)); findViewById(R.id.flip).setBackgroundColor(Color.BLUE); } else if(temp > 0 && temp < 9) { //layout.setBackgroundColor(Color.GREEN); //layout.setBackgroundColor(getResources().getColor(R.color.silver)); findViewById(R.id.flip).setBackgroundColor(Color.GREEN); } else { //layout.setBackgroundColor(Color.YELLOW); //layout.setBackgroundColor(getResources().getColor(R.color.silver)); findViewById(R.id.flip).setBackgroundColor(Color.YELLOW); } /* Display the TextView. */ this.setContentView(tv); } @Override public void onClick(View arg0) { // TODO Auto-generated method stub onClick(View arg0) { // TODO Auto-generated method stub flip.showNext(); //specify flipping interval //flip.setFlipInterval(1000); //flip.startFlipping(); } } this is my dataset: package xml.parser; public class dataset { static String temp = null; // private int extractedInt = 0; public static String getTemp() { return temp; } public void setTemp(String temp) { this.temp = temp; } this is my handler: public void characters(char ch[], int start, int length) { if(this.in_temp){ String setTemp = new String(ch, start, length); // myParsedDataSet.setTempUnit(new String(ch, start, length)); // myParsedDataSet.setTemp; } the dataset and handler i only pasted the code that involves the temp as i no they r working when i take out the if statement. However even then my viewflipper wont work. This is my main xml: <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/linearlayout1" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="25dip" android:text="Flip Example" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="25dip" android:id="@+id/tv" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="25dip" android:text="Flip" android:id="@+id/btn" android:onClick="ClickHandler" /> <ViewFlipper android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/flip"> <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="25dip" android:text="Item1a" /> </LinearLayout> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="25dip" android:id="@+id/tv2" /> </ViewFlipper> </LinearLayout> this is my logcat: 04-01 18:02:24.744: E/AndroidRuntime(7331): FATAL EXCEPTION: main 04-01 18:02:24.744: E/AndroidRuntime(7331): java.lang.RuntimeException: Unable to start activity ComponentInfo{xml.parser/xml.parser.XmlParserActivity}: java.lang.NumberFormatException: unable to parse 'null' as integer 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1830) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1851) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread.access$1500(ActivityThread.java:132) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1038) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.os.Handler.dispatchMessage(Handler.java:99) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.os.Looper.loop(Looper.java:150) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread.main(ActivityThread.java:4293) 04-01 18:02:24.744: E/AndroidRuntime(7331): at java.lang.reflect.Method.invokeNative(Native Method) 04-01 18:02:24.744: E/AndroidRuntime(7331): at java.lang.reflect.Method.invoke(Method.java:507) 04-01 18:02:24.744: E/AndroidRuntime(7331): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849) 04-01 18:02:24.744: E/AndroidRuntime(7331): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607) 04-01 18:02:24.744: E/AndroidRuntime(7331): at dalvik.system.NativeStart.main(Native Method) 04-01 18:02:24.744: E/AndroidRuntime(7331): Caused by: java.lang.NumberFormatException: unable to parse 'null' as integer 04-01 18:02:24.744: E/AndroidRuntime(7331): at java.lang.Integer.parseInt(Integer.java:356) 04-01 18:02:24.744: E/AndroidRuntime(7331): at java.lang.Integer.parseInt(Integer.java:332) 04-01 18:02:24.744: E/AndroidRuntime(7331): at xml.parser.XmlParserActivity.onCreate(XmlParserActivity.java:118) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072) 04-01 18:02:24.744: E/AndroidRuntime(7331): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1794) I hope I have given enough information about my problems. I will be extremely grateful if anyone can help me out.

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• how to store data in ram in verilog

  - by anum

  i am having a bit stream of 128 bits @ each posedge of clk,i.e.total 10 bit streams each of length 128 bits. i want to divide the 128 bit stream into 8, 8 bits n hve to store them in a ram / memory of width 8 bits. i did it by assigning 8, 8 bits to wires of size 8 bit.in this way there are 16 wires. and i am using dual port ram...wen i cal module of memory in stimulus.i don know how to give input....as i am hving 16 different wires naming from k1 to k16. **codeeee** // this is stimulus file module final_stim; reg [7:0] in,in_data; reg clk,rst_n,rd,wr,rd_data,wr_data; wire [7:0] out,out_wr, ouut; wire[7:0] d; integer i; //wire[7:0] xor_out; reg kld,f; reg [127:0]key; wire [127:0] key_expand; wire [7:0]out_data; reg [7:0] k; //wire [7:0] k1,k2,k3,k4,k5,k6,k7,k8,k9,k10,k11,k12,k13,k14,k15,k16; wire [7:0] out_data1; **//key_expand is da output which is giving 10 streams of size 128 bits.** assign k1=key_expand[127:120]; assign k2=key_expand[119:112]; assign k3=key_expand[111:104]; assign k4=key_expand[103:96]; assign k5=key_expand[95:88]; assign k6=key_expand[87:80]; assign k7=key_expand[79:72]; assign k8=key_expand[71:64]; assign k9=key_expand[63:56]; assign k10=key_expand[55:48]; assign k11=key_expand[47:40]; assign k12=key_expand[39:32]; assign k13=key_expand[31:24]; assign k14=key_expand[23:16]; assign k15=key_expand[15:8]; assign k16=key_expand[7:0]; **// then the module of memory is instanciated. //here k1 is sent as input.but i don know how to save the other values of k. //i tried to use for loop but it dint help** memory m1(clk,rst_n,rd, wr,k1,out_data1); aes_sbox b(out,d); initial begin clk=1'b1; rst_n=1'b0; #20 rst_n = 1; //rd=1'b1; wr_data=1'b1; in=8'hd4; #20 //rst_n=1'b1; in=8'h27; rd_data=1'b0; wr_data=1'b1; #20 in=8'h11; rd_data=1'b0; wr_data=1'b1; #20 in=8'hae; rd_data=1'b0; wr_data=1'b1; #20 in=8'he0; rd_data=1'b0; wr_data=1'b1; #20 in=8'hbf; rd_data=1'b0; wr_data=1'b1; #20 in=8'h98; rd_data=1'b0; wr_data=1'b1; #20 in=8'hf1; rd_data=1'b0; wr_data=1'b1; #20 in=8'hb8; rd_data=1'b0; wr_data=1'b1; #20 in=8'hb4; rd_data=1'b0; wr_data=1'b1; #20 in=8'h5d; rd_data=1'b0; wr_data=1'b1; #20 in=8'he5; rd_data=1'b0; wr_data=1'b1; #20 in=8'h1e; rd_data=1'b0; wr_data=1'b1; #20 in=8'h41; rd_data=1'b0; wr_data=1'b1; #20 in=8'h52; rd_data=1'b0; wr_data=1'b1; #20 in=8'h30; rd_data=1'b0; wr_data=1'b1; #20 wr_data=1'b0; #380 rd_data=1'b1; #320 rd_data = 1'b0; /////////////// #10 kld = 1'b1; key=128'h 2b7e151628aed2a6abf7158809cf4f3c; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b0; #10 wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 kld = 1'b0; key = 128'h 2b7e151628aed2a6abf7158809cf4f3c; wr = 1'b1; rd = 1'b1; #20 wr = 1'b0; #20 rd = 1'b1; #4880 f=1'b1; ///////////////////////////////////////////////// // out_data[i] end /*always@(*) begin while(i) mem[i]^mem1[i] ; i<=16; break; end*/ always #10 clk=~clk; always@(posedge clk) begin //$monitor($time," out_wr=%h,out_rd=%h\n ",out_wr,out); #10000 $stop; end endmodule

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• Network Data Packet connectivity intent

  - by Rakesh

  I am writing an Android application which can enable and disable the Network Data packet connection. I am also using one broadcast receiver to check the Network Data packet connection. I have registered broadcast receiver and provided required permission in Manifest file. But when I run this application it changes the connection state and after that it crashes. But when I don't include this broadcast receiver it works fine. I am not able to see any kind of log which can provide some clue. Here is my code for broadcast receiver. <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.rakesh.simplewidget" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="10" /> <!-- Permissions --> <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" /> <uses-permission android:name="android.permission.MODIFY_PHONE_STATE" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:name=".SimpleWidgetExampleActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <!-- <receiver android:name=".ExampleAppWidgetProvider" android:label="Widget ErrorBuster" > <intent-filter> <action android:name="android.appwidget.action.APPWIDGET_UPDATE" /> </intent-filter> <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget1_info" /> </receiver> --> <receiver android:name=".ConnectivityReceiver" > <intent-filter> <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> </intent-filter> </receiver> </application> </manifest> My Broadcast receiver class is as following. import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.util.Log; public class ConnectivityReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { NetworkInfo info = (NetworkInfo)intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO); if(info.getType() == ConnectivityManager.TYPE_MOBILE){ if(info.isConnectedOrConnecting()){ Log.e("RK","Mobile data is connected"); }else{ Log.e("RK","Mobile data is disconnected"); } } } } my Main activity file. package com.rakesh.simplewidget; import java.lang.reflect.Field; import java.lang.reflect.Method; import android.app.Activity; import android.content.Context; import android.content.Intent; import android.graphics.Color; import android.net.ConnectivityManager; import android.os.Bundle; import android.telephony.TelephonyManager; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.Toast; public class SimpleWidgetExampleActivity extends Activity { private Button btNetworkSetting; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btNetworkSetting = (Button)findViewById(R.id.btNetworkSetting); if(checkConnectivityState(getApplicationContext())){ btNetworkSetting.setBackgroundColor(Color.GREEN); }else{ btNetworkSetting.setBackgroundColor(Color.GRAY); } } public void openNetworkSetting(View view){ Method dataConnSwitchmethod; Class telephonyManagerClass; Object ITelephonyStub; Class ITelephonyClass; Context context = view.getContext(); boolean enabled = !checkConnectivityState(context); final ConnectivityManager conman = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); try{ final Class conmanClass = Class.forName(conman.getClass().getName()); final Field iConnectivityManagerField = conmanClass.getDeclaredField("mService"); iConnectivityManagerField.setAccessible(true); final Object iConnectivityManager = iConnectivityManagerField.get(conman); final Class iConnectivityManagerClass = Class.forName(iConnectivityManager.getClass().getName()); final Method setMobileDataEnabledMethod = iConnectivityManagerClass.getDeclaredMethod("setMobileDataEnabled", Boolean.TYPE); setMobileDataEnabledMethod.setAccessible(true); setMobileDataEnabledMethod.invoke(iConnectivityManager, enabled); if(enabled){ Toast.makeText(view.getContext(), "Enabled Network Data", Toast.LENGTH_LONG).show(); view.setBackgroundColor(Color.GREEN); } else{ Toast.makeText(view.getContext(), "Disabled Network Data", Toast.LENGTH_LONG).show(); view.setBackgroundColor(Color.LTGRAY); } }catch(Exception e){ Log.e("Error", "some error"); Toast.makeText(view.getContext(), "It didn't work", Toast.LENGTH_LONG).show(); } } private boolean checkConnectivityState(Context context){ final TelephonyManager telephonyManager = (TelephonyManager) context .getSystemService(Context.TELEPHONY_SERVICE); ConnectivityManager af ; return telephonyManager.getDataState() == TelephonyManager.DATA_CONNECTED; } } Log file: java.lang.RuntimeException: Unable to instantiate receiver com.rakesh.simplewidget.ConnectivityReceiver: java.lang.ClassNotFoundException: com.rakesh.simplewidget.ConnectivityReceiver in loader dalvik.system.PathClassLoader[/data/app/com.rakesh.simplewidget-2.apk] E/AndroidRuntime(26094): at android.app.ActivityThread.handleReceiver(ActivityThread.java:1777) E/AndroidRuntime(26094): at android.app.ActivityThread.access$2400(ActivityThread.java:117) E/AndroidRuntime(26094): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:985) E/AndroidRuntime(26094): at android.os.Handler.dispatchMessage(Handler.java:99) E/AndroidRuntime(26094): at android.os.Looper.loop(Looper.java:130) E/AndroidRuntime(26094): at android.app.ActivityThread.main(ActivityThread.java:3691) E/AndroidRuntime(26094): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime(26094): at java.lang.reflect.Method.invoke(Method.java:507) E/AndroidRuntime(26094): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907) E/AndroidRuntime(26094): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665) E/AndroidRuntime(26094): at dalvik.system.NativeStart.main(Native Method) It seems Android is not able to recognize file Broadcast Receiver class. Any idea why I am getting this error? PS: Some information about Android environment and platform. - Android API 10. - Running on Samsung Galaxy II which has android 2.3.6 Edit: my broadcast receiver file ConnectivityReceiver.java was present in default package and it was not being recognized by Android. Android was looking for this file in current package i.e com.rakesh.simplewidget; I just moved connectivityReciever.java file to com.rakesh.simplewidget package and problem was solved.

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• Repaint window problems

  - by nXqd

  #include "stdafx.h" // Mario Headers #include "GameMain.h" #define MAX_LOADSTRING 100 // Global Variables: HINSTANCE hInst; // current instance TCHAR szTitle[MAX_LOADSTRING]; // The title bar text TCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name // Mario global variables ================= CGameMain* gGameMain; HWND hWnd; PAINTSTRUCT ps; // ======================================== // Forward declarations of functions included in this code module: ATOM MyRegisterClass(HINSTANCE hInstance); BOOL InitInstance(HINSTANCE, int); LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM); // My unprocess function ===================================== void OnCreate(HWND hWnd) { } void OnKeyUp(WPARAM wParam) { switch (wParam) { case VK_LEFT: gGameMain->KeyReleased(LEFT); break; case VK_UP: gGameMain->KeyReleased(UP); break; case VK_RIGHT: gGameMain->KeyReleased(RIGHT); break; case VK_DOWN: gGameMain->KeyReleased(DOWN); break; } } void OnKeyDown(HWND hWnd,WPARAM wParam) { switch (wParam) { case VK_LEFT: gGameMain->KeyPressed(LEFT); break; case VK_UP: gGameMain->KeyPressed(UP); break; case VK_RIGHT: gGameMain->KeyPressed(RIGHT); break; case VK_DOWN: gGameMain->KeyPressed(DOWN); break; } } void OnPaint(HWND hWnd) { HDC hdc = BeginPaint(hWnd,&ps); RECT rect; GetClientRect(hWnd,&rect); HDC hdcDouble = CreateCompatibleDC(hdc); HBITMAP hdcBitmap = CreateCompatibleBitmap(hdc,rect.right,rect.bottom); HBITMAP bmOld = (HBITMAP)SelectObject(hdcDouble, hdcBitmap); gGameMain->SetHDC(&hdcDouble); gGameMain->SendMessage(MESSAGE_PAINT); BitBlt(hdc,0,0,rect.right,rect.bottom,hdcDouble,0,0,SRCCOPY); SelectObject(hdcDouble,bmOld); DeleteDC(hdcDouble); DeleteObject(hdcBitmap); DeleteDC(hdc); } void OnDestroy() { gGameMain->isPlaying = false; EndPaint(hWnd,&ps); } // My unprocess function ===================================== ATOM MyRegisterClass(HINSTANCE hInstance) { WNDCLASSEX wcex; wcex.cbSize = sizeof(WNDCLASSEX); wcex.style = CS_HREDRAW | CS_VREDRAW; wcex.lpfnWndProc = WndProc; wcex.cbClsExtra = 0; wcex.cbWndExtra = 0; wcex.hInstance = hInstance; wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_GDIMARIO)); wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); wcex.lpszMenuName = MAKEINTRESOURCE(IDC_GDIMARIO); wcex.lpszClassName = szWindowClass; wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL)); return RegisterClassEx(&wcex); } BOOL InitInstance(HINSTANCE hInstance, int nCmdShow) { hInst = hInstance; // Store instance handle in our global variable hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, WIDTH, HEIGHT, 0, NULL, hInstance, NULL); if (!hWnd) { return FALSE; } // ---------------- Start gdiplus ------------------ GdiplusStartup(&gdiToken,&gdiStartInput,NULL); // ------------------------------------------------- // Init GameMain gGameMain = new CGameMain(); ShowWindow(hWnd, nCmdShow); UpdateWindow(hWnd); return TRUE; } LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent; switch (message) { case WM_COMMAND: wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_KEYDOWN: OnKeyDown(hWnd,wParam); break; case WM_KEYUP: OnKeyUp(wParam); break; case WM_CREATE: OnCreate(hWnd); break; case WM_PAINT: OnPaint(hWnd); break; case WM_DESTROY: OnDestroy(); PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0; } // Message handler for about box. INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE; } int APIENTRY _tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR lpCmdLine,int nCmdShow) { UNREFERENCED_PARAMETER(hPrevInstance); UNREFERENCED_PARAMETER(lpCmdLine); // TODO: Place code here. MSG msg; HACCEL hAccelTable; // Initialize global strings LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING); LoadString(hInstance, IDC_GDIMARIO, szWindowClass, MAX_LOADSTRING); MyRegisterClass(hInstance); // Perform application initialization: if (!InitInstance (hInstance, nCmdShow)) { return FALSE; } hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_GDIMARIO)); // Main message loop: // GameLoop PeekMessage(&msg,NULL,0,0,PM_NOREMOVE); while (gGameMain->isPlaying) { while (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) { if (msg.message == WM_QUIT) break; TranslateMessage(&msg); DispatchMessage(&msg); } if (gGameMain->enterNextState) { gGameMain->SendMessage(MESSAGE_ENTER); gGameMain->enterNextState = false; } gGameMain->SendMessage(MESSAGE_UPDATE); InvalidateRect(hWnd,NULL,FALSE); /*if (gGameMain->exitCurrentState) { gGameMain->SendMessage(MESSAGE_EXIT); gGameMain->enterNextState = true; gGameMain->exitCurrentState = false; }*/ ::Sleep(gGameMain->timer); // Do your game stuff here } GdiplusShutdown(gdiToken); // Shut down gdiplus token return (int) msg.wParam; } I use InvalidateRect(hWnd,NULL,FALSE); for repaint window, but the problem I met is when I repaint without any changes in Game struct . First it paints my logo well, the second time ( just call InvalidateRect(hWnd,NULL,FALSE); without gGameMain-SendMessage(MESSAGE_ENTER); which is init some variables for painting . Thanks for reading this :)

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• g++ SSE intrinsics dilemma - value from intrinsic "saturates"

  - by Sriram

  Hi, I wrote a simple program to implement SSE intrinsics for computing the inner product of two large (100000 or more elements) vectors. The program compares the execution time for both, inner product computed the conventional way and using intrinsics. Everything works out fine, until I insert (just for the fun of it) an inner loop before the statement that computes the inner product. Before I go further, here is the code: //this is a sample Intrinsics program to compute inner product of two vectors and compare Intrinsics with traditional method of doing things. #include <iostream> #include <iomanip> #include <xmmintrin.h> #include <stdio.h> #include <time.h> #include <stdlib.h> using namespace std; typedef float v4sf __attribute__ ((vector_size(16))); double innerProduct(float* arr1, int len1, float* arr2, int len2) { //assume len1 = len2. float result = 0.0; for(int i = 0; i < len1; i++) { for(int j = 0; j < len1; j++) { result += (arr1[i] * arr2[i]); } } //float y = 1.23e+09; //cout << "y = " << y << endl; return result; } double sse_v4sf_innerProduct(float* arr1, int len1, float* arr2, int len2) { //assume that len1 = len2. if(len1 != len2) { cout << "Lengths not equal." << endl; exit(1); } /*steps: * 1. load a long-type (4 float) into a v4sf type data from both arrays. * 2. multiply the two. * 3. multiply the same and store result. * 4. add this to previous results. */ v4sf arr1Data, arr2Data, prevSums, multVal, xyz; //__builtin_ia32_xorps(prevSums, prevSums); //making it equal zero. //can explicitly load 0 into prevSums using loadps or storeps (Check). float temp[4] = {0.0, 0.0, 0.0, 0.0}; prevSums = __builtin_ia32_loadups(temp); float result = 0.0; for(int i = 0; i < (len1 - 3); i += 4) { for(int j = 0; j < len1; j++) { arr1Data = __builtin_ia32_loadups(&arr1[i]); arr2Data = __builtin_ia32_loadups(&arr2[i]); //store the contents of two arrays. multVal = __builtin_ia32_mulps(arr1Data, arr2Data); //multiply. xyz = __builtin_ia32_addps(multVal, prevSums); prevSums = xyz; } } //prevSums will hold the sums of 4 32-bit floating point values taken at a time. Individual entries in prevSums also need to be added. __builtin_ia32_storeups(temp, prevSums); //store prevSums into temp. cout << "Values of temp:" << endl; for(int i = 0; i < 4; i++) cout << temp[i] << endl; result += temp[0] + temp[1] + temp[2] + temp[3]; return result; } int main() { clock_t begin, end; int length = 100000; float *arr1, *arr2; double result_Conventional, result_Intrinsic; // printStats("Allocating memory."); arr1 = new float[length]; arr2 = new float[length]; // printStats("End allocation."); srand(time(NULL)); //init random seed. // printStats("Initializing array1 and array2"); begin = clock(); for(int i = 0; i < length; i++) { // for(int j = 0; j < length; j++) { // arr1[i] = rand() % 10 + 1; arr1[i] = 2.5; // arr2[i] = rand() % 10 - 1; arr2[i] = 2.5; // } } end = clock(); cout << "Time to initialize array1 and array2 = " << ((double) (end - begin)) / CLOCKS_PER_SEC << endl; // printStats("Finished initialization."); // printStats("Begin inner product conventionally."); begin = clock(); result_Conventional = innerProduct(arr1, length, arr2, length); end = clock(); cout << "Time to compute inner product conventionally = " << ((double) (end - begin)) / CLOCKS_PER_SEC << endl; // printStats("End inner product conventionally."); // printStats("Begin inner product using Intrinsics."); begin = clock(); result_Intrinsic = sse_v4sf_innerProduct(arr1, length, arr2, length); end = clock(); cout << "Time to compute inner product with intrinsics = " << ((double) (end - begin)) / CLOCKS_PER_SEC << endl; //printStats("End inner product using Intrinsics."); cout << "Results: " << endl; cout << " result_Conventional = " << result_Conventional << endl; cout << " result_Intrinsics = " << result_Intrinsic << endl; return 0; } I use the following g++ invocation to build this: g++ -W -Wall -O2 -pedantic -march=i386 -msse intrinsics_SSE_innerProduct.C -o innerProduct Each of the loops above, in both the functions, runs a total of N^2 times. However, given that arr1 and arr2 (the two floating point vectors) are loaded with a value 2.5, the length of the array is 100,000, the result in both cases should be 6.25e+10. The results I get are: Results: result_Conventional = 6.25e+10 result_Intrinsics = 5.36871e+08 This is not all. It seems that the value returned from the function that uses intrinsics "saturates" at the value above. I tried putting other values for the elements of the array and different sizes too. But it seems that any value above 1.0 for the array contents and any size above 1000 meets with the same value we see above. Initially, I thought it might be because all operations within SSE are in floating point, but floating point should be able to store a number that is of the order of e+08. I am trying to see where I could be going wrong but cannot seem to figure it out. I am using g++ version: g++ (GCC) 4.4.1 20090725 (Red Hat 4.4.1-2). Any help on this is most welcome. Thanks, Sriram.

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• How do I prove I should put a table of values in source code instead of a database table?

  - by FastAl

  <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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• (PHP) Validation, Security and Speed - Does my app have these?

  - by Devner

  Hi all, I am currently working on a building community website in PHP. This contains forms that a user can fill right from registration to lot of other functionality. I am not an Object-oriented guy, so I am using functions most of the time to handle my application. I know I have to learn OOPS, but currently need to develop this website and get it running soon. Anyway, here's a sample of what I let my app. do: Consider a page (register.php) that has a form where a user has 3 fields to fill up, say: First Name, Last Name and Email. Upon submission of this form, I want to validate the form and show the corresponding errors to the users: <form id="form1" name="form1" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>"> <label for="name">Name:</label> <input type="text" name="name" id="name" /><br /> <label for="lname">Last Name:</label> <input type="text" name="lname" id="lname" /><br /> <label for="email">Email:</label> <input type="text" name="email" id="email" /><br /> <input type="submit" name="submit" id="submit" value="Submit" /> </form> This form will POST the info to the same page. So here's the code that will process the POST'ed info: <?php require("functions.php"); if( isset($_POST['submit']) ) { $errors = fn_register(); if( count($errors) ) { //Show error messages } else { //Send welcome mail to the user or do database stuff... } } ?> <?php //functions.php page: function sql_quote( $value ) { if( get_magic_quotes_gpc() ) { $value = stripslashes( $value ); } else { $value = addslashes( $value ); } if( function_exists( "mysql_real_escape_string" ) ) { $value = mysql_real_escape_string( $value ); } return $value; } function clean($str) { $str = strip_tags($str, '<br>,<br />'); $str = trim($str); $str = sql_quote($str); return $str; } foreach ($_POST as &$value) { if (!is_array($value)) { $value = clean($value); } else { clean($value); } } foreach ($_GET as &$value) { if (!is_array($value)) { $value = clean($value); } else { clean($value); } } function validate_name( $fld, $min, $max, $rule, $label ) { if( $rule == 'required' ) { if ( trim($fld) == '' ) { $str = "$label: Cannot be left blank."; return $str; } } if ( isset($fld) && trim($fld) != '' ) { if ( isset($fld) && $fld != '' && !preg_match("/^[a-zA-Z\ ]+$/", $fld)) { $str = "$label: Invalid characters used! Only Lowercase, Uppercase alphabets and Spaces are allowed"; } else if ( strlen($fld) < $min or strlen($fld) > $max ) { $curr_char = strlen($fld); $str = "$label: Must be atleast $min character &amp; less than $max char. Entered characters: $curr_char"; } else { $str = 0; } } else { $str = 0; } return $str; } function validate_email( $fld, $min, $max, $rule, $label ) { if( $rule == 'required' ) { if ( trim($fld) == '' ) { $str = "$label: Cannot be left blank."; return $str; } } if ( isset($fld) && trim($fld) != '' ) { if ( !eregi('^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.([a-zA-Z]{2,4})$', $fld) ) { $str = "$label: Invalid format. Please check."; } else if ( strlen($fld) < $min or strlen($fld) > $max ) { $curr_char = strlen($fld); $str = "$label: Must be atleast $min character &amp; less than $max char. Entered characters: $curr_char"; } else { $str = 0; } } else { $str = 0; } return $str; } function val_rules( $str, $val_type, $rule='required' ){ switch ($val_type) { case 'name': $val = validate_name( $str, 3, 20, $rule, 'First Name'); break; case 'lname': $val = validate_name( $str, 10, 20, $rule, 'Last Name'); break; case 'email': $val = validate_email( $str, 10, 60, $rule, 'Email'); break; } return $val; } function fn_register() { $errors = array(); $val_name = val_rules( $_POST['name'], 'name' ); $val_lname = val_rules( $_POST['lname'], 'lname', 'optional' ); $val_email = val_rules( $_POST['email'], 'email' ); if ( $val_name != '0' ) { $errors['name'] = $val_name; } if ( $val_lname != '0' ) { $errors['lname'] = $val_lname; } if ( $val_email != '0' ) { $errors['email'] = $val_email; } return $errors; } //END of functions.php page ?> OK, now it might look like there's a lot, but lemme break it down target wise: 1. I wanted the foreach ($_POST as &$value) and foreach ($_GET as &$value) loops to loop through the received info from the user submission and strip/remove all malicious input. I am calling a function called clean on the input first to achieve the objective as stated above. This function will process each of the input, whether individual field values or even arrays and allow only tags and remove everything else. The rest of it is obvious. Once this happens, the new/cleaned values will be processed by the fn_register() function and based on the values returned after the validation, we get the corresponding errors or NULL values (as applicable). So here's my questions: 1. This pretty much makes me feel secure as I am forcing the user to correct malicious data and won't process the final data unless the errors are corrected. Am I correct? Does the method that I follow guarantee the speed (as I am using lots of functions and their corresponding calls)? The fields of a form differ and the minimum number of fields I may have at any given point of time in any form may be 3 and can go upto as high as 100 (or even more, I am not sure as the website is still being developed). Will having 100's of fields and their validation in the above way, reduce the speed of application (say upto half a million users are accessing the website at the same time?). What can I do to improve the speed and reduce function calls (if possible)? 3, Can I do something to improve the current ways of validation? I am holding off object oriented approach and using FILTERS in PHP for the later. So please, I request you all to suggest me way to improve/tweak the current ways and suggest me if the script is vulnerable or safe enough to be used in a Live production environment. If not, what I can do to be able to use it live? Thank you all in advance.

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• twitter4j code doent work on ICS and JellyBean help me

  - by swapnil adsure

  Hey guys i am using twitter4J to post tweet on twitter Here i Change the Code according to your suggestion . i do some google search. The problem is When i try to shift from main activity to twitter activity it show force close. Main activity is = "MainActivity" twitter activity is = "twiti_backup" I think there is problem in Manifestfile but i dont know what was it. public class twiti_backup extends Activity { private static final String TAG = "Blundell.TweetToTwitterActivity"; private static final String PREF_ACCESS_TOKEN = ""; private static final String PREF_ACCESS_TOKEN_SECRET = ""; private static final String CONSUMER_KEY = ""; private static final String CONSUMER_SECRET = ""; private static final String CALLBACK_URL = "android:///"; private SharedPreferences mPrefs; private Twitter mTwitter; private RequestToken mReqToken; private Button mLoginButton; private Button mTweetButton; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.i(TAG, "Loading TweetToTwitterActivity"); setContentView(R.layout.twite); mPrefs = getSharedPreferences("twitterPrefs", MODE_PRIVATE); mTwitter = new TwitterFactory().getInstance(); mTwitter.setOAuthConsumer(CONSUMER_KEY, CONSUMER_SECRET); mLoginButton = (Button) findViewById(R.id.login_button); mTweetButton = (Button) findViewById(R.id.tweet_button); } public void buttonLogin(View v) { Log.i(TAG, "Login Pressed"); if (mPrefs.contains(PREF_ACCESS_TOKEN)) { Log.i(TAG, "Repeat User"); loginAuthorisedUser(); } else { Log.i(TAG, "New User"); loginNewUser(); } } public void buttonTweet(View v) { Log.i(TAG, "Tweet Pressed"); tweetMessage(); } private void loginNewUser() { try { Log.i(TAG, "Request App Authentication"); mReqToken = mTwitter.getOAuthRequestToken(CALLBACK_URL); Log.i(TAG, "Starting Webview to login to twitter"); WebView twitterSite = new WebView(this); twitterSite.loadUrl(mReqToken.getAuthenticationURL()); setContentView(twitterSite); } catch (TwitterException e) { Toast.makeText(this, "Twitter Login error, try again later", Toast.LENGTH_SHORT).show(); } } private void loginAuthorisedUser() { String token = mPrefs.getString(PREF_ACCESS_TOKEN, null); String secret = mPrefs.getString(PREF_ACCESS_TOKEN_SECRET, null); // Create the twitter access token from the credentials we got previously AccessToken at = new AccessToken(token, secret); mTwitter.setOAuthAccessToken(at); Toast.makeText(this, "Welcome back", Toast.LENGTH_SHORT).show(); enableTweetButton(); } @Override protected void onNewIntent(Intent intent) { super.onNewIntent(intent); Log.i(TAG, "New Intent Arrived"); dealWithTwitterResponse(intent); } @Override protected void onResume() { super.onResume(); Log.i(TAG, "Arrived at onResume"); } private void dealWithTwitterResponse(Intent intent) { Uri uri = intent.getData(); if (uri != null && uri.toString().startsWith(CALLBACK_URL)) { // If the user has just logged in String oauthVerifier = uri.getQueryParameter("oauth_verifier"); authoriseNewUser(oauthVerifier); } } private void authoriseNewUser(String oauthVerifier) { try { AccessToken at = mTwitter.getOAuthAccessToken(mReqToken, oauthVerifier); mTwitter.setOAuthAccessToken(at); saveAccessToken(at); // Set the content view back after we changed to a webview setContentView(R.layout.twite); enableTweetButton(); } catch (TwitterException e) { Toast.makeText(this, "Twitter auth error x01, try again later", Toast.LENGTH_SHORT).show(); } } private void enableTweetButton() { Log.i(TAG, "User logged in - allowing to tweet"); mLoginButton.setEnabled(false); mTweetButton.setEnabled(true); } private void tweetMessage() { try { mTwitter.updateStatus("Test - Tweeting with @Blundell_apps #AndroidDev Tutorial using #Twitter4j http://blog.blundell-apps.com/sending-a-tweet/"); Toast.makeText(this, "Tweet Successful!", Toast.LENGTH_SHORT).show(); } catch (TwitterException e) { Toast.makeText(this, "Tweet error, try again later", Toast.LENGTH_SHORT).show(); } } private void saveAccessToken(AccessToken at) { String token = at.getToken(); String secret = at.getTokenSecret(); Editor editor = mPrefs.edit(); editor.putString(PREF_ACCESS_TOKEN, token); editor.putString(PREF_ACCESS_TOKEN_SECRET, secret); editor.commit(); } } And here is Manifest <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="@string/title_activity_main" android:launchMode="singleInstance" android:configChanges="orientation|screenSize"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".twiti_backup" android:launchMode="singleInstance"> <action android:name="android.intent.action.VIEW" /> <category android:name="android.intent.category.DEFAULT" /> <category android:name="android.intent.category.BROWSABLE" /> <data android:scheme="android" android:host="callback_main" /> </activity> <activity android:name=".MyTwite"/> <activity android:name=".mp3" /> <activity android:name=".myfbapp" /> </application> Here is Log cat when i try to launch twiti_backup from main activity W/dalvikvm(16357): threadid=1: thread exiting with uncaught exception (group=0x4001d5a0) E/AndroidRuntime(16357): FATAL EXCEPTION: main E/AndroidRuntime(16357): java.lang.VerifyError: com.example.uitest.twiti_backup E/AndroidRuntime(16357): at java.lang.Class.newInstanceImpl(Native Method) E/AndroidRuntime(16357): at java.lang.Class.newInstance(Class.java:1409) E/AndroidRuntime(16357): at android.app.Instrumentation.newActivity(Instrumentation.java:1040) E/AndroidRuntime(16357): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1735) E/AndroidRuntime(16357): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1842) E/AndroidRuntime(16357): at android.app.ActivityThread.access$1500(ActivityThread.java:132) E/AndroidRuntime(16357): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1038) E/AndroidRuntime(16357): at android.os.Handler.dispatchMessage(Handler.java:99) E/AndroidRuntime(16357): at android.os.Looper.loop(Looper.java:143) E/AndroidRuntime(16357): at android.app.ActivityThread.main(ActivityThread.java:4263) E/AndroidRuntime(16357): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime(16357): at java.lang.reflect.Method.invoke(Method.java:507) E/AndroidRuntime(16357): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) E/AndroidRuntime(16357): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) E/AndroidRuntime(16357): at dalvik.system.NativeStart.main(Native Method)

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• PHP - My array returns NULL values when placed in a function, but works fine outside of the function

  - by orbit82

  Okay, let me see if I can explain this. I am making a newspaper WordPress theme. The theme pulls posts from categories. The front page shows multiple categories, organized as "newsboxes". Each post should show up only ONCE on the front page, even if said post is in two or more categories. To prevent posts from duplicating on the front page, I've created an array that keeps track of the individual post IDs. When a post FIRST shows up on the front page, its ID gets added to the array. Before looping through the posts for each category, the code first checks the array to see which posts have ALREADY been displayed. OK, so now remember how I said earlier that the front page shows multiple categories organized as "newsboxes"? Well, these newsboxes are called onto the front page using PHP includes. I have 6 newsboxes appearing on the front page, and the code to call them is EXACTLY the same. I didn't want to repeat the same code 6 times, so I put all of the inclusion code into a function. The function works, but the only problem is that it screws up the duplicate posts code I mentioned earlier. The posts all repeat. Running a var_dump on the $do_not_duplicate variable returns an array with null indices. Everything works PERFECTLY if I don't put the code inside a function, but once I do put them in a function it's like the arrays aren't even connecting with the posts. Here is the code with the arrays. The key variables in question here include $do_not_duplicate[] = $post-ID, $do_not_duplicate and 'post__not_in' = $do_not_duplicate <?php query_posts('cat='.$settings['cpress_top_story_category'].'&posts_per_page='.$settings['cpress_number_of_top_stories'].'');?> <?php if (have_posts()) : ?> <!--TOP STORY--> <div id="topStory"> <?php while ( have_posts() ) : the_post(); $do_not_duplicate[] = $post->ID; ?> <a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_post_thumbnail('top-story-thumbnail'); ?></a> <h2 class="extraLargeHeadline"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2> <div class="topStory_author"><?php cpress_show_post_author_byline(); ?></div> <div <?php post_class('topStory_entry') ?> id="post-<?php the_ID(); ?>"> <?php if($settings['cpress_excerpt_or_content_top_story_newsbox'] == "content") { the_content(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php } else { the_excerpt(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php }?> </div><!--/topStoryentry--> <div class="topStory_meta"><?php cpress_show_post_meta(); ?></div> <?php endwhile; wp_reset_query(); ?> <?php if(!$settings['cpress_hide_top_story_more_stories']) { ?> <!--More Top Stories--><div id="moreTopStories"> <?php $category_link = get_category_link(''.$settings['cpress_top_story_category'].''); ?> <?php if (have_posts()) : ?> <?php query_posts( array( 'cat' => ''.$settings['cpress_top_story_category'].'', 'posts_per_page' => ''.$settings['cpress_number_of_more_top_stories'].'', 'post__not_in' => $do_not_duplicate ) ); ?> <h4 class="moreStories"> <?php if($settings['cpress_make_top_story_more_stories_link']) { ?> <a href="<?php echo $category_link; ?>" title="<?php echo strip_tags($settings['cpress_top_story_more_stories_text']);?>"><?php echo strip_tags($settings['cpress_top_story_more_stories_text']);?></a><?php } else { echo strip_tags($settings['cpress_top_story_more_stories_text']); } ?> </h4> <ul> <?php while( have_posts() ) : the_post(); $do_not_duplicate[] = $post->ID; ?> <li><h2 class="mediumHeadline"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2> <?php if(!$settings['cpress_hide_more_top_stories_excerpt']) { ?> <div <?php post_class('moreTopStory_postExcerpt') ?> id="post-<?php the_ID(); ?>"><?php if($settings['cpress_excerpt_or_content_top_story_newsbox'] == "content") { the_content(); ?><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php } else { the_excerpt(); ?> <a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><span class="read_more"><?php echo $settings['cpress_more_text']; ?></span></a> <?php }?> </div><?php } ?> <div class="moreTopStory_postMeta"><?php cpress_show_post_meta(); ?></div> </li> <?php endwhile; wp_reset_query(); ?> </ul> <?php endif;?> </div><!--/moreTopStories--> <?php } ?> <?php echo(var_dump($do_not_duplicate)); ?> </div><!--/TOP STORY--> <?php endif; ?> And here is the code that includes the newsboxes onto the front page. This is the code I'm trying to put into a function to avoid duplicating it 6 times on one page. function cpress_show_templatebitsf($tbit_num, $tbit_option) { global $tbit_path; global $shortname; $settings = get_option($shortname.'_options'); //display the templatebits (usually these will be sidebars) for ($i=1; $i<=$tbit_num; $i++) { $tbit = strip_tags($settings[$tbit_option .$i]); if($tbit !="") { include_once(TEMPLATEPATH . $tbit_path. $tbit.'.php'); } //if }//for loop unset($tbit_option); } I hope this makes sense. It's kind of a complex thing to explain but I've tried many things to fix it and have had no luck. I'm stumped. I'm hoping it's just some little thing I'm overlooking because it seems like it shouldn't be such a problem.

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• Visual Studio C++ list iterator not decementable

  - by user69514

  I keep getting an error on visual studio that says list iterator not decrementable: line 256 My program works fine on Linux, but visual studio compiler throws this error. Dammit this is why I hate windows. Why can't the world run on Linux? Anyway, do you see what my problem is? #include <iostream> #include <fstream> #include <sstream> #include <list> using namespace std; int main(){ /** create the list **/ list<int> l; /** create input stream to read file **/ ifstream inputstream("numbers.txt"); /** read the numbers and add them to list **/ if( inputstream.is_open() ){ string line; istringstream instream; while( getline(inputstream, line) ){ instream.clear(); instream.str(line); /** get he five int's **/ int one, two, three, four, five; instream >> one >> two >> three >> four >> five; /** add them to the list **/ l.push_back(one); l.push_back(two); l.push_back(three); l.push_back(four); l.push_back(five); }//end while loop }//end if /** close the stream **/ inputstream.close(); /** display the list **/ cout << "List Read:" << endl; list<int>::iterator i; for( i=l.begin(); i != l.end(); ++i){ cout << *i << " "; } cout << endl << endl; /** now sort the list **/ l.sort(); /** display the list **/ cout << "Sorted List (head to tail):" << endl; for( i=l.begin(); i != l.end(); ++i){ cout << *i << " "; } cout << endl; list<int> lReversed; for(i=l.begin(); i != l.end(); ++i){ lReversed.push_front(*i); } cout << "Sorted List (tail to head):" << endl; for(i=lReversed.begin(); i!=lReversed.end(); ++i){ cout << *i << " "; } cout << endl << endl; /** remove first biggest element and display **/ l.pop_back(); cout << "List after removing first biggest element:" << endl; cout << "Sorted List (head to tail):" << endl; for( i=l.begin(); i != l.end(); ++i){ cout << *i << " "; } cout << endl; cout << "Sorted List (tail to head):" << endl; lReversed.pop_front(); for(i=lReversed.begin(); i!=lReversed.end(); ++i){ cout << *i << " "; } cout << endl << endl; /** remove second biggest element and display **/ l.pop_back(); cout << "List after removing second biggest element:" << endl; cout << "Sorted List (head to tail):" << endl; for( i=l.begin(); i != l.end(); ++i){ cout << *i << " "; } cout << endl; lReversed.pop_front(); cout << "Sorted List (tail to head):" << endl; for(i=lReversed.begin(); i!=lReversed.end(); ++i){ cout << *i << " "; } cout << endl << endl; /** remove third biggest element and display **/ l.pop_back(); cout << "List after removing third biggest element:" << endl; cout << "Sorted List (head to tail):" << endl; for( i=l.begin(); i != l.end(); ++i){ cout << *i << " "; } cout << endl; cout << "Sorted List (tail to head):" << endl; lReversed.pop_front(); for(i=lReversed.begin(); i!=lReversed.end(); ++i){ cout << *i << " "; } cout << endl << endl; /** create frequency table **/ const int biggest = 1000; //create array size of biggest element int arr[biggest]; //set everything to zero for(int j=0; j<biggest+1; j++){ arr[j] = 0; } //now update number of occurences for( i=l.begin(); i != l.end(); i++){ arr[*i]++; } //now print the frequency table. only print where occurences greater than zero cout << "Final list frequency table: " << endl; for(int j=0; j<biggest+1; j++){ if( arr[j] > 0 ){ cout << j << ": " << arr[j] << " occurences" << endl; } } return 0; }//end main

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