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  • Android ScrollView Not Scrolling Correctly

    - by user3133534
    I've been making my way through thenewboston's android tutorials and I'm stuck on number 35. There is supposed to be a scroll bar that takes up a weight of 30 at the top of the app. There are 6 textview/edittext field groups in the code, but I deleted 5 for simplicity. My problem is that all of the text and text boxes appear on the page and are not confined to the given weight (they all just show up on the page). Has anyone else had this problem or know how to fix it? Please, I'm new to stackoverflow. If you think this is a stupid question, please explain to me why and how I can ask it better. Here is what it looks like: http://imgur.com/gJmOgqk <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:weightSum="100" > <ScrollView android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="30" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" > <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="TextView" /> <EditText android:id="@+id/editText1" android:layout_width="match_parent" android:layout_height="wrap_content" android:ems="10" > </EditText> </LinearLayout> </ScrollView> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="40" android:orientation="vertical" > <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="30" android:orientation="vertical" > <AnalogClock android:id="@+id/analogClock1" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> </LinearLayout>

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  • How to correctly calculate FPS in XNA?

    - by Tomek Tarczynski
    I wrote a component to display current FPS. The most important part of it is: public override void Update(GameTime gameTime) { elapseTime += (float)gameTime.ElapsedRealTime.TotalSeconds; frameCounter++; if (elapseTime > 1) { FPS = frameCounter; frameCounter = 0; elapseTime = 0; } base.Update(gameTime); } In most cases it works ok, but recently I had a problem. When I put following code into Update method of game strange thing starts to happen. if (threadPath == null || threadPath.ThreadState != ThreadState.Running) { ThreadStart ts = new ThreadStart(current.PathFinder.FindPaths); threadPath = new Thread(ts); threadPath.Priority = ThreadPriority.Highest; threadPath.Start(); } Main idea of this code is to run pathFinding algorithm in different thread all the time. By strange things I mean that sometimes FPS drasticly decreases, this is obvious, but displayed FPS changes more often than once a second. If I understand this code FPS can't change more often than once a second. Can someone explain me what's going on?

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  • Code Golf: Collatz Conjecture

    - by Earlz
    Inspired by http://xkcd.com/710/ here is a code golf for it. The Challenge Given a positive integer greater than 0, print out the hailstone sequence for that number. The Hailstone Sequence See Wikipedia for more detail.. If the number is even, divide it by two. If the number is odd, triple it and add one. Repeat this with the number produced until it reaches 1. (if it continues after 1, it will go in an infinite loop of 1 -> 4 -> 2 -> 1...) Sometimes code is the best way to explain, so here is some from Wikipedia function collatz(n) show n if n > 1 if n is odd call collatz(3n + 1) else call collatz(n / 2) This code works, but I am adding on an extra challenge. The program must not be vulnerable to stack overflows. So it must either use iteration or tail recursion. Also, bonus points for if it can calculate big numbers and the language does not already have it implemented. (or if you reimplement big number support using fixed-length integers) Test case Number: 21 Results: 21 -> 64 -> 32 -> 16 -> 8 -> 4 -> 2 -> 1 Number: 3 Results: 3 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1 Also, the code golf must include full user input and output.

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  • How to solve "java.io.IOException: error=12, Cannot allocate memory" calling Runtime#exec()?

    - by Andrea Francia
    On my system I can't run a simple Java application that start a process. I don't know how to solve. Could you give me some hints how to solve? The program is: [root@newton sisma-acquirer]# cat prova.java import java.io.IOException; public class prova { public static void main(String[] args) throws IOException { Runtime.getRuntime().exec("ls"); } } The result is: [root@newton sisma-acquirer]# javac prova.java && java -cp . prova Exception in thread "main" java.io.IOException: Cannot run program "ls": java.io.IOException: error=12, Cannot allocate memory at java.lang.ProcessBuilder.start(ProcessBuilder.java:474) at java.lang.Runtime.exec(Runtime.java:610) at java.lang.Runtime.exec(Runtime.java:448) at java.lang.Runtime.exec(Runtime.java:345) at prova.main(prova.java:6) Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory at java.lang.UNIXProcess.<init>(UNIXProcess.java:164) at java.lang.ProcessImpl.start(ProcessImpl.java:81) at java.lang.ProcessBuilder.start(ProcessBuilder.java:467) ... 4 more Configuration of the system: [root@newton sisma-acquirer]# java -version java version "1.6.0_0" OpenJDK Runtime Environment (IcedTea6 1.5) (fedora-18.b16.fc10-i386) OpenJDK Client VM (build 14.0-b15, mixed mode) [root@newton sisma-acquirer]# cat /etc/fedora-release Fedora release 10 (Cambridge) EDIT: Solution This solves my problem, I don't know exactly why: echo 0 /proc/sys/vm/overcommit_memory Up-votes for who is able to explain :) Additional informations, top output: top - 13:35:38 up 40 min, 2 users, load average: 0.43, 0.19, 0.12 Tasks: 129 total, 1 running, 128 sleeping, 0 stopped, 0 zombie Cpu(s): 1.5%us, 0.5%sy, 0.0%ni, 94.8%id, 3.2%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1033456k total, 587672k used, 445784k free, 51672k buffers Swap: 2031608k total, 0k used, 2031608k free, 188108k cached Additional informations, free output: [root@newton sisma-acquirer]# free total used free shared buffers cached Mem: 1033456 588548 444908 0 51704 188292 -/+ buffers/cache: 348552 684904 Swap: 2031608 0 2031608

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  • google maps api v3 - loop through overlays - overlayview methods

    - by user317005
    what's wrong with the code below? when i execute it, the map doesn't even show up. but when i put the overlayview methods outside the for-loop and manually assign a lat/lng then it magically works?! but does anyone know how i can loop through an array of lats/lngs (=items) using the overlayview methods? i hope this makes sense, just don't know how else to explain it. and unfortunately, i run my code on my localhost var overlay; OverlayTest.prototype = new google.maps.OverlayView(); [taken out: options] var map = new google.maps.Map(document.getElementById('map_canvas'), options); var items = [ ['lat','lng'],['lat','lng'] ]; for (var i = 0; i < items.length; i++) { var latlng = new google.maps.LatLng(items[i][0], items[i][1]); var bounds = new google.maps.LatLngBounds(latlng); overlay = new OverlayTest(map, bounds); function OverlayTest(map, bounds) { [taken out: not important] this.setMap(map); } OverlayTest.prototype.onAdd = function() { [taken out: not important] } OverlayTest.prototype.draw = function() { [taken out: not important] } }

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  • WCF Service Exception

    - by Maciek
    Hiya, I'm currently working on an Silverlight 3 project, I'm using 2 machines to test it. "harbinger" is the web server running Win7 + IIS . I've deployed the webpage and the WCF webservice to that machine. I've entered the following url's in my browser : http://harbinger:43011/UserService.svc http://harbinger:43011/UserService.svc?wsdl and got pages load expected contents for both Next I've decided to check if I can call the webservice from my machine, I've added the ServiceReference, executed a call to one of the methods and .... BOOM : System.ServiceModel.CommunicationException was unhandled by user code Message="An error occurred while trying to make a request to URI 'http://harbinger:43011/UserService.svc'. This could be due to attempting to access a service in a cross-domain way without a proper cross-domain policy in place, or a policy that is unsuitable for SOAP services. You may need to contact the owner of the service to publish a cross-domain policy file and to ensure it allows SOAP-related HTTP headers to be sent. This error may also be caused by using internal types in the web service proxy without using the InternalsVisibleToAttribute attribute. Please see the inner exception for more details." StackTrace: at System.ServiceModel.AsyncResult.End[TAsyncResult](IAsyncResult result) at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.End(SendAsyncResult result) at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result) at System.ServiceModel.ClientBase`1.ChannelBase`1.EndInvoke(String methodName, Object[] args, IAsyncResult result) at Energy.USR.UserServiceClient.UserServiceClientChannel.EndGetAllUsers(IAsyncResult result) at Energy.USR.UserServiceClient.Energy.USR.UserService.EndGetAllUsers(IAsyncResult result) at Energy.USR.UserServiceClient.OnEndGetAllUsers(IAsyncResult result) at System.ServiceModel.ClientBase`1.OnAsyncCallCompleted(IAsyncResult result) InnerException: System.Security.SecurityException Message="" StackTrace: at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state) at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult) at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse(IAsyncResult result) InnerException: System.Security.SecurityException Message="Security error." StackTrace: at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult) at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState) at System.Net.Browser.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState) InnerException: Can someone explain what just happened? What do I need to do to avoid this?

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  • Bluetooth development on Windows mobile 6 C#

    - by cheesebunz
    Hi everyone, i recently started on a project which is a puzzle slider game. This application will be using the Bluetooth, and i'm working on the mobile,Samsung omnia i900. This is how my application will work. Any user with this Samsung device plays the game and starts sliding the tiles. There is an option to search and connect to other users with the same device and application, so that they can solve the puzzle together. Right now, i'm working on the Bluetooth Part but am still new to the API. I'm using the 32feet.NET inthehandpersonal.net class library while encountering much difficulties. I am able to search for devices by using: private void btnSearch_Click(object sender, EventArgs e) { BluetoothRadio.PrimaryRadio.Mode = RadioMode.Discoverable; BluetoothRadio myRadio = BluetoothRadio.PrimaryRadio; lblSearch.Text = "" + myRadio.LocalAddress.ToString(); bluetoothClient = new BluetoothClient(); Cursor.Current = Cursors.WaitCursor; BluetoothDeviceInfo[] bluetoothDeviceInfo = { }; bluetoothDeviceInfo = bluetoothClient.DiscoverDevices(10); comboBox1.DataSource = bluetoothDeviceInfo; comboBox1.DisplayMember = "DeviceName"; comboBox1.ValueMember = "DeviceAddress"; comboBox1.Focus(); Cursor.Current = Cursors.Default; } Well, to be honest this is a rip off from some sources i found on the internet but i do understand this part. Next i went on to trying to sending a simple "testing.txt" file and i'm stucked at it. I think i will be using something like the OBEX and Obexwebrequest, obexwebresponse, Uri etc. Could anyone explain it in simple terms for me so that i could understand what they are so that i could continue pairing and etc on Bluetooth development. Sorry making it this long, really appreciate if anyone did waste some time reading it :). Hope alanM sees this :) i'm using their bluetooth library.

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  • Weird RecordStore behavior when RecordStoreFullException occurs

    - by Michael P
    Hello everyone! I'm developing a small J2ME application that displays bus stops timetables - they are stored as records in MIDP RecordStores. Sometimes records can not fit a single RecordStore, especially on record update - using setRecord method - a RecordStoreFullException occurs. I catch the exception, and try to write the record to a new RecordStore along with deleting the previous one in the old RecordStore. Everything works fine except of deleting record from RecordStore where the RecordStoreFullException occurs. If I make an attempt to delete record that could not be updated, another Exception of type InvalidRecordIDException is thrown. This is weird and undocumented in MIDP javadoc. I have tested it on Sun WTK 2.5.2, MicroEdition SDK 3.0 and Nokia Series 40 SDK. Furthermore I created a code that reproduces this strange behaviour: RecordStore rms = null; int id = 0; try { rms = RecordStore.openRecordStore("Test", true); byte[] raw = new byte[192*10024]; //Big enough to cause RecordStoreFullException id = rms.addRecord(raw, 0, 160); rms.setRecord(id, raw, 0, raw.length); } catch (Exception e) { try { int count = rms.getNumRecords(); RecordEnumeration en = rms.enumerateRecords(null, null, true); count = en.numRecords(); while(en.hasNextElement()){ System.out.println("NextID: "+en.nextRecordId()); } rms.deleteRecord(id); //this won't work! rms.setRecord(id, new byte[5], 0, 5); //this won't work too! } catch (Exception ex) { ex.printStackTrace(); } } I added extra enumeration code to produce other weird behavior - when RecordStoreFullException occurs, count variable will be set to 1 (if RMS was empty) by both methods - getNumRecords and numRecords. System.out.println will produce NextID: 0! It is not acceptable because record ID can not be 0! Could someone explain this strange behavior? Sorry for my bad English.

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  • Why is software quality so problematic?

    - by Yuval A
    Even when viewing the subject in the most objective way possible, it is clear that software, as a product, generally suffers from low quality. Take for example a house built from scratch. Usually, the house will function as it is supposed to. It will stand for many years to come, the roof will support heavy weather conditions, the doors and the windows will do their job, the foundations will not collapse even when the house is fully populated. Sure, minor problemsdo occur, like a leaking faucet or a bad paint job, but these are not critical. Software, on the other hand is much more susceptible to suffer from bad quality: unexpected crashes, erroneous behavior, miscellaneous bugs, etc. Sure, there are many software projects and products which show high quality and are very reliable. But lots of software products do not fall in this category. Take into consideration paradigms like TDD which its popularity is on the rise in the past few years. Why is this? Why do people have to fear that their software will not work or crash? (Do you walk into a house fearing its foundations will collapse?) Why is software - subjectively - so full of bugs? Possible reasons: Modern software engineering exists for only a few decades, a small time period compared to other forms of engineering/production. Software is very complicated with layers upon layers of complexity, integrating them all is not trivial. Software development is relatively easy to start with, anyone can write a simple program on his PC, which leads to amateur software leaking into the market. Tight budgets and timeframes do not allow complete and high quality development and extensive testing. How do you explain this issue, and do you see software quality advancing in the near future?

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  • comparison between string literal

    - by wiso
    This very simple code: #include <iostream> using namespace std; void exec(char* option) { cout << "option is " << option << endl; if (option == "foo") cout << "option foo"; else if (option == "bar") cout << "opzion bar"; else cout << "???"; cout << endl; } int main() { char opt[] = "foo"; exec(opt); return 0; } generate two warning: comparison with string literal results in unspecified behaviour. Can you explain why exactly this code doesn't work, but if I change char opt[] to char *opt it works, but generates the warning? Is it related to the \0 termination? What is the difference between the two declaration of opt? What if I use const qualifier? The solution is to use std::string?

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  • Entity Framework, Foreign Keys and EntityKeys

    - by Greg
    I've got a problem with the Entity Framework and the ForeignKeys. I've got a table "BC_Message_Assets" which has 3 FK's (MessageId, AssetId and StatusId). I create my "MessageAsset" like this MessageAsset messageAsset = new MessageAsset(); messageAsset.MessageStatusReference.EntityKey = new EntityKey("MyEntities.MessageStatusSet", "Id", 1); messageAsset.AssetReference.EntityKey = new EntityKey("MyEntities.AssetSet", "Id", 1); messageAsset.MessageReference.EntityKey = new EntityKey("MyEntities.MessageSet", "Id", messageId); context.AddToMessageAssetSet(messageAsset); context.SaveChanges(); But I got the following exception : The INSERT statement conflicted with the FOREIGN KEY constraint \"FK_BC_Message_Assets_BC_Assets\". The conflict occurred in database \"Test\", table \"dbo.BC_Assets\", column 'Id'.\r\nThe statement has been terminated. When I look at the query, I notice that the parameter value for AssetId is "0" despite that I provided "1" to the EntityKey. Here's the generated query : exec sp_executesql N'insert [dbo].[BC_Message_Assets]([MessageId], [AssetId], [CompletionTime], [StatusId]) values (@0, @1, null, @2) ',N'@0 int,@1 int,@2 int',@0=47,@1=0,@2=1 I can't explain what happens. I hardcoded "1" in the EntityKey and I received "0" in the query ?

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  • ValidationException class version mismatch

    - by suszterpatt
    I have a simple EJB application that I can deploy and test on a local WebLogic instance (v10.3.0.0) without problems. I need to deploy this on a remote WL server (v10.3.3.0), and test it from a local machine. Deployment is successful, but when I try to run any of the clients from JDeveloper, I get this error: <2010.06.02. 16:08:36 CEST> <Error> <RJVM> <BEA-000503> <Incoming message header or abbreviation processing failed java.io.InvalidClassException: org.eclipse.persistence.exceptions.ValidationException; local class incompatible: stream classdesc serialVersionUID = 3793659634176227230, local class serialVersionUID = -7605463488982202416 java.io.InvalidClassException: org.eclipse.persistence.exceptions.ValidationException; local class incompatible: stream classdesc serialVersionUID = 3793659634176227230, local class serialVersionUID = -7605463488982202416 at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:562) at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1583) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1316) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at weblogic.rjvm.ClassTableEntry.readExternal(ClassTableEntry.java:36) at java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1792) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1751) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at weblogic.rjvm.InboundMsgAbbrev.readObject(InboundMsgAbbrev.java:65) at weblogic.rjvm.InboundMsgAbbrev.read(InboundMsgAbbrev.java:37) at weblogic.rjvm.MsgAbbrevJVMConnection.readMsgAbbrevs(MsgAbbrevJVMConnection.java:227) at weblogic.rjvm.MsgAbbrevInputStream.init(MsgAbbrevInputStream.java:173) at weblogic.rjvm.MsgAbbrevJVMConnection.dispatch(MsgAbbrevJVMConnection.java:439) at weblogic.rjvm.t3.MuxableSocketT3.dispatch(MuxableSocketT3.java:322) at weblogic.socket.AbstractMuxableSocket.dispatch(AbstractMuxableSocket.java:394) at weblogic.socket.SocketMuxer.readReadySocketOnce(SocketMuxer.java:917) at weblogic.socket.SocketMuxer.readReadySocket(SocketMuxer.java:849) at weblogic.socket.JavaSocketMuxer.processSockets(JavaSocketMuxer.java:283) at weblogic.socket.SocketReaderRequest.run(SocketReaderRequest.java:29) at weblogic.work.ExecuteRequestAdapter.execute(ExecuteRequestAdapter.java:21) at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:145) at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:117) Can anyone explain why I'm getting this error, and what I can do to resolve it?

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  • Click in a ListView item changes status of elements inside the item?

    - by Antonio
    Hi, I don't know exactly how to explain this problem, but I'll try. I have a ListView with several items. Each item has inside a TextView and two ImageView. I want the ImageView change when I click on them, and I want to open a context menu when I press for a long time into the ListView item. For the ImageView, everything works properly. For the whole item, I can show the context menu after a long press, but my problem is that the ImageView changes as well when I am pressing the TextView, for example. Somo pieces of my code: ListView item: <TextView android:id="@+id/title" android:textColor="@color/black" android:maxLines="2" android:textSize="14dip" /> <ImageView android:id="@+id/minus" android:src="@drawable/minusbutton" android:adjustViewBounds="true" android:gravity="center" /> <ImageView android:id="@+id/plus" android:src="@drawable/plusbutton" android:adjustViewBounds="true" android:gravity="center" /> Drawable to change the status of the plus button: <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_enabled="false" android:drawable="@drawable/button_add_normal_disabled" /> <item android:state_enabled="true" android:state_pressed="true" android:drawable="@drawable/button_add_pressed" /> <item android:state_enabled="true" android:state_focused="true" android:state_pressed="false" android:drawable="@drawable/button_add_active" /> <item android:state_enabled="true" android:state_focused="false" android:state_pressed="false" android:drawable="@drawable/button_add_normal" /> I hope you understand my problem. I think that all the children of a view are affected by an event in the parent, but I am not sure. Do you have a solution? Thanks in advance

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  • CGContextSetShadow() - shadow direction reversed between iOS 3.0 and 4.0?

    - by Pascal
    I've been using CGContextSetShadowWithColor() in my Quartz drawing code on the iPhone to generate the "stomped in" look for text and other things (in drawRect: and drawLayer:inContext:). Worked perfectly, but when running the exact same code against iOS 3.2 and now iOS 4.0 I noticed that the shadows are all in the opposite direction. E.g. in the following code I set a black shadow to be 1 pixel above the text, which gave it a "pressed in" look, and now this shadow is 1px below the text, giving it a standard shadow. ... CGContextSetShadowWithColor(context, CGSizeMake(0.f, 1.f), 0.5f, shadowColor); CGContextShowGlyphsAtPoint(context, origin.x, origin.y, glyphs, length); ... Now I don't know whether I am (or have been) doing something wrong or whether there has been a change to the handling of this setting. I haven't applied any transformation that would explain this to me, at least not knowingly. I've flipped the text matrix in one instance, but not in others and this behavior is consistent. Plus I wasn't able to find anything about this in the SDK Release Notes, so it looks like it's probably me. What might be the issue?

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  • Obj-C component-based game architecture and message forwarding

    - by WanderWeird
    Hello, I've been trying to implement a simple component-based game object architecture using Objective-C, much along the lines of the article 'Evolve Your Hierarchy' by Mick West. To this end, I've successfully used a some ideas as outlined in the article 'Objective-C Message Forwarding' by Mike Ash, that is to say using the -(id)forwardingTargetForSelector: method. The basic setup is I have a container GameObject class, that contains three instances of component classes as instance variables: GCPositioning, GCRigidBody, and GCRendering. The -(id)forwardingTargetForSelector: method returns whichever component will respond to the relevant selector, determined using the -(BOOL)respondsToSelector: method. All this, in a way, works like a charm: I can call a method on the GameObject instance of which the implementation is found in one of the components, and it works. Of course, the problem is that the compiler gives 'may not respond to ...' warnings for each call. Now, my question is, how do I avoid this? And specifically regarding the fact that the point is that each instance of GameObject will have a different set of components? Maybe a way to register methods with the container objects, on a object per object basis? Such as, can I create some kind of -(void)registerMethodWithGameObject: method, and how would I do that? Now, it may or may not be obvious that I'm fairly new to Cocoa and Objective-C, and just horsing around, basically, and this whole thing may be very alien here. Of course, though I would very much like to know of a solution to my specific issue, anyone who would care to explain a more elegant way of doing this would additionally be very welcome. Much appreciated, -Bastiaan

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  • Help me understand these generic method warnings

    - by Raj
    Folks, I have a base class, say: public class BaseType { private String id; ... } and then three subclasses: public class TypeA extends BaseType { ... } public class TypeB extends BaseType { ... } public class TypeC extends BaseType { ... } I have a container class that maintains lists of objects of these types: public class Container { private List<TypeA> aList; private List<TypeB> bList; private List<TypeC> cList; // finder method goes here } And now I want to add a finder method to container that will find an object from one of the lists. The finder method is written as follows: public <T extends BaseType> T find( String id, Class<T> clazz ) { final List<T> collection; if( clazz == TypeA.class ) { collection = (List<T>)aList; } else if( clazz == TypeB.class ) { collection = (List<T>)bList; } else if( clazz == TypeC.class ) { collection = (List<T>)cList; } else return null; for( final BaseType value : collection ) { if( value.getId().equals( id ) ) { return (T)value; } } return null; } My question is this: If I don't add all the casts to T in my finder above, I get compile errors. I think the compile should be able to infer the types based on parametrization of the generic method (). Can anyone explain this? Thanks. -Raj

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  • Rails App hangs after few requests

    - by Paddy
    I have Bitnami Rails stack installed on my Mac. To better explain my problem i created a simple scaffold based rails app with mysql as the backend. I can get to perform simple POST and GET requests for a while and after a few requests the app just hangs indefinitely. No exception caught or anything worthwhile in the development log to report this strange behavior. This is the last bit from the development log before the app froze: Processing WritedatasController#index (for 127.0.0.1 at 2010-03-30 20:38:51) [GET] [4;36;1mWritedata Load (0.7ms) [0m [0;1mSELECT * FROM `writedatas` [0m Rendering template within layouts/application Rendering writedatas/index [4;35;1mWritedata Columns (2.9ms) [0m [0mSHOW FIELDS FROM `writedatas` [0m Completed in 99ms (View: 88, DB: 4) | 200 OK [http://localhost/writedatas] [4;36;1mSQL (0.2ms) [0m [0;1mSET NAMES 'utf8' [0m [4;35;1mSQL (0.1ms) [0m [0mSET SQL_AUTO_IS_NULL=0 [0m Processing WritedatasController#new (for 127.0.0.1 at 2010-03-30 20:38:52) [GET] [4;36;1mWritedata Columns (2.0ms) [0m [0;1mSHOW FIELDS FROM `writedatas` [0m Rendering template within layouts/application Rendering writedatas/new Rendered writedatas/_form (5.9ms) Completed in 34ms (View: 25, DB: 2) | 200 OK [http://localhost/writedatas/new] [4;36;1mSQL (0.4ms) [0m [0;1mSET NAMES 'utf8' [0m [4;35;1mSQL (0.1ms) [0m [0mSET SQL_AUTO_IS_NULL=0 [0m Processing WritedatasController#index (for 127.0.0.1 at 2010-03-30 20:39:17) [GET] [4;36;1mWritedata Load (0.7ms) [0m [0;1mSELECT * FROM `writedatas` [0m Rendering template within layouts/application Rendering writedatas/index [4;35;1mWritedata Columns (2.6ms) [0m [0mSHOW FIELDS FROM `writedatas` [0m Completed in 101ms (View: 90, DB: 4) | 200 OK [http://localhost/writedatas] It just hung at this point. And after this happens i have to restart the server, for it to hang again after few requests. This is the weirdest problem i have faced and i am truly stumped.

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  • Why use short-circuit code?

    - by Tim Lytle
    Related Questions: Benefits of using short-circuit evaluation, Why would a language NOT use Short-circuit evaluation?, Can someone explain this line of code please? (Logic & Assignment operators) There are questions about the benefits of a language using short-circuit code, but I'm wondering what are the benefits for a programmer? Is it just that it can make code a little more concise? Or are there performance reasons? I'm not asking about situations where two entities need to be evaluated anyway, for example: if($user->auth() AND $model->valid()){ $model->save(); } To me the reasoning there is clear - since both need to be true, you can skip the more costly model validation if the user can't save the data. This also has a (to me) obvious purpose: if(is_string($userid) AND strlen($userid) > 10){ //do something }; Because it wouldn't be wise to call strlen() with a non-string value. What I'm wondering about is the use of short-circuit code when it doesn't effect any other statements. For example, from the Zend Application default index page: defined('APPLICATION_PATH') || define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); This could have been: if(!defined('APPLICATION_PATH')){ define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); } Or even as a single statement: if(!defined('APPLICATION_PATH')) define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); So why use the short-circuit code? Just for the 'coolness' factor of using logic operators in place of control structures? To consolidate nested if statements? Because it's faster?

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  • Tips on creating user interfaces and optimizing the user experience

    - by Saif Bechan
    I am currently working on a project where a lot of user interaction is going to take place. There is also a commercial side as people can buy certain items and services. In my opinion a good blend of user interface, speed and security is essential for these types of websites. It is fairly easy to use ajax and JavaScript nowadays to do almost everything, as there are a lot of libraries available such as jQuery and others. But this can have some performance and incompatibility issues. This can lead to users just going to the next website. The overall look of the website is important too. Where to place certain buttons, where to place certain types of articles such as faq and support. Where and how to display error messages so that the user sees them but are not bothering him. And an overall color scheme is important too. The basic question is: How to create an interface that triggers a user to buy/use your services I know psychology also plays a huge role in how users interact with your website. The color scheme for example is important. When the colors are irritating on a website you just want to click away. I have not found any articles that explain those concept. Does anyone have any tips and/or recourses where i can get some articles that guide you in making the correct choices for your website.

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  • CallContext and ApplicationHost

    - by p2u
    I tried to create an ApplicationHost. But I had errors like SerializationException and FileNotFoundException. Then I found this blog entry, where it's seem to be a remoting problem. In my little application I use the CallContext, so I tried some approaches. When I empty the CallContext before I create the ApplicationHost, it works: Programm class: namespace ApplicationHostDemo { public class Program { public static void Main(string[] args) { Evil evil = new Evil(); CallContext.SetData(Evil.CALLCONTEXT, evil); CallContext.FreeNamedDataSlot(Evil.CALLCONTEXT); Console.WriteLine("Simple Host-Demo\r\n"); Host host = CreateHost(); CallContext.SetData(Evil.CALLCONTEXT, evil); host.ProcessRequest("Index.aspx"); Console.WriteLine("\r\n\r\nSimple Host-Demo end"); Console.ReadLine(); } public static Host CreateHost() { return (Host)ApplicationHost.CreateApplicationHost(typeof(Host), "/", Directory.GetCurrentDirectory()); } public class Host : MarshalByRefObject { public void ProcessRequest(string page) { SimpleWorkerRequest swr = new SimpleWorkerRequest(page, "", Console.Out); HttpRuntime.ProcessRequest(swr); } } } } Evil class: namespace ApplicationHostDemo { [Serializable] public class Evil : ILogicalThreadAffinative { public const string CALLCONTEXT = "evil"; public string Name { get; set; } } } Do you know or could you explain why it works?

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  • Pseudocode help

    - by vatsag
    Hello All I've been banging my head over few hours for realising this particular logic My task is to have a masterlist ListM elements of which shall be list(again) in the form of ListA(type A) and ListB(type B) and ListC(type C)(some generic type). Also the lists A and ListB can contain elements of type C(some generic type). Coming to the preconditions 1. ListA can contain only 50 elements of type 'A', rest of the elements can be of generic type C 2. ListB can contain only 50 elements of type 'B', rest of the elements can be of generic type C 3. Also the lists(ListA or ListB) can take at max of 100 elements. 4. ListC can contain elements of generic type C and can take max of 100 elements For ex: Now, If i have 200 elements of type A and 200 elements of type B and 600 elements of type C then i should be able to get 4 Lists(50 elements in each list) of type...ListA (because each ListA can contain at max of 50 elements of type A only, rem 50 is typeC) 4 Lists(50 elements in each list) of type...ListB (because each ListA can contain at max of 50 elements of type B only, rem 50 is typeC) 2 Lists(50 elements in each list) of type...ListC i shall be glad to explain it again if my explanation is quite confusing. Can anyone suggest a better way for implementing such a requirement in the form of a pseudocode ? Thanks in advance VATSAG

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  • Use XMPP instead of HTTP

    - by pavel
    Hey guys. My friend and I, we are working on iPhone application. This application uses XMPP protocol to provide chat functionality. Right now we are designing architecture for the application. So my friend is working on iPhone side, and I am ruby on rails guy. My friend suggested, that we wrap every call, that is usually served via HTTP into XMPP. So, user registration, users search, profile editing, photo uploading, everything goes via XMPP. No HTTP at all. My friend wants to use XMPP, because he says, that it's much easier to implement XMPP on client-side rather HTTP. As for me, this is bullshit, but we've got a product owner, who have been working with my friend for a long time and he trusts him. So what I'm trying to do is to convince my friend and product owner that using XMPP for what HTTP can work find — is totally not the best idea. I feel, that if we implement everything on XMPP, we will have a pain in an ass till the end of lives. But how do I prove it? P.S. I'm not against chat over XMPP, I am against users search, photo uploading, rankings, nearby search and various other restful requests. Please, leave response. Any help appreciated. A little update: Yesterday we had a long discussion. And it turns out, it's quiete hard to receive response from both XMPP and HTTP in Objective-C. Because every single object and its data should be stored in Core Data model, while this model can't be securely modified from various places. Say, if you use HTTP transport, you always want to use only HTTP transport to update data in your model. And if you use XMPP, you should always use XMPP. So, you can't use both. That's what my iPhone buddy told me. It sounds weird for me, can anyone explain me that?

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  • How did the Lunar Lander example make the image backgrounds transparent?

    - by user279112
    Hello. I'm trying to make a GUI program with the Android SDK, using their Lunar Lander example as a significant self-teaching tool in the process. I've noticed their sprites' images' backgrounds, which were at least usually pure white, did not show up in their program. I want to ask how they did that, since their site doesn't explain simple things very well. I've managed to pull that off before on another GUI SDK, wherein all I had to do was to call a function and pass it a few floats to define a certain color, and until my code told it to do otherwise, that function would make sure that that particular color in my sprites' images was totally transparent. However I've wrestled with the Lunar Lander example and getting my own program to show some custom graphics for a week or two now, and I haven't noticed any such function call in the Lunar Lander example. I tried to look for it, but I did not find anything. I've tried to Google some tutorial or other reference material, but what I've found so far is just straying off into unrelated areas and totally dodging this EXTREMELY important lesson on the SDK's basics. Any ideas? Thanks!

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  • .NET4: In-Process Side-by-Side Execution Explained

    - by emptyset
    Overview: I'm interested in learning more about the .NET4 "In-Process Side-by-Side Execution" of assemblies, and need additional information to help me demystify it. Motivation: The application in question is built against .NET2, and uses two third-party libraries that also work against .NET2. The application is deployed (via file copy) to client machines in a virtual environment that includes .NET2. Not my architecture, please bear with me. Goal: To see if it's possible to rebuild the application assemblies (or a subset) against .NET4, and ship the application as before, without changing the third-party libraries and including the .NET4 Client Profile (as described here) in the deployment. Steps Taken: The following articles were read, but didn't quite provide me enough information: In-Process Side-by-Side Execution: Browsed this article, and Scenario Two is the closest it comes to describing something that resembles my situation, but doesn't really cover it with any depth. ASP.NET Side-by-Side Execution Overview: This article covers a web application, but I'm dealing with a client WinForms application. CLR Team Blog: In-Process Side-by-Side: This is useful to explain how plug-ins to host processes function under .NET4, but I don't know if this applies to the third-party libraries. Further Steps: I'm also unclear on how to proceed upgrading a single .NET2 assembly to .NET4, with the overall application remaining in .NET2 (i.e. how to configure the solution/project files, if any special code needs to be included, etc.).

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  • Indentation annoyance with CSS in Vim

    - by Johan Sahlén
    I've moved from TextMate to Vim lately, and am really liking the switch. However, I have an itch regarding the way Vim handles indentation within curly braces using the CSS syntax. I use simple_pairs.vim, which may or may not have something to do with my problem, but I don't think so, as things work fine in PHP, JavaScript, etc. Let me explain… I generally group my CSS rules by context using indentation, like so: ul#nav { margin: 10px; } ul#nav li { float: left; margin-right: 4px; } That means when I type my ul#nav li rule, followed by { (which inserts a corresponding } automatically) and hit enter, I want the closing brace to be at the same indentation level as the ul#…, but instead I get something like this: ul#nav { margin: 10px; } ul#nav li { } So I have to indent the extra step(s) manually. Like I said, doing the same thing in PHP, JavaScript, etc, works fine. Does anyone know how I can fix this? I don't understand enough of Vim's syntax definition files for me to be able to figure out what in the PHP syntax file makes it work, and port it over to the CSS one… Thanks.

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