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  • junit test error - ClassCastException

    - by Josepth Vodary
    When trying to run a junit test I get the following error - java.lang.ClassCastException: business.Factory cannot be cast to services.itemservice.IItemsService at business.ItemManager.get(ItemManager.java:56) at business.ItemMgrTest.testGet(ItemMgrTest.java:49) The specific test that is causing the problem is @Test public void testGet() { Assert.assertTrue(itemmgr.get(items)); } The code it is testing is... public boolean get(Items item) { boolean gotItems = false; Factory factory = Factory.getInstance(); @SuppressWarnings("static-access") IItemsService getItem = (IItemsService)factory.getInstance(); try { getItem.getItems("pens", 15, "red", "gel"); gotItems = true; } catch (ItemNotFoundException e) { // catch e.printStackTrace(); System.out.println("Error - Item Not Found"); } return gotItems; } The test to store items, which is nearly identical, works just fine... The factory class is.. public class Factory { private Factory() {} private static Factory Factory = new Factory(); public static Factory getInstance() {return Factory;} public static IService getService(String serviceName) throws ServiceLoadException { try { Class<?> c = Class.forName(getImplName(serviceName)); return (IService)c.newInstance(); } catch (Exception e) { throw new ServiceLoadException(serviceName + "not loaded"); } } private static String getImplName (String serviceName) throws Exception { java.util.Properties props = new java.util.Properties(); java.io.FileInputStream fis = new java.io.FileInputStream("config\\application.properties"); props.load(fis); fis.close(); return props.getProperty(serviceName); } }

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  • JAVA - How to code Node neighbours in a Grid ?

    - by ke3pup
    Hi guys I'm new to programming and as a School task i need to implement BFS,DFS and A* search algorithms in java to search for a given Goal from a given start position in a Grid of given size, 4x4,8x8..etc to begin with i don't know how to code the neighbors of all the nodes. For example tile 1 in grid as 2 and 9 as neighbors and Tile 12 has ,141,13,20 as its neighbours but i'm struggling to code that. I need the neighbours part so that i can move from start position to other parts of gird legally by moving horizontally or vertically through the neighbours. my node class is: class node { int value; LinkedList neighbors; bool expanded; } let's say i'm given a 8x8 grid right, So if i start the program with a grid of size 8x8 right : 1 - my main will func will create an arrayList of nodes for example node ArrayList test = new ArrayList(); and then using a for loop assign value to all the nodes in arrayList from 1 to 64 (if the grid size was 8x8). BUT somehow i need t on coding that, if anyone can give me some details i would really appreciate it.

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  • (Java) Is there a type of object that can handle anything from primitives to arrays?

    - by Michael
    I'm pretty new to Java, so I'm hoping one of you guys knows how to do this. I'm having the user specify both the type and value of arguments, in any XML-like way, to be passed to methods that are external to my application. Example: javac myAppsName externalJavaClass methodofExternalClass [parameters] Of course, to find the proper method, we have to have the proper parameter types as the method may be overloaded and that's the only way to tell the difference between the different versions. Parameters are currently formatted in this manner: (type)value(/type), e.g. (int)71(/int) (string)This is my string that I'm passing as a parameter!(/string) I parse them, getting the constructor for whatever type is indicated, then execute that constructor by running its method, newInstance(<String value>), loading the new instance into an Object. This works fine and dandy, but as we all know, some methods take arrays, or even multi-dimensional arrays. I could handle the argument formatting like so: (array)(array)(int)0(/int)(int)1(/int)(/array)(array)(int)2(/int)(int)3(/int)(/array)(/array)... or perhaps even better... {{(int)0(/int)(int)1(/int)}{(int)2(/int)(int)3(/int)}}. The question is, how can this be implemented? Do I have to start wrapping everything in an Object[] array so I can handle primitives, etc. as argObj[0], but load an array as I normally would? (Unfortunately, I would have to make it an Object[][] array if I wanted to support two-dimensional arrays. This implementation wouldn't be very pretty.)

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  • What does this Java generics paradigm do and what is it called?

    - by Tom
    I'm looking at some Java classes that have the following form: public abstract class A <E extends A<E>> implements Comparable <E> { public final int compareTo( E other ) { // etc } } public class B extends A <B> { // etc } public class C extends A <C> { // etc } My usage of "Comparable" here is just to illustrate a possible use of the generic parameter "E". Does this usage of generics/inheritance have a name? What is it used for? My impression is that this allows the abstract class to provide a common implementation of a method (such as compareTo) without having to provide it in the subclasses. However, in this example, unlike an inherited method it would restrict subclasses to invoking compareTo on other instances of the same subclass, rather than any "A" subclass. Does this sound right? Anyway, just curious if any gurus out there have seen this before and know what it does. Thanks!

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  • Why does Java automatically decode %2F in URI encoded filenames?

    - by Lucas
    I have a java servlet that needs to write out files that have a user-configurable name. I am trying to use URI encoding to properly escape special characters, but the JRE appears to automatically convert encoded forward slashes (%2F) into path separators. Example: File dir = new File("C:\Documents and Setting\username\temp"); String fn = "Top 1/2.pdf"; URI uri = new URI( dir.toURI().toASCIIString() + URLEncoder.encoder( fn, "UTF-8" ).toString() ); File out = new File( uri ); System.out.println( dir.toURI().toASCIIString() ); System.out.println( URLEncoder.encoder( fn, "UTF-8" ).toString() ); System.out.println( uri.toASCIIString() ); System.out.println( output.toURI().toASCIIString() ); The output is: file:/C:/Documents%20and%20Settings/username/temp/ Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1/2.pdf After the new File object is instantiated, the %2F sequence is automatically converted to a forward slash and I end up with an incorrect path. Does anybody know the proper way to approach this issue? The core of the problem seems to be that uri.equals( new File(uri).toURI() ) == FALSE when there is a '%2F' in the URI. I'm planning to just use the URLEncoded string verbatim rather than trying to use the File(uri) constructor.

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  • Egy klassz ADF eloadás

    - by peter.nagy
    Túl vagyunk a Technology Forum rendezvényünkön, és én azt gondolom nagyon hasznos volt. Grant nagyszeru eloadást tartott. Címe Forms to ADF: WHy and How. Szerintem maga a demó, ami persze nem letöltheto igazán hasznos volt nem csak Forms háttérrel rendelkezo fejlesztok számára is. Sok rendezvényünkön hintettük az igét ADF-vel kapcsolatban, de átüto penetrációt nem értünk el vele a hazai piacon. Ennek persze több oka is van/lehet. Egyrészrol még mindig azt gondolom (fejlesztoi múltamból fakadóan is), hogy Magyarországon mindenki saját fejlesztésu keretrendszerrel szeret dolgozni. Ezen persze órákat lehet vitatkozni pro és kontra amit akár egy másik bejegyzésben szívesen meg i teszek ha van rá igény. De tény az, hogy már elmúltak azok az idok amikor nem voltak használható keretrendszerek, vagy ha úgy tetszik komponensek. Mégis, megéri manapság lefejleszteni pl: egy üzenetküldo (messaging) alrendszert. Hát szerintem nem, mint ahogy ma már perzisztencia kezelo réteget se állunk neki megírni. Persze ha a projekt elbírja, akkor kifizetodo. Szerencsére egyre több cég ismeri fel és várja el, hogy nem kell neki lefejleszteni egy komplett keretrendszert mikor számos használható van a piacon. Visszatérve az alap kérdésre, az ADF-re azt gondolom, hogy egy fo vissza tartó ero volt a termék érettsége, funkcionalitása és leginkább jövoképe. Nos e tekintetben elismerem, hogy bár több, mint 10 éves múltra tekint vissza korábban voltak buktatók, zsákutcák. Ugyanakkor nem szabad elfelejteni, hogy az Oracle maga ezzel fejleszti új generációs, modern Fusion Appplications (EBusiness Suite, PeopleSoft stb.) alkalmazásait. Tehát több mint ezer(!) fejleszto használja nap, mint nap Java EE alkalmazás fejlesztésére. Nem kevés hangsúlyt fordítva az integrációs, testreszabhatósági képességekre. Olyannyira hangsúlyos eszköz lett, hogy az Oracle teljes middleware portfoliójában visszaköszön. Ami pedig a funkcionalitást, a felhasználói felületet, a produktivitást illeti tényleg jó. Persze az utolsó és egyben legfontosabb szempont kishazánkban az ár. Nos tényleg nincs ingyen. Pontosabban ha az ember vesz egy Weblogic szervert (amúgyis kell a futtatáshoz egy JEE szerver) akkor ingyenesen használható. A termékhez pedig dokumentáció, support, javítás, blogok, közösségi fórumok stb. áll rendelkezésünkre. És akkor most újabb vita indulhat arról, hogy akarunk e fizetni a szerverért. Na errol tényleg fogok indítani egy bejegyzést majd. Mert én azt hiszem, tapasztalatom, hogy itthon összekeverik az open source modelt az ingyenességgel. Azért az alapigazság szerintem még mindig áll: ingyen nincsen semmi. Kérdés csak az, hogy mik az igényeink, elvárásaink.

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  • A* navigational mesh path finding

    - by theguywholikeslinux
    So I've been making this top down 2D java game in this framework called Greenfoot [1] and I've been working on the AI for the guys you are gonna fight. I want them to be able to move around the world realistically so I soon realized, amongst a couple of other things, I would need some kind of pathfinding. I have made two A* prototypes. One is grid based and then I made one that works with waypoints so now I need to work out a way to get from a 2d "map" of the obstacles/buildings to a graph of nodes that I can make a path from. The actual pathfinding seems fine, just my open and closed lists could use a more efficient data structure, but I'll get to that if and when I need to. I intend to use a navigational mesh for all the reasons out lined in this post on ai-blog.net [2]. However, the problem I have faced is that what A* thinks is the shortest path from the polygon centres/edges is not necessarily the shortest path if you travel through any part of the node. To get a better idea you can see the question I asked on stackoverflow [3]. I got a good answer concerning a visibility graph. I have since purchased the book (Computational Geometry: Algorithms and Applications [4]) and read further into the topic, however I am still in favour of a navigational mesh (See "Managing Complexity" [5] from Amit’s Notes about Path-Finding [6]). (As a side note, maybe I could possibly use Theta* to convert multiple waypoints into one straight line if the first and last are not obscured. Or each time I move back check to the waypoint before last to see if I can go straight from that to this) So basically what I want is a navigational mesh where once I have put it through a funnel algorithm (e.g. this one from Digesting Duck [7]) I will get the true shortest path, rather than get one that is the shortest path following node to node only, but not the actual shortest given that you can go through some polygons and skip nodes/edges. Oh and I also want to know how you suggest storing the information concerning the polygons. For the waypoint prototype example I made I just had each node as an object and stored a list of all the other nodes you could travel to from that node, I'm guessing that won't work with polygons? and how to I tell if a polygon is open/traversable or if it is a solid object? How do I store which nodes make up the polygon? Finally, for the record: I do want to programme this by myself from scratch even though there are already other solutions available and I don't intend to be (re) using this code in anything other than this game so it does not matter that it will inevitably be poor quality. http://greenfoot.org http://www.ai-blog.net/archives/000152.html http://stackoverflow.com/q/7585515/ http://www.cs.uu.nl/geobook/ http://theory.stanford.edu/~amitp/GameProgramming/MapRepresentations.html http://theory.stanford.edu/~amitp/GameProgramming/ http://digestingduck.blogspot.com/2010/03/simple-stupid-funnel-algorithm.html

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  • Voice echo in UDP based voice transmission [closed]

    - by Meherzad
    I have coded a java application for voice transmission between to ip in LAN. Here the code. public static Boolean flag= true; public static Boolean recFlag=true; DatagramSocket UDPSocket=null; AudioFormat format = null; TargetDataLine microphone=null; byte[] buffer=null; DatagramPacket UDPPacket=null; public void startChat(String ipAddress){ try{ buffer = new byte[1000]; UDPSocket=new DatagramSocket(1987); Thread th=new Thread(new Listener()); th.start(); microphone = AudioSystem.getTargetDataLine(format); format= new AudioFormat(8000.0f, 16, 1, true, true); UDPPacket = new DatagramPacket(buffer, buffer.length, InetAddress.getByName(ipAddress), 1988); microphone.open(format); microphone.start(); while (flag) { microphone.read(buffer, 0, buffer.length); UDPSocket.send(UDPPacket); } } catch(Exception e){ System.out.println(" ssss "+e.getMessage()); } } public class Listener extends Thread{ byte[] buff=new byte[1000]; DatagramSocket UDPSocket1=null; DatagramPacket recPacket=null; DataLine.Info info = new DataLine.Info(SourceDataLine.class, format); SourceDataLine line=null; @Override public void run(){ try{ UDPSocket1=new DatagramSocket(1988); format= new AudioFormat(8000.0f, 16, 1, true, true); line = (SourceDataLine) AudioSystem.getLine(info); line.open(format); line.start(); } catch(Exception e){ System.out.println("list "+ e.getMessage()); } recPacket=new DatagramPacket(buff, buff.length); while(recFlag){ try{ UDPSocket1.receive(recPacket); buff = (byte[])recPacket.getData(); line.write(buff, 0, buff.length); } catch(Exception e){ System.out.println("errr "+e.getMessage()); } } line.drain(); line.close(); } } Main problem which I am facing that I am getting only echo of my own voice. I am unable to hear voice from the other end only I am hearing is my own voice. Please suggest any solution.

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  • Space partitioning when everything is moving

    - by Roy T.
    Background Together with a friend I'm working on a 2D game that is set in space. To make it as immersive and interactive as possible we want there to be thousands of objects freely floating around, some clustered together, others adrift in empty space. Challenge To unburden the rendering and physics engine we need to implement some sort of spatial partitioning. There are two challenges we have to overcome. The first challenge is that everything is moving so reconstructing/updating the data structure has to be extremely cheap since it will have to be done every frame. The second challenge is the distribution of objects, as said before there might be clusters of objects together and vast bits of empty space and to make it even worse there is no boundary to space. Existing technologies I've looked at existing techniques like BSP-Trees, QuadTrees, kd-Trees and even R-Trees but as far as I can tell these data structures aren't a perfect fit since updating a lot of objects that have moved to other cells is relatively expensive. What I've tried I made the decision that I need a data structure that is more geared toward rapid insertion/update than on giving back the least amount of possible hits given a query. For that purpose I made the cells implicit so each object, given it's position, can calculate in which cell(s) it should be. Then I use a HashMap that maps cell-coordinates to an ArrayList (the contents of the cell). This works fairly well since there is no memory lost on 'empty' cells and its easy to calculate which cells to inspect. However creating all those ArrayLists (worst case N) is expensive and so is growing the HashMap a lot of times (although that is slightly mitigated by giving it a large initial capacity). Problem OK so this works but still isn't very fast. Now I can try to micro-optimize the JAVA code. However I'm not expecting too much of that since the profiler tells me that most time is spent in creating all those objects that I use to store the cells. I'm hoping that there are some other tricks/algorithms out there that make this a lot faster so here is what my ideal data structure looks like: The number one priority is fast updating/reconstructing of the entire data structure Its less important to finely divide the objects into equally sized bins, we can draw a few extra objects and do a few extra collision checks if that means that updating is a little bit faster Memory is not really important (PC game)

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  • How do I draw a scene with 2 nested frames

    - by Guido Granobles
    I have been trying for long time to figure out this: I have loaded a model from a directx file (I am using opengl and Java) the model have a hierarchical system of nested reference frames (there are not bones). There are just 2 frames, one of them is called x3ds_Torso and it has a child frame called x3ds_Arm_01. Each one of them has a mesh. The thing is that I can't draw the arm connected to the body. Sometimes the body is in the center of the screen and the arm is at the top. Sometimes they are both in the center. I know that I have to multiply the matrix transformation of every frame by its parent frame starting from the top to the bottom and after that I have to multiply every vertex of every mesh by its final transformation matrix. So I have this: public void calculeFinalMatrixPosition(Bone boneParent, Bone bone) { System.out.println("-->" + bone.name); if (boneParent != null) { bone.matrixCombined = bone.matrixTransform.multiply(boneParent.matrixCombined); } else { bone.matrixCombined = bone.matrixTransform; } bone.matrixFinal = bone.matrixCombined; for (Bone childBone : bone.boneChilds) { calculeFinalMatrixPosition(bone, childBone); } } Then I have to multiply every vertex of the mesh: public void transformVertex(Bone bone) { for (Iterator<Mesh> iterator = meshes.iterator(); iterator.hasNext();) { Mesh mesh = iterator.next(); if (mesh.boneName.equals(bone.name)) { float[] vertex = new float[4]; double[] newVertex = new double[3]; if (mesh.skinnedVertexBuffer == null) { mesh.skinnedVertexBuffer = new FloatDataBuffer( mesh.numVertices, 3); } mesh.vertexBuffer.buffer.rewind(); while (mesh.vertexBuffer.buffer.hasRemaining()) { vertex[0] = mesh.vertexBuffer.buffer.get(); vertex[1] = mesh.vertexBuffer.buffer.get(); vertex[2] = mesh.vertexBuffer.buffer.get(); vertex[3] = 1; newVertex = bone.matrixFinal.transpose().multiply(vertex); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[0])); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[1])); mesh.skinnedVertexBuffer.buffer.put(((float) newVertex[2])); } mesh.vertexBuffer = new FloatDataBuffer( mesh.numVertices, 3); mesh.skinnedVertexBuffer.buffer.rewind(); mesh.vertexBuffer.buffer.put(mesh.skinnedVertexBuffer.buffer); } } for (Bone childBone : bone.boneChilds) { transformVertex(childBone); } } I know this is not the more efficient code but by now I just want to understand exactly how a hierarchical model is organized and how I can draw it on the screen. Thanks in advance for your help.

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  • Returning null vs Throwing exceptions

    - by Svish
    Is in a bit of disagreement with a more experienced developer on this issue, and was wondering what you guys here think about this. Environment is Java, EJB 3, services, etc. The code I wrote calls a service to get things and to create things. Problem was that I got null pointer exceptions in places that didn't make sense. For example when I asked the service to create an object, I got null back. And when I tried to look up an object with an id I knew existed, I still got null back. Was like it was ignoring me. Spent some time trying to figure out what was wrong in my code (since I'm less experienced I usually assume I have messed up). Turns out the reason was security. If the user principal using my service didn't have the right permissions to use the service I called from my service, then that service simply returned null. The services that are here already are usually not documented either, so this is just something you have to know... somehow... So here is the thing: I mean that this is rather confusing as a developer interacting with this service. To me it would make much more sense if that service thew an exception which would tell me that hey, you don't have the proper permissions to get info about this thing or to create this new thing. I would then immediately know why my service wasn't working as expected. However, he argued that asking is not wrong. Exceptions should only be thrown when there is an error and asking for a thing is not an error. Even if you don't have permission to "see" that the thing you asked for. The things are often looked up in a GUI by users and for those users not having the right permissions, these things simply "do not exist". So, in short: Asking is not wrong, hence no exception. Get methods return null because to those users those things "doesn't exist". Create methods return null because nothing was created, since the user wasn't allowed to create anything. So, what do you guys think? Is this normal and/or good practice? I prefer exceptions as I prefer throwing and catching exceptions because I find it much easier to know what's going on. So I would for example also prefer to throw a NotFoundException if you asked for an id which didn't exist, rather than returning null. Anyways, just curious to what others think about this as I'm not the most experienced developer yet.

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  • MiniMax function throws null pointer exception

    - by Sven
    I'm working on a school project, I have to build a tic tac toe game with the AI based on the MiniMax algorithm. The two player mode works like it should. I followed the code example on http://ethangunderson.com/blog/minimax-algorithm-in-c/. The only thing is that I get a NullPointer Exception when I run the code. And I can't wrap my finger around it. I placed a comment in the code where the exception is thrown. The recursive call is returning a null pointer, what is very strange because it can't.. When I place a breakpoint on the null return with the help of a if statement, then I see that there ARE still 2 to 3 empty places.. I probably overlooking something. Hope someone can tell me what I'm doing wrong. Here is the MiniMax code (the tic tac toe code is not important): /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package MiniMax; import Game.Block; import Game.Board; import java.util.ArrayList; public class MiniMax { public static Place getBestMove(Board gameBoard, Block.TYPE player) { Place bestPlace = null; ArrayList<Place> emptyPlaces = gameBoard.getEmptyPlaces(); Board newBoard; //loop trough all the empty places for(Place emptyPlace : emptyPlaces) { newBoard = gameBoard.clone(); newBoard.setBlock(emptyPlace.getRow(), emptyPlace.getCell(), player); //no game won and still room to move if(newBoard.getWinner() == Block.TYPE.NONE && newBoard.getEmptyPlaces().size() > 0) { //is an node (has children) Place tempPlace = getBestMove(newBoard, invertPlayer(player)); //ERROR is thrown here! tempPlace is null. emptyPlace.setScore(tempPlace.getScore()); } else { //is an leaf if(newBoard.getWinner() == Block.TYPE.NONE) { emptyPlace.setScore(0); } else if(newBoard.getWinner() == Block.TYPE.X) { emptyPlace.setScore(-1); } else if(newBoard.getWinner() == Block.TYPE.O) { emptyPlace.setScore(1); } //if this move is better then our prev move, take it! if((bestPlace == null) || (player == Block.TYPE.X && emptyPlace.getScore() < bestPlace.getScore()) || (player == Block.TYPE.O && emptyPlace.getScore() > bestPlace.getScore())) { bestPlace = emptyPlace; } } } //This should never be null, but it does.. return bestPlace; } private static Block.TYPE invertPlayer(Block.TYPE player) { if(player == Block.TYPE.X) { return Block.TYPE.O; } return Block.TYPE.X; } }

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  • Why does my sprite glitch when moving? [closed]

    - by rphello101
    Using Slick 2D/Java, I'm using the mouse to rotate a sprite and WASD to move it (A and D are used to strafe). I finally got the directional keys and rotation to work in sync, but I'm having problems with sporadic movement. It seems that the move speed is not always set to the value I have it at. Sometimes the sprite with just shoot across the screen. Furthermore, it seems that at 0 degrees, when the left key is pressed, the sprite moves backwards, not to the left. There also seems to be quite a bit of glitching when two keys are pressed, like left and up. Anyone see anything obvious? Here is the rotational code: int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x+sprite.image.getWidth()/2; int pY = sprite.y+sprite.image.getHeight()/2; double mAng; if(mX!=pX){ mAng = Math.toDegrees(Math.atan2(mY - pY, mX - pX)); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=90; else mAng=270; } sprite.angle = mAng; sprite.image.setRotation((float) mAng); Movement code: Input input = gc.getInput(); Vector2f direction = new Vector2f(); Vector2f velocity = new Vector2f(); Vector2f left; Vector2f right; direction.x = (float) Math.cos(Math.toRadians(sprite.angle)); direction.y = (float) Math.sin(Math.toRadians(sprite.angle)); if(direction.length()>0) direction = direction.normalise(); left = new Vector2f(-direction.y, direction.x); right = new Vector2f(direction.y, -direction.x); velocity.x = (float) (direction.x * sprite.moveSpeed); velocity.y = (float) (direction.y * sprite.moveSpeed); if(input.isKeyDown(sprite.up)){ sprite.x += velocity.x*delta; sprite.y += velocity.y*delta; }if (input.isKeyDown(sprite.down)){ sprite.x -= velocity.x*delta; sprite.y -= velocity.y*delta; }if (input.isKeyDown(sprite.left)){ sprite.x += left.x * sprite.moveSpeed * delta; sprite.y += left.y * sprite.moveSpeed * delta; }if (input.isKeyDown(sprite.right)){ sprite.x += right.x * sprite.moveSpeed * delta; sprite.y += right.y * sprite.moveSpeed * delta; }

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  • How to Make Objects Fall Faster in a Physics Simulation

    - by David Dimalanta
    I used the collision physics (i.e. Box2d, Physics Body Editor) and implemented onto the java code. I'm trying to make the fall speed higher according to the examples: It falls slower if light object (i.e. feather). It falls faster depending on the object (i.e. pebble, rock, car). I decided to double its falling speed for more excitement. I tried adding the mass but the speed of falling is constant instead of gaining more speed. check my code that something I put under input processor's touchUp() return method under same roof of the class that implements InputProcessor and Screen: @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { // TODO Touch Up Event if(is_Next_Fruit_Touched) { BodyEditorLoader Fruit_Loader = new BodyEditorLoader(Gdx.files.internal("Shape_Physics/Fruity Physics.json")); Fruit_BD.type = BodyType.DynamicBody; Fruit_BD.position.set(x, y); FixtureDef Fruit_FD = new FixtureDef(); // --> Allows you to make the object's physics. Fruit_FD.density = 1.0f; Fruit_FD.friction = 0.7f; Fruit_FD.restitution = 0.2f; MassData mass = new MassData(); mass.mass = 5f; Fruit_Body[n] = world.createBody(Fruit_BD); Fruit_Body[n].setActive(true); // --> Let your dragon fall. Fruit_Body[n].setMassData(mass); Fruit_Body[n].setGravityScale(1.0f); System.out.println("Eggs... " + n); Fruit_Loader.attachFixture(Fruit_Body[n], Body, Fruit_FD, Fruit_IMG.getWidth()); Fruit_Origin = Fruit_Loader.getOrigin(Body, Fruit_IMG.getWidth()).cpy(); is_Next_Fruit_Touched = false; up = y; Gdx.app.log("Initial Y-coordinate", "Y at " + up); //Once it's touched, the next fruit will set to drag. if(n < 50) { n++; }else{ System.exit(0); } } return true; } And take note, at show() method , the view size from the camera is at 720x1280: camera_1 = new OrthographicCamera(); camera_1.viewportHeight = 1280; camera_1.viewportWidth = 720; camera_1.position.set(camera_1.viewportWidth * 0.5f, camera_1.viewportHeight * 0.5f, 0f); camera_1.update(); I know it's a good idea to add weight to make the falling object falls faster once I released the finger from the touchUp() after I picked the object from the upper right of the screen but the speed remains either constant or slow. How can I solve this? Can you help?

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  • SFX Played Once per Collision or Hit

    - by David Dimalanta
    I have a question about using Box2D (engine for LibGDX used to make realistic physics). I observed on the code that I've made for the physics here below: @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { // TODO Touch Up Event if(is_Next_Fruit_Touched) { BodyEditorLoader Fruit_Loader = new BodyEditorLoader(Gdx.files.internal("Shape_Physics/Fruity Physics.json")); Fruit_BD.type = BodyType.DynamicBody; Fruit_BD.position.set(x, y); FixtureDef Fruit_FD = new FixtureDef(); // --> Allows you to make the object's physics. Fruit_FD.density = 1.0f; Fruit_FD.friction = 0.7f; Fruit_FD.restitution = 0.2f; MassData mass = new MassData(); mass.mass = 5f; Fruit_Body[n] = world.createBody(Fruit_BD); Fruit_Body[n].setActive(true); // --> Let your dragon fall. Fruit_Body[n].setMassData(mass); Fruit_Body[n].setGravityScale(1.0f); System.out.println("Eggs... " + n); Fruit_Loader.attachFixture(Fruit_Body[n], Body, Fruit_FD, Fruit_IMG.getWidth()); Fruit_Origin = Fruit_Loader.getOrigin(Body, Fruit_IMG.getWidth()).cpy(); is_Next_Fruit_Touched = false; up = y; Gdx.app.log("Initial Y-coordinate", "Y at " + up); //Once it's touched, the next fruit will set to drag. if(n < 50) { n++; }else{ System.exit(0); } } return true; } Now, I'm thinking which part o line should I implement for the sound effects. My objectives to make SFX played once for every collision (Or should I say "SFX played once per collision"?) on the following: SFX played once if they hit on the objects of its kind. (e.g. apple vs. apple) SFX played once on a different sound when it hit on the ground. (e.g. apple land on the mud) Take note that I'm using Box2D for the Java programming version thanks to LibGDX via Box2D engine and I edited the physics body using Physics Body Editor before I implement it to code. I tried to check every available methods for body, fixture definition, or body definition to code for the SFX when hit but it seems only for the gravity and weight. Is there possibly available on the document for SFX played when collision happens if possible?

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  • How can I make a universal construction more efficient?

    - by VF1
    A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted wait-free construction, in Java, from [1], which presumes the existence of a wait-free queue that satisfies the interface WFQ (which only requires one-time consensus between threads) and assumes a Sequential interface: public interface WFQ<T> // "FIFO" iteration { int enqueue(T t); // returns the sequence number of t Iterable<T> iterateUntil(int max); // iterates until sequence max } public interface Sequential { // Apply an invocation (method + arguments) // and get a response (return value + state) Response apply(Invocation i); } public interface Factory<T> { T generate(); } // generate new default object public interface Universal extends Sequential {} public class SlowUniversal implements Universal { Factory<? extends Sequential> generator; WFQ<Invocation> wfq = new WFQ<Invocation>(); Universal(Factory<? extends Sequential> g) { generator = g; } public Response apply(Invocation i) { int max = wfq.enqueue(i); Sequential s = generator.generate(); for(Invocation invoc : wfq.iterateUntil(max)) s.apply(invoc); return s.apply(i); } } This implementation isn't very satisfying, however, since it presumes determinism of a Sequential and is really slow. I attempted to add memory recycling: public interface WFQD<T> extends WFQ<T> { T dequeue(int n); } // dequeues only when n is the tail, else assists other threads public interface CopyableSequential extends Sequential { CopyableSequential copy(); } public class RecyclingUniversal implements Universal { WFQD<CopyableSequential> wfqd = new WFQD<CopyableSequential>(); Universal(CopyableSequential init) { wfqd.enqueue(init); } public Response apply(Invocation i) { int max = wfqd.enqueue(i); CopyableSequential cs = null; int ctr = max; for(CopyableSequential csq : wfq.iterateUntil(max)) if(--max == 0) cs = csq.copy(); wfqd.dequeue(max); return cs.apply(i); } } Here are my specific questions regarding the extension: Does my implementation create a linearizable multi-threaded version of a CopyableSequential? Is it possible extend memory recycling without extending the interface (perhaps my new methods trivialize the problem)? My implementation only reduces memory when a thread returns, so can this be strengthened? [1] provided an implementation for WFQ<T>, not WFQD<T> - one does exist, though, correct? [1] Herlihy and Shavit, The Art of Multiprocessor Programming.

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  • Breakout ball collision detection, bouncing against the walls [solved]

    - by Sri Harsha Chilakapati
    I'm currently trying to program a breakout game to distribute it as an example game for my own game engine. http://game-engine-for-java.googlecode.com/ But the problem here is that I can't get the bouncing condition working properly. Here's what I'm using. public void collision(GObject other){ if (other instanceof Bat || other instanceof Block){ bounce(); } else if (other instanceof Stone){ other.destroy(); bounce(); } //Breakout.HIT.play(); } And here's by bounce() method public void bounce(){ boolean left = false; boolean right = false; boolean up = false; boolean down = false; if (dx < 0) { left = true; } else if (dx > 0) { right = true; } if (dy < 0) { up = true; } else if (dy > 0) { down = true; } if (left && up) { dx = -dx; } if (left && down) { dy = -dy; } if (right && up) { dx = -dx; } if (right && down) { dy = -dy; } } The ball bounces the bat and blocks but when the block is on top of the ball, it won't bounce and moves upwards out of the game. What I'm missing? Is there anything to implement? Please help me.. Thanks EDIT: Have changed the bounce method. public void bounce(GObject other){ //System.out.println("y : " + getY() + " other.y + other.height - 2 : " + (other.getY() + other.getHeight() - 2)); if (getX()+getWidth()>other.getX()+2){ setHorizontalDirection(Direction.DIRECTION_RIGHT); } else if (getX()<(other.getX()+other.getWidth()-2)){ setHorizontalDirection(Direction.DIRECTION_LEFT); } if (getY()+getHeight()>other.getY()+2){ setVerticalDirection(Direction.DIRECTION_UP); } else if (getY()<(other.getY()+other.getHeight()-2)){ setVerticalDirection(Direction.DIRECTION_DOWN); } } EDIT: Solved now. See the changed method in my answer.

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  • How to refactor my design, if it seems to require multiple inheritance?

    - by Omega
    Recently I made a question about Java classes implementing methods from two sources (kinda like multiple inheritance). However, it was pointed out that this sort of need may be a sign of a design flaw. Hence, it is probably better to address my current design rather than trying to simulate multiple inheritance. Before tackling the actual problem, some background info about a particular mechanic in this framework: It is a simple game development framework. Several components allocate some memory (like pixel data), and it is necessary to get rid of it as soon as you don't need it. Sprites are an example of this. Anyway, I decided to implement something ala Manual-Reference-Counting from Objective-C. Certain classes, like Sprites, contain an internal counter, which is increased when you call retain(), and decreased on release(). Thus the Resource abstract class was created. Any subclass of this will obtain the retain() and release() implementations for free. When its count hits 0 (nobody is using this class), it will call the destroy() method. The subclass needs only to implement destroy(). This is because I don't want to rely on the Garbage Collector to get rid of unused pixel data. Game objects are all subclasses of the Node class - which is the main construction block, as it provides info such as position, size, rotation, etc. See, two classes are used often in my game. Sprites and Labels. Ah... but wait. Sprites contain pixel data, remember? And as such, they need to extend Resource. But this, of course, can't be done. Sprites ARE nodes, hence they must subclass Node. But heck, they are resources too. Why not making Resource an interface? Because I'd have to re-implement retain() and release(). I am avoiding this in virtue of not writing the same code over and over (remember that there are multiple classes that need this memory-management system). Why not composition? Because I'd still have to implement methods in Sprite (and similar classes) that essentially call the methods of Resource. I'd still be writing the same code over and over! What is your advice in this situation, then?

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  • Draw Cards and Eliminate Cards Problem

    - by Jen
    I am having a problem in this question. I want a system inside a game wherein the player draws 2 cards randomly, and the enemy draws 2 cards randomly. Then, what the program does is to print out to the console the cards the player draw and the enemy's. The cards should not conflict and must not be the same. Then lastly, the program prints out the card that was not drawn by both the player and the enemy. Here's how I did it but it was lengthy and full of errors: import java.util.Random; public class Draw { public static Random random = new Random(); public static String cards[] = {"Hall", "Kitchen", "Billiard", "Study", "Pool"}; public static int playercounter; public static int enemycounter; public static String playercardA = null; public static String playercardB = null; public static String enemycardA = null; public static String enemycardB = null; public String lastcard = null; public static void playercardAdraw() { playercounter = random.nextInt(5); playercardA = cards[playercounter]; } public static void playercardBdraw() { playercounter=random.nextInt(5); playercardB= cards[playercounter]; if (playercardB==playercardA || playercardB == enemycardA || playercardB == enemycardB) { return; } } public static void enemycardAdraw () { enemycounter = random.nextInt(5); enemycardA=cards[enemycounter]; if (enemycardA == playercardA || enemycardA == playercardB) { return; } } public static void enemycardBdraw () { enemycounter = random.nextInt(5); enemycardB=cards[enemycounter]; if (enemycardB == playercardA || enemycardB == playercardB || enemycardB == enemycardA) { return; } } public static void main (String args []) { System.out.println("Starting to draw..."); System.out.println("Player's Turn: "); playercardAdraw(); System.out.println("Player's first card: " + playercardA); playercardBdraw(); System.out.println("Player's second card: " + playercardB); System.out.println("Enemy's Turn: "); enemycardAdraw(); System.out.println("Enemy's first card: " + enemycardA); enemycardBdraw(); System.out.println("Enemy's Second card: " + enemycardB); } }

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  • Code Design question, circular reference across classes?

    - by dsollen
    I have no code here, as this is more of a design question (I assume this is still the best place to ask it). I have a very simple server in java which stores a mapping between certain values and UUID which are to be used by many systems across multiple platforms. It accepts a connection from a client and creates a clientSocket which stores the socket and all the other relevant data unique to that connection. Each clientSocket will run in their own thread and will block on the socket waiting for a read. I expect very little strain on this system, it will rarely get called, but when it does get a call it will need to respond quickly and due to the risk of it having a peak time with multiple calls coming in at once threaded is still better. Each thread has a reference to a Mapper class which stores the mapping of UUID which it's reporting to others (with proper synchronization of course). This all works until I have to add a new UUID to the list. When this happens I want to report to all clients that care about that particular UUID that a new one was added. I can't multicast (limitation of the system I'm running on) so I'm having each socket send the message to the client through the established socket. However, since each thread only knows about the socket it's waiting on I didn't have a clear method of looking up every thread/socket that cares about the data to inform them of the new UUID. Polling is out mostly because it seems a little too convoluted to try to maintain a list of newly added UUID. My solution as of now is to have the 'parent' class which creates the mapper class and spawns all the threads pass itself as an argument to the mapper. Then when the mapper creates a new UUID it can make a call to the parent class telling it to send out updates to all the other sockets that care about the change. I'm concerned that this may be a bad design due to the use of a circular reference; parent has a reference to mapper (to pass it to new ClientSocket threads) and mapper points to parent. It doesn't really feel like a bad design to me but I wanted to check since circular references are suppose to be bad. Note: I realize this means that the thread associated with whatever socket originally received the request that spawned the creation of a UUID is going to pay the 'cost' of outputting to all the other clients that care about the new UUID. I don't care about this; as I said I suspect the client to receive only intermittent messages. It's unlikely for one socket to receive multiple messages at one time, and there won't be that many sockets so it shouldn't take too long to send messages to each of them. Perhaps later I'll fix the fact that I'm saddling higher work load on whatever unfortunate thread gets the first request; but for now I think it's fine.

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  • How are OpenGL ES 1 framebuffers and textures sized?

    - by jens
    I am trying to draw to a texture using a framebuffer using OpenGL ES 1.1 on Android, Java. Afterwords I want to overlay this texture full-screen over my game. In theory, this works like a charm, but somehow the coordinates are off. For testing I drew something at (0,0) with width and height 200, and it partly is off-screen. This is how I create the framebuffer: fb = new int[1]; depthRb = new int[1]; renderTex = new int[1]; gl11ep.glGenFramebuffersOES(1, fb, 0); gl11ep.glGenRenderbuffersOES(1, depthRb, 0); // the depth buffer gl.glGenTextures(1, renderTex, 0);// generate texture gl.glBindTexture(GL10.GL_TEXTURE_2D, renderTex[0]); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); texBuffer = ByteBuffer.allocateDirect(buf.length*4).order(ByteOrder.nativeOrder()).asIntBuffer(); gl.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_LUMINANCE, texW, texH, 0, GL10.GL_LUMINANCE, GL10.GL_UNSIGNED_BYTE, texBuffer); gl11ep.glBindRenderbufferOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); gl11ep.glRenderbufferStorageOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, GL11ExtensionPack.GL_DEPTH_COMPONENT16, texW, texH); Before I draw, I do this: gl11ep.glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, fb[0]); gl.glClearColor(0f, 0f, 0f, 0f); // specify texture as color attachment gl11ep.glFramebufferTexture2DOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_COLOR_ATTACHMENT0_OES, GL10.GL_TEXTURE_2D, renderTex[0], 0); // attach render buffer as depth buffer gl11ep.glFramebufferRenderbufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_DEPTH_ATTACHMENT_OES, GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); I set texW = 1024 and texH = 512. When rendering this texture fullscreen, with a lightmask (size 200x200) placed at (0, 0) and (texW/2, texH/2). You can see that it seems like the coordinate system doesnt start at (0,0) as that light overlaps the screen and the images are not drawn as squares (my lightcone-texture is a circle, not an ellipse). So, how is the coordinate system of this offscreen-drawn texture defined? Thanks

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  • How is a switch statement better than a series of if statements? [closed]

    - by user1276078
    Possible Duplicate: Should I use switch statements or long if…else chains? I'm working on a small program that will conduct an Insertion Sort. A number will be inputted through the keyboard and stored in a variable I called "num." I've decided to use a switch statement in order to obtain the number inputted. switch( e.getKeyCode() ) { case KeyEvent.VK_0: num = 0; break; case KeyEvent.VK_1: num = 1; break; case KeyEvent.VK_2: num = 2; break; case KeyEvent.VK_3: num = 3; break; case KeyEvent.VK_4: num = 4; break; case KeyEvent.VK_5: num = 5; break; case KeyEvent.VK_6: num = 6; break; case KeyEvent.VK_7: num = 7; break; case KeyEvent.VK_8: num = 8; break; case KeyEvent.VK_9: num = 9; break; } I realized one other course of action could have been to use a set of if statements. if( e.getKeyCode() == KeyEvent.VK_0 ) num = 0; else if( e.getKeyCode() == KeyEvent.VK_1 ) num = 1; etc. for every number up until 9. I then wondered what the essential difference is between a switch statement and a series of if statements. I know it saves space and time to write, but it's not that much. So, my question is, aside from the space, does a switch statement differ from a series of if statments in any way? Is it faster, less error-prone, etc.? This question really doesn't affect my code that much. I was just wondering. Also, this question pertains to the JAVA language, not any other programming language.

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  • How best to look up objects by label?

    - by dsollen
    I am writing the server backed by a pre-written API. I'm going to get a number of strings representing ports, signals, paths, etc etc etc. I need to look up the object associated with a given label, these objects are all in memory (no sql magic to do this for me). My question is, how best do I associate a given unique label with the mutable object it represents? I have enough objects that looking through every signal or every port to find the one that matches is possible, but may be slightly too slow. To be honest the direct 'look at every object' method is probably good enough for so small a body of objects and anything else is premature optimization, but I still am curious what the proper solution would be if I thought my signals were going to grow a bit larger. As I see it there are two options available. First would be to to create a 'store' that is a simple map between object and label. I could have it so that every time I call addObject the object is automatically saved into a hashmap or the like. This works, but relies on my properly adding and deleting each object so the map doesn't grow indefinitely. The biggest issue to me is that this involves having some hidden static map in my ModelObject class that just feels...wrong somehow. The other option is to have some method that can interpret the labels. All of these labels are derived from the underlying objects. So I can look at the signal label, for instance, and say "these 20 characters are the port" to figure out what port I need. This would allow me to quickly figure out what I need. However, if the label method is changed the translateLabelToObject method needs to be updated as well or everything breaks. Which solution is cleaner, or possibly a cleaner solution than either of above? For the record I'm working with sufficient number of variables to make direct comparison a little slow, but not enough to be concerned about memory overhead, written in java. All objects that have labels I need to look up extend the same parent class.

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  • Les spécifications de Java EE 7 approuvées à l'unanimité par le JCP, IBM émet des réserves sur la modularité de la plate-forme

    Les spécifications de Java EE 7 approuvées à l'unanimité par le Java Community Process Mais IBM émet des réserves sur l'extensibilité et la modularité de la plateforme Mise à jour du 17/03/2011 par Idelways Les spécifications de la prochaine version de Java Entreprise Edition viennent d'être approuvées à l'unanimité par le Java Community Process. Douze des treize organisations impliquées dans les Java Specification Request (JSR), dont Google, la fondation Eclipse, Intel et SAP ont voté « oui sans commentaire » à la proposition d'Oracle. Seul IBM a joint des remarques à son vote positif. IBM ...

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  • (Android) How are OpenGL ES 1 framebuffers and textures sized?

    - by jens
    I am trying to draw to a texture using a framebuffer using OpenGL ES 1.1 on Android, Java. Afterwords I want to overlay this texture full-screen over my game. In theory, this works like a charm, but somehow the coordinates are off. For testing I drew something at (0,0) with width and height 200, and it partly is off-screen. This is how I create the framebuffer: fb = new int[1]; depthRb = new int[1]; renderTex = new int[1]; gl11ep.glGenFramebuffersOES(1, fb, 0); gl11ep.glGenRenderbuffersOES(1, depthRb, 0); // the depth buffer gl.glGenTextures(1, renderTex, 0);// generate texture gl.glBindTexture(GL10.GL_TEXTURE_2D, renderTex[0]); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); texBuffer = ByteBuffer.allocateDirect(buf.length*4).order(ByteOrder.nativeOrder()).asIntBuffer(); gl.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_LUMINANCE, texW, texH, 0, GL10.GL_LUMINANCE, GL10.GL_UNSIGNED_BYTE, texBuffer); gl11ep.glBindRenderbufferOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); gl11ep.glRenderbufferStorageOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, GL11ExtensionPack.GL_DEPTH_COMPONENT16, texW, texH); Before I draw, I do this: gl11ep.glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, fb[0]); gl.glClearColor(0f, 0f, 0f, 0f); // specify texture as color attachment gl11ep.glFramebufferTexture2DOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_COLOR_ATTACHMENT0_OES, GL10.GL_TEXTURE_2D, renderTex[0], 0); // attach render buffer as depth buffer gl11ep.glFramebufferRenderbufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_DEPTH_ATTACHMENT_OES, GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); I set texW = 1024 and texH = 512. When rendering this texture fullscreen, with a lightmask (size 200x200) placed at (0, 0) and (texW/2, texH/2). You can see that it seems like the coordinate system doesnt start at (0,0) as that light overlaps the screen and the images are not drawn as squares (my lightcone-texture is a circle, not an ellipse). So, how is the coordinate system of this offscreen-drawn texture defined? Thanks

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