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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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• Simple task framework - building software from reusable pieces

  - by RuslanD

  I'm writing a web service with several APIs, and they will be sharing some of the implementation code. In order not to copy-paste, I would like to ideally implement each API call as a series of tasks, which are executed in a sequence determined by the business logic. One obvious question is whether that's the best strategy for code reuse, or whether I can look at it in a different way. But assuming I want to go with tasks, several issues arise: What's a good task interface to use? How do I pass data computed in one task to another task in the sequence that might need it? In the past, I've worked with task interfaces like: interface Task<T, U> { U execute(T input); } Then I also had sort of a "task context" object which had getters and setters for any kind of data my tasks needed to produce or consume, and it gets passed to all tasks. I'm aware that this suffers from a host of problems. So I wanted to figure out a better way to implement it this time around. My current idea is to have a TaskContext object which is a type-safe heterogeneous container (as described in Effective Java). Each task can ask for an item from this container (task input), or add an item to the container (task output). That way, tasks don't need to know about each other directly, and I don't have to write a class with dozens of methods for each data item. There are, however, several drawbacks: Each item in this TaskContext container should be a complex type that wraps around the actual item data. If task A uses a String for some purpose, and task B uses a String for something entirely different, then just storing a mapping between String.class and some object doesn't work for both tasks. The other reason is that I can't use that kind of container for generic collections directly, so they need to be wrapped in another object. This means that, based on how many tasks I define, I would need to also define a number of classes for the task items that may be consumed or produced, which may lead to code bloat and duplication. For instance, if a task takes some Long value as input and produces another Long value as output, I would have to have two classes that simply wrap around a Long, which IMO can spiral out of control pretty quickly as the codebase evolves. I briefly looked at workflow engine libraries, but they kind of seem like a heavy hammer for this particular nail. How would you go about writing a simple task framework with the following requirements: Tasks should be as self-contained as possible, so they can be composed in different ways to create different workflows. That being said, some tasks may perform expensive computations that are prerequisites for other tasks. We want to have a way of storing the results of intermediate computations done by tasks so that other tasks can use those results for free. The task framework should be light, i.e. growing the code doesn't involve introducing many new types just to plug into the framework.

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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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• Precise Touch Screen Dragging Issue: Trouble Aligning with the Finger due to Different Screen Resolution

  - by David Dimalanta

  Please, I need your help. I'm trying to make a game that will drag-n-drop a sprite/image while my finger follows precisely with the image without being offset. When I'm trying on a 900x1280 (in X [900] and Y [1280]) screen resolution of the Google Nexus 7 tablet, it follows precisely. However, if I try testing on a phone smaller than 900x1280, my finger and the image won't aligned properly and correctly except it still dragging. This is the code I used for making a sprite dragging with my finger under touchDragged(): x = ((screenX + Gdx.input.getX())/2) - (fruit.width/2); y = ((camera_2.viewportHeight * multiplier) - ((screenY + Gdx.input.getY())/2) - (fruit.width/2)); This code above will make the finger and the image/sprite stays together in place while dragging but only works on 900x1280. You'll be wondering there's camera_2.viewportHeight in my code. Here are for two reasons: to prevent inverted drag (e.g. when you swipe with your finger downwards, the sprite moves upward instead) and baseline for reading coordinate...I think. Now when I'm adding another orthographic camera named camera_1 and changing its setting, I recently used it for adjusting the falling object by meter per pixel. Also, it seems effective independently for smartphones that has smaller resolution and this is what I used here: show() camera_1 = new OrthographicCamera(); camera_1.viewportHeight = 280; // --> I set it to a smaller view port height so that the object would fall faster, decreasing the chance of drag force. camera_1.viewportWidth = 196; // --> Make it proportion to the original screen view size as possible. camera_1.position.set(camera_1.viewportWidth * 0.5f, camera_1.viewportHeight * 0.5f, 0f); camera_1.update(); touchDragged() x = ((screenX + (camera_1.viewportWidth/Gdx.input.getX()))/2) - (fruit.width/2); y = ((camera_1.viewportHeight * multiplier) - ((screenY + (camera_1.viewportHeight/Gdx.input.getY()))/2) - (fruit.width/2)); But the result instead of just following the image/sprite closely to my finger, it still has a space/gap between the sprite/image and the finger. It is possibly dependent on coordinates based on the screen resolution. I'm trying to drag the blueberry sprite with my finger. My expectation did not met since I want my finger and the sprite/image (blueberry) to stay close together while dragging until I release it. Here's what it looks like: I got to figure it out how to make independent on all screen sizes by just following the image/sprite closely to my finger while dragging even on most different screen sizes instead.

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• Push-Based Events in a Services Oriented Architecture

  - by Colin Morelli

  I have come to a point, in building a services oriented architecture (on top of Thrift), that I need to expose events and allow listeners. My initial thought was, "create an EventService" to handle publishing and subscribing to events. That EventService can use whatever implementation it desires to actually distribute the events. My client automatically round-robins service requests to available service hosts which are determined using Zookeeper-based service discovery. So, I'd probably use JMS inside of EventService mainly for the purpose of persisting messages (in the event that a service host for EventService goes down before it can distribute the message to all of the available listeners). When I started considering this, I began looking into the differences between Queues and Topics. Topics unfortunately won't work for me, because (at least for now), all listeners must receive the message (even if they were down at the time the event was pushed, or hadn't made a subscription yet because they haven't completed startup (during deployment, for example) - messages should be queued until the service is available). However, I don't want EventService to be responsible for handling all of the events. I don't think it should have the code to react to events inside of it. Each of the services should do what it needs with a given event. This would indicate that each service would need a JMS connection, which questions the value of having EventService at all (as the services could individually publish and subscribe to JMS directly). However, it also couples all of the services to JMS (when I'd rather that there be a single service that's responsible for determining how to distribute events). What I had thought was to publish an event to EventService, which pulls a configuration of listeners from some configuration source (database, flat file, irrelevant for now). It replicates the message and pushes each one back into a queue with information specific to that listener (so, if there are 3 listeners, 1 event would become 3 events in JMS). Then, another thread in EventService (which is replicated, running on multiple hots) would be pulling from the queue, attempting to make the service call to the "listener", and returning the message to the queue (if the service is down), or discarding the message (if the listener completed successfully). tl;dr If I have an EventService that is responsible for receiving events and delegating service calls to "event listeners," (which are really just endpoints on other services), how should it know how to craft the service call? Should I create a generic "Event" object that is shared among all services? Then, the EventService can just construct this object and pass it to the service call. Or is there a better answer to this problem entirely?

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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 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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• 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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• 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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• 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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• 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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• Series On Embedded Development (Part 2) - Build-Time Optionality

  - by user12612705

  In this entry on embedded development, I'm going to discuss build-time optionality (BTO). BTO is the ability to subset your software at build-time so you only use what is needed. BTO typically pertains more to software providers rather then developers of final products. For example, software providers ship source products, frameworks or platforms which are used by developers to build other products. If you provide a source product, you probably don't have to do anything to support BTO as the developers using your source will only use the source they need to build their product. If you provide a framework, then there are some things you can do to support BTO. Say you provide a Java framework which supports audio and video. If you provide this framework in a single JAR, then developers who only want audio are forced to ship their product with the video portion of your framework even though they aren't using it. In this case, support providing the framework in separate JARs...break the framework into an audio JAR and a video JAR and let the users of your framework decide which JARs to include in their product. Sometimes this is as simple as packaging, but if, for example, the video functionality is dependent on the audio functionality, it may require coding work to cleanly separate the two. BTO can also work at install-time, and this is sometimes overlooked. Let's say your building a phone application which can use Near Field Communications (NFC) if it's available on the phone, but it doesn't require NFC to work. Typically you'd write one app for all phones (saving you time)...both those that have NFC and those that don't, and just use NFC if it's there. However, for better efficiency, you can detect at install-time if the phone supports NFC and not install the NFC portion of your app if the phone doesn't support NFC. This requires that you write the app so it can run without the optional NFC code and that you write your install app so it can detect NFC and do the right thing at install-time. Supporting install-time optionality will save persistent footprint on the phone, something your customers will appreciate, your app "neighbors" will appreciate, and that you'll appreciate when they save static footprint for you. In the next article, I'll talk about runtime optionality.

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• Should the 12-String be in it's own class and why?

  - by MayNotBe

  This question is regarding a homework project in my first Java programming class (online program). The assignment is to create a "stringed instrument" class using (among other things) an array of String names representing instrument string names ("A", "E", etc). The idea for the 12-string is beyond the scope of the assignment (it doesn't have to be included at all) but now that I've thought of it, I want to figure out how to make it work. Part of me feels like the 12-String should have it's own class, but another part of me feels that it should be in the guitar class because it's a guitar. I suppose this will become clear as I progress but I thought I would see what kind of response I get here. Also, why would they ask for a String[] for the instrument string names? Seems like a char[] makes more sense. Thank you for any insight. Here's my code so far (it's a work in progress): public class Guitar { private int numberOfStrings = 6; private static int numberOfGuitars = 0; private String[] stringNotes = {"E", "A", "D", "G", "B", "A"}; private boolean tuned = false; private boolean playing = false; public Guitar(){ numberOfGuitars++; } public Guitar(boolean twelveString){ if(twelveString){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = 12; } } public int getNumberOfStrings() { return numberOfStrings; } public void setNumberOfStrings(int strings) { if(strings == 12 || strings == 6) { if(strings == 12){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = strings; } if(strings == 6) numberOfStrings = strings; }//if else System.out.println("***ERROR***Guitar can only have 6 or 12 strings***ERROR***"); } public void getStringNotes() { for(int i = 0; i < stringNotes.length; i++){ if(i == stringNotes.length - 1) System.out.println(stringNotes[i]); else System.out.print(stringNotes[i] + ", "); }//for }

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• howto only tunnel specific hosts route through openvpn client on tomato

  - by kcome

  I am relatively newbie in networking world although I did coding and know some sysadmin background for a long time. and here I'm only one step from my destination. The whole picture is : at home I use one LinkSys E3000 as the gateway(don't know yet if this is it's name), wireless AP and no other routing/switching devices. It serves 1 PC and 1 Mac with LAN, 1 Mac Mini + 1 iPad + 2 smartphones with WIFI. My goal is use an openvpn client on the E3000 (with tomato firmware) and make my iPad and smartphone's all WiFi traffic through it, and other devices route remain the same non-openvpn route. So far I'm able to connect openvpn client on E3000 to an openvpn server, tunnel all my devices' all traffic through that openvpn connection. What's left is howto selectively route by source IP (at least in my guessing) to the tunnel while don't bother others. I had learned some 'iptables' and 'route' in past few days however without much luck, so here comes my question. Here are some info which will help you get the structure. ifconfig -a output, some useless lines striped, and in the web interface C0:C1:C0:1A:E0:28 is WAN, C0:C1:C0:1A:E0:27 is LAN, C0:C1:C0:1A:E0:29 is 2.4G wifi AP, C0:C1:C0:1A:E0:2A is 5G wifi AP. root@router:/tmp/home/root# ifconfig -a br0 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth0 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:29 UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 eth2 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:2A UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host ppp0 Link encap:Point-to-Point Protocol inet addr:172.200.1.43 P-t-P:172.200.0.1 Mask:255.255.255.255 UP POINTOPOINT RUNNING MULTICAST MTU:1480 Metric:1 vlan1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 vlan2 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:28 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 wl0.1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:29 BROADCAST MULTICAST MTU:1500 Metric:1 brctl show output root@router:/tmp/home/root# brctl show bridge name bridge id STP enabled interfaces br0 8000.c0c1c01ae027 no vlan1 eth1 eth2 before openvpn route-up script root@router:/tmp/home/root# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 172.200.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 br0 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo 0.0.0.0 172.200.0.1 0.0.0.0 UG 0 0 0 ppp0 openvpn server push PUSH: Received control message: 'PUSH_REPLY,redirect-gateway,dhcp-option DNS 8.8.8.8,route 172.20.0.1,topology net30,ping 10,ping-restart 120,ifconfig 172.20.0.6 172.20.0.5' openvpn's stock route-up script Apr 24 14:52:06 router daemon.notice openvpn[1768]: /sbin/ifconfig tun11 172.20.0.6 pointopoint 172.20.0.5 mtu 1500 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 72.14.177.29 netmask 255.255.255.255 gw 172.200.0.1 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 0.0.0.0 netmask 128.0.0.0 gw 172.20.0.5 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 128.0.0.0 netmask 128.0.0.0 gw 172.20.0.5 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 172.20.0.1 netmask 255.255.255.255 gw 172.20.0.5 route after openvpn root@router:/tmp/home/root# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 172.20.0.5 0.0.0.0 255.255.255.255 UH 0 0 0 tun11 72.14.177.29 172.200.0.1 255.255.255.255 UGH 0 0 0 ppp0 172.200.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 172.20.0.1 172.20.0.5 255.255.255.255 UGH 0 0 0 tun11 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 br0 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo 0.0.0.0 172.20.0.5 128.0.0.0 UG 0 0 0 tun11 128.0.0.0 172.20.0.5 128.0.0.0 UG 0 0 0 tun11 0.0.0.0 172.200.0.1 0.0.0.0 UG 0 0 0 ppp0 something I had noticed and tried: * on the web interface of openvpn client there is an option "Create NAT on tunnel", if i check this, there is the following script (probably executed after openvpn connection established) root@router:/tmp/home/root# cat /tmp/etc/openvpn/fw/client1-fw.sh #!/bin/sh iptables -I INPUT -i tun11 -j ACCEPT iptables -I FORWARD -i tun11 -j ACCEPT iptables -t nat -I POSTROUTING -s 192.168.1.0/255.255.255.0 -o tun11 -j MASQUERADE if i uncheck this option, the last line will not appear. Then I guess probably the my issue will be solved by iptables and NAT related commands, I just haven't got enough knowledge to figure them out. I tried run iptables -t nat -I POSTROUTING -s 192.168.1.6 -o tun11 -j MASQUERADE manually after openvpn connected (192.168.1.6 is the ip address of my iPad), then my iPad get internet with openvpn tunnel, however all other devices can't reach internet. in case if needed, here is the iptables about NAT root@router:/tmp/home/root# iptables -t nat -L -n Chain PREROUTING (policy ACCEPT) target prot opt source destination DROP all -- 0.0.0.0/0 192.168.1.0/24 WANPREROUTING all -- 0.0.0.0/0 172.200.1.43 upnp all -- 0.0.0.0/0 172.200.1.43 Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 SNAT all -- 192.168.1.0/24 192.168.1.0/24 to:192.168.1.1 Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain WANPREROUTING (1 references) target prot opt source destination DNAT icmp -- 0.0.0.0/0 0.0.0.0/0 to:192.168.1.1 Chain upnp (1 references) target prot opt source destination DNAT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:5353 to:192.168.1.3:5353 Thanks in advance for helping and read this so much, I hope i made every info you need to give a help :)

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• Getting problem in accessing web cam.

  - by Chetan

  Hi... I have written code in Java to access web cam,and to save image... I am getting following exceptions : Exception in thread "main" java.lang.NullPointerException at SwingCapture.(SwingCapture.java:40) at SwingCapture.main(SwingCapture.java:66) how to remove this exceptions. here is the code: import javax.swing.*; import javax.swing.event.; import java.io.; import javax.media.; import javax.media.format.; import javax.media.util.; import javax.media.control.; import javax.media.protocol.; import java.util.; import java.awt.; import java.awt.image.; import java.awt.event.; import com.sun.image.codec.jpeg.; public class SwingCapture extends Panel implements ActionListener { public static Player player = null; public CaptureDeviceInfo di = null; public MediaLocator ml = null; public JButton capture = null; public Buffer buf = null; public Image img = null; public VideoFormat vf = null; public BufferToImage btoi = null; public ImagePanel imgpanel = null; public SwingCapture() { setLayout(new BorderLayout()); setSize(320,550); imgpanel = new ImagePanel(); capture = new JButton("Capture"); capture.addActionListener(this); String str1 = "vfw:iNTEX IT-308 WC:0"; String str2 = "vfw:Microsoft WDM Image Capture (Win32):0"; di = CaptureDeviceManager.getDevice(str2); ml = di.getLocator(); try { player = Manager.createRealizedPlayer(ml); player.start(); Component comp; if ((comp = player.getVisualComponent()) != null) { add(comp,BorderLayout.NORTH); } add(capture,BorderLayout.CENTER); add(imgpanel,BorderLayout.SOUTH); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { Frame f = new Frame("SwingCapture"); SwingCapture cf = new SwingCapture(); f.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { playerclose(); System.exit(0);}}); f.add("Center",cf); f.pack(); f.setSize(new Dimension(320,550)); f.setVisible(true); } public static void playerclose() { player.close(); player.deallocate(); } public void actionPerformed(ActionEvent e) { JComponent c = (JComponent) e.getSource(); if (c == capture) { // Grab a frame FrameGrabbingControl fgc = (FrameGrabbingControl) player.getControl("javax.media.control.FrameGrabbingControl"); buf = fgc.grabFrame(); // Convert it to an image btoi = new BufferToImage((VideoFormat)buf.getFormat()); img = btoi.createImage(buf); // show the image imgpanel.setImage(img); // save image saveJPG(img,"\test.jpg"); } } class ImagePanel extends Panel { public Image myimg = null; public ImagePanel() { setLayout(null); setSize(320,240); } public void setImage(Image img) { this.myimg = img; repaint(); } public void paint(Graphics g) { if (myimg != null) { g.drawImage(myimg, 0, 0, this); } } } public static void saveJPG(Image img, String s) { BufferedImage bi = new BufferedImage(img.getWidth(null), img.getHeight(null), BufferedImage.TYPE_INT_RGB); Graphics2D g2 = bi.createGraphics(); g2.drawImage(img, null, null); FileOutputStream out = null; try { out = new FileOutputStream(s); } catch (java.io.FileNotFoundException io) { System.out.println("File Not Found"); } JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bi); param.setQuality(0.5f,false); encoder.setJPEGEncodeParam(param); try { encoder.encode(bi); out.close(); } catch (java.io.IOException io) { System.out.println("IOException"); } } }

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• Getting parameter sent via html form and saving in my db

  - by Wesley

  I have error in my code i don't know to solve it please help me: My Servlet: package br.com.cad.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.Date; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import br.com.cad.dao.Cadastro; import br.com.cad.basica.Contato; public class AddDados extends HttpServlet{ protected void service(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { PrintWriter out = response.getWriter(); String nome = request.getParameter("nome"); String sobrenome = request.getParameter("sobrenome"); String rg = request.getParameter("rg"); String cpf = request.getParameter("cpf"); String sexo = request.getParameter("sexo"); StringBuilder finalDate = new StringBuilder("DataNascimento1") .append("/"+request.getParameter("DataNascimento??2")) .append("/"+request.getParameter("DataNascimento3")); try { SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy"); finalDate.toString(); } catch(ParseException e) { out.println("Erro de conversão da data"); return; } Contato contato = new Contato(); contato.setNome(nome); contato.setSobrenome(sobrenome); contato.setRg(rg); contato.setCpf(cpf); contato.setSexo(sexo); if ("Masculino".equals(contato.getSexo())) { contato.setSexo("M"); } else { contato.setSexo("F"); } contato.setDataNascimento1(dataNascimento1); //error here ????? contato.setDataNascimento2(dataNascimento2); //error here ????? contato.setDataNascimento3(dataNascimento3); //error here ????? Cadastro dao = new Cadastro(); dao.adiciona(contato); out.println("<html>"); out.println("<body>"); out.println("Contato " + contato.getNome() + " adicionado com sucesso"); out.println("</body>"); out.println("</html>"); } } My object dao package br.com.cad.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.sql.Date; import br.com.cad.dao.ConnectDb; import br.com.cad.basica.Contato; public class Cadastro { private Connection connection; public Cadastro() { this.connection = new ConnectDb().getConnection(); } public void adiciona(Contato contato) { String sql = "INSERT INTO dados_cadastro(pf_nome, pf_ultimonome, pf_rg, pf_cpf, pf_sexo,pf_dt_nasc) VALUES(?,?,?,?,?,?,?,?)"; try { PreparedStatement stmt = connection.prepareStatement(sql); stmt.setString(1, contato.getNome()); stmt.setString(2, contato.getSobrenome()); stmt.setString(3, contato.getRg()); stmt.setString(4, contato.getCpf()); stmt.setString(5, contato.getSexo()); stmt.setDate(6, new Date( contato.getDataNascimento1().getTimeInMillis()) ); // i think there are error here i don't know to solve it ????? stmt.execute(); stmt.close(); System.out.println("Cadastro realizado com sucesso!."); } catch(SQLException sqlException) { throw new RuntimeException(sqlException); } } } My class cadastro package br.com.cad.basica; import java.util.Calendar; public class Contato { private Long id; private String nome; private String sobrenome; private String email; private String endereco; private Calendar dataNascimento1; private Calendar dataNascimento2; private Calendar dataNascimento3; private String rg; private String cpf; private String sexo; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getNome() { return nome; } public void setNome(String nome) { this.nome = nome; } ...getters and setters I need to saving data in my mysql db, but i have some doubt about this code main how to get parameter send form html combobox( 1 for day, 2 for month, 3 for year of birth) i concatened with StringBuilder finalDate ... so i have some problem in my code please help me!!!

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• Parsing XHTML results from Bing

  - by Nir

  Hello, i am trying to parse received search queries from bing search engines which are received in xhtml in java. I am using sax XmlReader to read the results but i keep on getting errors. here is my code-this one is for the hadler of the reader: import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class XHTMLHandler extends DefaultHandler{ public XHTMLHandler() { super(); } public void startDocument () { System.out.println("Start document"); } public void endDocument () { System.out.println("End document"); } public void startElement (String uri, String name,String qName, Attributes atts) { if ("".equals (uri)) System.out.println("Start element: " + qName); else System.out.println("Start element: {" + uri + "}" + name); } public void endElement (String uri, String name, String qName) { if ("".equals (uri)) System.out.println("End element: " + qName); else System.out.println("End element: {" + uri + "}" + name); } public void startPrefixMapping (String prefix, String uri) throws SAXException { } public void endPrefixMapping (String prefix) throws SAXException { } public void characters (char ch[], int start, int length) { System.out.print("Characters: \""); for (int i = start; i < start + length; i++) { switch (ch[i]) { case '\\': System.out.print("\\\\"); break; case '"': System.out.print("\\\""); break; case '\n': System.out.print("\\n"); break; case '\r': System.out.print("\\r"); break; case '\t': System.out.print("\\t"); break; default: System.out.print(ch[i]); break; } } System.out.print("\"\n"); } } and this is the program itself: import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.net.HttpRetryException; import java.net.HttpURLConnection; import java.net.URL; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import org.xml.sax.XMLReader; import org.xml.sax.helpers.XMLReaderFactory; public class Searching { private String m_urlBingSearch = "http://www.bing.com/search?q="; private HttpURLConnection m_httpCon; private OutputStreamWriter m_streamWriter; //private BufferedReader m_bufferReader; private URL m_serverAdress; private StringBuilder sb; private String m_line; private InputSource m_inputSrc; public Searching() { m_httpCon = null; m_streamWriter = null; //m_bufferReader = null; m_serverAdress = null; sb = null; m_line = new String(); } public void SearchBing(String searchPrms) throws SAXException,IOException { //set up connection sb = new StringBuilder(); sb.append(m_urlBingSearch); sb.append(searchPrms); m_serverAdress = new URL(sb.toString()); m_httpCon = (HttpURLConnection)m_serverAdress.openConnection(); m_httpCon.setRequestMethod("GET"); m_httpCon.setDoOutput(true); m_httpCon.setConnectTimeout(10000); m_httpCon.connect(); //m_streamWriter = new OutputStreamWriter(m_httpCon.getOutputStream()); //m_bufferReader = new BufferedReader(new InputStreamReader(m_httpCon.getInputStream())); XMLReader reader = XMLReaderFactory.createXMLReader(); XHTMLHandler handle = new XHTMLHandler(); reader.setContentHandler(handle); reader.setErrorHandler(handle); //reader.startPrefixMapping("html", "http://www.w3.org/1999/xhtml"); handle.startPrefixMapping("html", "http://www.w3.org/1999/xhtml"); m_inputSrc = new InputSource(m_httpCon.getInputStream()); reader.parse(m_inputSrc); m_httpCon.disconnect(); } public static void main(String [] args) throws SAXException,IOException { Searching s = new Searching(); s.SearchBing("beatles"); } } this is my error message: Exception in thread "main" java.io.IOException: Server returned HTTP response code: 503 for URL: http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startDTDEntity(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.setInputSource(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source) at Searching.SearchBing(Searching.java:57) at Searching.main(Searching.java:65) can someone please help? i think it has something to do with dtd but i don't know hot to fix it

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• How to understand these lines in apache.log

  - by chefnelone

  I just get 19000 lines like these in the apache.log file for my site example.com. My hosting provider shut down the hosting and notified me that I need to avoid to activate my hosting again. I understand that I got a big amount of visits but I don't know how to avoid this. 88.190.47.233 - - [27/Jun/2013:09:51:34 +0200] "GET / HTTP/1.0" 403 389 "http://example.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.10.289 Version/12.02" 417 88.190.47.233 - - [27/Jun/2013:09:51:34 +0200] "GET / HTTP/1.0" 403 389 "http://example.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.10.289 Version/12.02" 417 175.44.28.155 - - [27/Jun/2013:09:51:44 +0200] "GET /en/user/register HTTP/1.1" 403 503 "http://example.com/en/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;)" 248 175.44.29.140 - - [27/Jun/2013:09:53:19 +0200] "GET /en/node/1557?page=2 HTTP/1.0" 403 517 "http://example.com/en/node/1557?page=2" "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.12 Safari/535.11" 491 These are the lines from apache-error.log. There are more than 35000 lines like this. [Thu Jun 27 09:50:58 2013] [error] [client 5.39.19.183] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:03 2013] [error] [client 125.112.29.105] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:51:44 2013] [error] [client 175.44.28.155] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:53:19 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:56:53 2013] [error] [client 113.246.6.147] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:58:58 2013] [error] [client 108.62.71.180] (13)Permission denied: access to /index.php denied, referer: http://example.com/

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