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Thread: Weird Error with java objectoutput/input streams

  1. #1
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    Default Weird Error with java objectoutput/input streams

    Hello,

    I am currently testing some networking with java as im going to start implementing it into XNA soon.

    So far, I've had quite a bit of success, but im starting from scratch and couldn't find enough examples, so i did some research on network loops, etc..

    anyways, I'm getting a weird error, I'll put my code into a couple of code blocks below, as well as the error I'm recieving at the end.


    --------------------THE CLIENT THREAD ON SERVER SIDE --------------------
    package OnlineGameTest;
    //The client that will communicating to the server.
     
     
    import java.awt.*;
    import java.awt.event.*;
    import java.io.*;
    import java.net.*;
    import java.util.ArrayList;
     
    import javax.swing.*;
     
    public class ClientGame extends JComponent implements ActionListener,
    		KeyListener {
    	Dimension clientBounds = new Dimension(600, 600);
    	int x = 100;
    	int y = 100;
    	int moveSpeed = 5;
    	Timer time;
    	Rectangle playerSize = new Rectangle(32, 32);
    	Socket serverSocket;
    	ObjectOutputStream os;
    	ObjectInputStream is;
    	PlayerData player = new PlayerData(100, 100, (byte) 0);
    	ArrayList<Byte> keyBuffer = new ArrayList<Byte>();
    	ArrayList<PlayerData> players = new ArrayList<PlayerData>();
    	int numbPlayers = 0;
    	boolean Up = false;
    	boolean Down = false;
    	boolean Left = false;
    	boolean Right = false;
    	// ----KEY CODES FOR BUFFER
    	public final byte UP_PRESSED = 10;
    	public final byte DOWN_PRESSED = 11;
    	public final byte LEFT_PRESSED = 12;
    	public final byte RIGHT_PRESSED = 13;
    	public final byte UP_RELEASED = 14;
    	public final byte DOWN_RELEASED = 15;
    	public final byte LEFT_RELEASED = 16;
    	public final byte RIGHT_RELEASED = 17;
     
    	Runnable networkLoop = new Runnable() {
     
    		@Override
    		public void run() {
    			try {
    				while (true) {
    					System.out.println("im in the loop!");
    					if (keyBuffer.size() > 0) {
    						// System.out.println("Keybuffer size: " +
    						// keyBuffer.size());
    						for (int i = 0; i < keyBuffer.size(); i++) {
    							if (keyBuffer.get(i) != null) {
    								switch (keyBuffer.get(i)) {
    								case UP_PRESSED:
    									os.writeByte(UP_PRESSED);
    									System.out.println("sent up!");
    									break;
    								case UP_RELEASED:
    									os.writeByte(UP_RELEASED);
    									break;
    								case DOWN_PRESSED:
    									os.writeByte(DOWN_PRESSED);
    									break;
    								case DOWN_RELEASED:
    									os.writeByte(DOWN_RELEASED);
    									break;
    								case LEFT_PRESSED:
    									os.writeByte(LEFT_PRESSED);
    									break;
    								case LEFT_RELEASED:
    									os.writeByte(LEFT_RELEASED);
    									break;
    								case RIGHT_PRESSED:
    									os.writeByte(RIGHT_PRESSED);
    									break;
    								case RIGHT_RELEASED:
    									os.writeByte(RIGHT_RELEASED);
    									break;
    								default:
    									System.out
    											.println("At least im doing something");
    									break;
    								}
    							}
    							os.flush();
    							keyBuffer.clear();
    						}
    					} else {
    						os.writeByte(0); // tell it at least connected
    						os.flush();
    					}
    					byte packetSize = is.readByte();
    					System.out.println(" : " + packetSize);
    					for (int i = 0; i < packetSize; i++) {
    						int theByte = is.read();
    						System.out.println("the byte: " + theByte);
    						switch (theByte) {
    						case 1:
    							System.out.println((String) is.readObject());
    							break;
     
    						case 2:
    							System.out.println("got player coords");
    							player.x = is.readFloat();
    							player.y = is.readFloat();
     
    							break;
    						case 3:
     
    							int numbPlayers = is.readByte();
    							for (int ii = 0; ii < numbPlayers; ii++) {
    								byte id = is.readByte();
    								int playerIndex = -1;
    								for (int iii = 0; iii < players.size(); iii++) {
    									if (players.get(iii).ID == id) {
    										playerIndex = ii;
    										players.get(iii).x = is.readFloat();
    										players.get(iii).y = is.readFloat();
    										break;
    									}
    								}
     
    								if (playerIndex == -1) {
    									numbPlayers += 1;
    									float x = is.readFloat();
    									float y = is.readFloat();
    									players.add(new PlayerData(x, y, id));
    								}
    							}
     
    						default:
    							System.out.println("shootin blanks");
    							break;
    						}
     
    					}
    				}
     
    			} catch (Exception e) {
    				e.printStackTrace();
    			}
     
    		}
     
    	};
     
    	Runnable send = new Runnable() {
     
    		@Override
    		public void run() {
    			try {
    				while (true) {
     
    				}
    			} catch (Exception e) {
    				e.printStackTrace();
    			}
     
    		}
     
    	};
     
    	public ClientGame() {
    		setVisible(true);
    		setPreferredSize(clientBounds);
    		setFocusable(true);
    		requestFocus();
    	}
     
    	public void Initialize() {
    		addKeyListener(this);
    		time = new Timer(17, this);
    		time.start();
    		requestFocus();
    		setUpConnection("127.0.0.1", 40046);
    	}
     
    	public void paintComponent(Graphics g) {
    		// TODO Auto-generated method stub
    		Graphics2D g2 = (Graphics2D) g;
    		g2.setColor(Color.orange);
    		g2.fillRect(0, 0, getWidth(), getHeight());
    		g2.setColor(Color.black);
     
    		g2.fillRect((int) player.x, (int) player.y, playerSize.width,
    				playerSize.height);
    		g2.setColor(Color.GRAY);
    		for (int i = 0; i < players.size(); i++) {
    			g2.fillRect((int) players.get(i).x, (int) players.get(i).y,
    					playerSize.width, playerSize.height);
    			g2.drawString(String.valueOf((int) players.get(i).ID),
    					(int) players.get(i).x, (int) players.get(i).y);
    		}
    	}
     
    	@Override
    	public void actionPerformed(ActionEvent e) {
    		if (e.getSource() == time) {
    			repaint();
    		}
     
    	}
     
    	@Override
    	public void keyTyped(KeyEvent e) {
     
    	}
     
    	@Override
    	public void keyPressed(KeyEvent e) {
    		if (e.getKeyCode() == KeyEvent.VK_UP && !Up) {
    			Up = true;
    			keyBuffer.add(UP_PRESSED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_DOWN && !Down) {
    			Down = true;
    			keyBuffer.add(DOWN_PRESSED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_RIGHT && !Right) {
    			Right = true;
    			keyBuffer.add(RIGHT_PRESSED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_LEFT && !Left) {
    			Left = true;
    			keyBuffer.add(LEFT_PRESSED);
    		}
     
    	}
     
    	@Override
    	public void keyReleased(KeyEvent e) {
    		if (e.getKeyCode() == KeyEvent.VK_UP) {
    			Up = false;
    			keyBuffer.add(UP_RELEASED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_DOWN) {
    			Down = false;
    			keyBuffer.add(DOWN_RELEASED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
    			Right = false;
    			keyBuffer.add(RIGHT_RELEASED);
    		}
    		if (e.getKeyCode() == KeyEvent.VK_LEFT) {
    			Left = false;
    			keyBuffer.add(LEFT_RELEASED);
    		}
     
    	}
     
    	public void setUpConnection(String ServerName, int port) {
    		try {
    			serverSocket = new Socket(ServerName, port);
    			os = new ObjectOutputStream(serverSocket.getOutputStream());
    			is = new ObjectInputStream(serverSocket.getInputStream());
    			Thread NetworkLoop = new Thread(networkLoop);
    			NetworkLoop.start();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
     
    }

    ----------------THE CLIENT THREAD ON THE SERVER SIDE -----------------

    package OnlineGameTest;
     
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.net.Socket;
    import java.util.ArrayList;
     
    public class ClientHandler {
    	public static Socket socket;
    	public static boolean Connected;
    	ObjectInputStream is;
    	ObjectOutputStream os;
    	PlayerData player;
    	public static int clientID;
    	boolean moveUp = false;
    	boolean moveDown = false;
    	boolean moveRight = false;
    	boolean moveLeft = false;
    	float playerSpeed = 5;
    	float oldX = 0f;
    	float oldY = 0f;
    	ArrayList<Byte> commandBuffer = new ArrayList<Byte>();
    	ArrayList<ClientHandler> tempClients = new ArrayList<ClientHandler>();
     
    	public ClientHandler(Socket clientSocket, int ID) {
     
    		this.socket = clientSocket;
    		player = new PlayerData(20f, 20f, (byte) ID);
    		Connected = true;
    		clientID = ID;
    		try {
    			is = new ObjectInputStream(clientSocket.getInputStream());
    			os = new ObjectOutputStream(clientSocket.getOutputStream());
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		Thread Networking = new Thread(networkLoop);
    		Networking.start();
    	}
     
    	public void Update() {
    		// System.out.println("playerX: " + player.x + " PlayerY: " + player.y);
    		if (moveUp) {
    			player.y -= playerSpeed;
    		}
    		if (moveDown) {
    			player.y += playerSpeed;
    		}
    		if (moveLeft) {
    			player.x -= playerSpeed;
    		}
    		if (moveRight) {
    			player.x += playerSpeed;
    		}
    	}
     
    	Runnable networkLoop = new Runnable() {
     
    		public void run() {
    			while (Connected) {
    				try {
    					Byte tempByte;
    					if ((tempByte = is.readByte()) != null) {
    						// System.out.println("Byte read: " + tempByte);
    						switch (tempByte) {
    						case GameServer.UP_PRESSED:
    							System.out.println("Recieved Up");
    							moveUp = true;
    							break;
    						case GameServer.UP_RELEASED:
    							System.out.println("Recieved up released!");
    							moveUp = false;
    							break;
    						case GameServer.DOWN_PRESSED:
    							moveDown = true;
    							break;
    						case GameServer.DOWN_RELEASED:
    							moveDown = false;
    							break;
    						case GameServer.LEFT_PRESSED:
    							moveLeft = true;
    							break;
    						case GameServer.LEFT_RELEASED:
    							moveLeft = false;
    							break;
    						case GameServer.RIGHT_PRESSED:
    							moveRight = true;
    							break;
    						case GameServer.RIGHT_RELEASED:
    							moveRight = false;
    							System.out.println("got right released");
    							break;
    						default:
    							break;
    						}
    					}
    					calculateCommands();
    					os.writeByte(commandBuffer.size()); // tells the client how
    														// big of a packet to
    														// read
    					for (int i = 0; i < commandBuffer.size(); i++) {
    						switch (commandBuffer.get(i)) {
    						case 0:
    							os.writeByte(0);
    						case 1:
    							os.writeByte(1);
    							os.writeObject("clientID: " + clientID
    									+ "is Connected");
    							break;
     
    						case 2:
    							os.writeByte(2);
    							os.writeFloat(player.x);
    							os.writeFloat(player.y);
    							oldX = player.x;
    							oldY = player.y;
    							break;
    						case 3:
    							os.writeByte(3);
    							tempClients.clear();
    							for(int ii = 0;ii < GameServer.Clients.size();ii++){ // calculate which need to be updated on client
    								if(GameServer.Clients.get(ii).clientID != clientID){
    									tempClients.add(GameServer.Clients.get(ii));
    								}
    							}
    							os.writeByte(tempClients.size());
    							for(int ii = 0; ii < tempClients.size();ii++){
    								os.writeByte(tempClients.get(ii).clientID);
    								os.writeFloat(tempClients.get(ii).player.x);
    								os.writeFloat(tempClients.get(ii).player.y);
    							}
    						case -1:
    							System.out.println("WTF");
    							break;
    						default:
    							break;
    						}
    					}
    					commandBuffer.clear();
    					os.flush();
     
    				} catch (Exception e) {
    					e.printStackTrace();
    				}
    			}
    		}
     
    	};
     
    	public void calculateCommands() {
    		if (player.x != oldX || player.y != oldY) {
    			commandBuffer.add((byte) 2);
    		} else {
    			commandBuffer.add((byte) 0);
    		}
    		;
     
    		if (GameServer.Clients.size() - 1 > 0) {
    			commandBuffer.add((byte) 3);
    		}
    	}
     
    }

    -----------------GAME SERVER ------------------

    package OnlineGameTest;
     
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.io.*;
    import java.net.*;
    import java.util.ArrayList;
     
    import javax.swing.Timer;
     
    public class GameServer{
    	int port = 40046;
    	ServerSocket serverIO;
    	ArrayList<Socket> clientSockets = new ArrayList<Socket>();
    	ObjectOutputStream os;
    	ObjectInputStream is;
    	Timer time;
    	int numbClients = 0;
    	public static final int MAX_CLIENTS = 10;
    	public static ArrayList<ClientHandler> Clients = new ArrayList<ClientHandler>();
    	//--- KEYBUFFER CODES
    	public static final byte UP_PRESSED = 10;
    	public static final byte DOWN_PRESSED = 11;
    	public static final byte LEFT_PRESSED = 12;
    	public static final byte RIGHT_PRESSED = 13;
    	public static final byte UP_RELEASED = 14;
    	public static final byte DOWN_RELEASED = 15;
    	public static final byte LEFT_RELEASED = 16;
    	public static final byte RIGHT_RELEASED = 17;
     
    	public static void main(String[] args){
    		new GameServer();
    	}
    	public GameServer() {
    		Initialize();
     
    	}
    	public Runnable acceptConnections = new Runnable(){
     
    		@Override
    		public void run() {
    			try{
    				System.out.println("Waiting for clients...");
    				while(true){
     
    					Socket temp = new Socket();
    					temp = serverIO.accept();
    					System.out.println(": " + Clients.size());
    					Clients.add(new ClientHandler(temp,Clients.size() + 1));
    					System.out.println("User Connected: " + temp.toString() + " ID: " + Clients.get(Clients.size()-1).clientID);
     
    				}
    			}
    			catch(Exception e){
    				e.printStackTrace();
    			}
     
    		}
     
    	};
    	public Runnable UpdateRun = new Runnable(){
     
    		@Override
    		public void run() {
    			time = new Timer(16,new ActionListener(){
     
    				@Override
    				public void actionPerformed(ActionEvent e) {
    					if(e.getSource() == time){
    						Update();
    					}
     
    				}
     
     
    			});
    			time.start();
     
    		}
     
     
    	};
     
     
    	public void Initialize() {
     
    		try{
    			serverIO = new ServerSocket(port);
    			Thread runAccepter = new Thread(acceptConnections);
    			runAccepter.start();
    			Thread startUpdate = new Thread(UpdateRun);
    			startUpdate.start();
     
     
    		}
     
    		catch(Exception e){
    			e.printStackTrace();
    		}
    	}
    	public void Update(){
    		for(int i = 0;i<Clients.size();i++){
    			if(Clients.get(i) != null){
    				Clients.get(i).Update();
    			}
    		}
    	}
    }

    Everything was working up well until i started implementing the code for the 3rd case statement for sending packets / recieving packets, from client handler to client game. I can't seem to fix that.

    this is the error that comes up, with some bug fixing println's i've included.

    im in the loop!
     : 1
    the byte: 2
    got player coords
    im in the loop!
     : 1
    the byte: 0
    shootin blanks
    im in the loop!
     : 1
    the byte: -1
    shootin blanks
    im in the loop!
    java.io.EOFException
    	at java.io.ObjectInputStream$BlockDataInputStream.readByte(ObjectInputStream.java:2745)
    	at java.io.ObjectInputStream.readByte(ObjectInputStream.java:913)
    	at OnlineGameTest.ClientGame$1.run(ClientGame.java:91)
    	at java.lang.Thread.run(Thread.java:722)





    Any tips regarding my code would be appreciated as well as the fix for this code!

    I'll attach the code itself aswell if anyone wants to take a go.
    Attached Files Attached Files


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Weird Error with java objectoutput/input streams

    java.io.EOFException
    Did you read the API doc for that class to see what the error means?
    the byte: -1
    Read the API doc for the read() method. -1 signals EOF.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    SparX (March 30th, 2013)

  4. #3
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    Default Re: Weird Error with java objectoutput/input streams

    Yeah i checked it out, I didn't understand why the stream was ending though, could you possibly give me some insight as to why it is ending the stream for no apparent reason?

  5. #4
    Super Moderator Norm's Avatar
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    Default Re: Weird Error with java objectoutput/input streams

    why it is ending the stream
    There was no more data in the stream.
    If you don't understand my answer, don't ignore it, ask a question.

  6. #5
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    Default Re: Weird Error with java objectoutput/input streams

    Oh i understand that, i'm really just curious as to why the stream keeps closing. I'll look over the code again but i dont understand why it is

  7. #6
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    Default Re: Weird Error with java objectoutput/input streams

    oh man, I found the problem, it's such a stupid one aswell, just forgot to put a break in one of the case statements.

    Thanks for the help though. You can get rid of this thread.

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