Exiting game loop in JavaME freezes system

Question

I am working on developing JavaME games and am using an LG500G and Motorola EM326g as testing devices. At this very early stage, things are going wrong. I have a while(!stop){} game loop, and at a certain point a method will set stop to true, which will enter a block of code after the while loop, a sort of end-game condition. This always works fine in the emulator, in the various ways I have expressed it. However, I have never been able to get it to work on either of the phones. Instead, the game freezes and no further activity happens. The baffling thing is that when I compile code from other games I have studied which use the same looping mechanism, those games run as expected! What could I be doing wrong? Is there a way I could rephrase the code to get it to work? I am currently looking at a "game state manager" as a possible solution...but something as simple as this should just work!(by the way, I tried a simple while(!stop){} loop, but had to try an if(!stop){}else{} block within the while(true) loop. It did not work on the phones either:

    import java.io.IOException;
    import javax.microedition.lcdui.Graphics;
    import javax.microedition.lcdui.Image;
    import javax.microedition.lcdui.game.*;

    public class GardenGameCanvas extends GameCanvas implements Runnable{
private Image tomato;
private Sprite tomatoSprite;
private boolean stop;
private int tomX;
private int tomY;
private LayerManager manager;

    public GardenGameCanvas(){
    super(false);
}
public void start() {
    try{
        tomato = Image.createImage("/tomato.png");
        tomatoSprite = new Sprite(tomato, 16, 16);
        tomX= 0;
        tomY = getHeight()/2;
        manager = new LayerManager();
        manager.append(tomatoSprite);
        stop = false;

        }catch(IOException ioex){System.err.println(ioex);}
    Thread runner = new Thread(this);
    runner.start();

    }

public void run() {
    while(true){
        if(!stop){
        verifyGame();
        checkInput();
        update(getGraphics());
        try {
              Thread.currentThread().sleep(30);
            } catch(Exception e) {}

    }else{
    endGame(getGraphics());
    }
    }
}
private void update (Graphics g){
    g.setColor(0xFFFFFF); //white
    g.fillRect(0, 0, getWidth(), getHeight());
    buildGame(g);
    tomatoSprite.setPosition(tomX, tomY);
    manager.paint(g, 0, 0);
    flushGraphics();
}
private void buildGame(Graphics g){
    g.setColor(0x000000);
    g.drawLine(0, getHeight()/2, getWidth(), getHeight()/2);

}
private void checkInput(){
    int keyStates = getKeyStates();
    if((keyStates & LEFT_PRESSED) != 0) {
        tomX -= 1;
         }
else if((keyStates & RIGHT_PRESSED) != 0) {
        tomX += 1;
}
}
private void endGame(Graphics g){
    g.setColor(0xFFFFFF);
    g.fillRect(0,0,getWidth(), getHeight());
    g.setColor(0x000000);
    g.drawString("Game Over", getWidth()/2, getHeight()/2, Graphics.HCENTER);
    flushGraphics();
}
private void verifyGame(){
    if(tomX==getWidth()){
        stop = true;
        return;
    }
}
}

The error is probably in line 106. But I can't be sure as you haven't pasted any code. — mr_lou, Feb 04 '14 at 09:34

score 0 · Answer 1 · answered Feb 18 '14 at 23:03

I think the following is the problem: You are never ending the while-loop.

Emulator and device are handling threads an processes differently. Probably your run-thread takes all the time on the device.

Try for example the following:

while (true){
    if(!stop){
       ....
    }
    else {
       endGame();
       return;
    }
}

Exiting game loop in JavaME freezes system

1 Answers1