Paint Canvas in a thread : Thread « J2ME « Java Tutorial

1. Java Tutorial
2. J2ME
3. Thread

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;

public class J2MESweep extends MIDlet {
  public void startApp() {
    final SweepCanvas sweeper = new SweepCanvas();
    sweeper.start();

    sweeper.addCommand(new Command("Exit", Command.EXIT, 0));
    sweeper.setCommandListener(new CommandListener() {
      public void commandAction(Command c, Displayable s) {
        sweeper.stop();
        notifyDestroyed();
      }
    });

    Display.getDisplay(this).setCurrent(sweeper);
  }

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
  }
}

class SweepCanvas extends Canvas implements Runnable {
  private boolean mTrucking;

  private int mTheta = 0;

  private int mBorder = 10;

  private int mDelay = 50;

  public void start() {
    mTrucking = true;
    Thread t = new Thread(this);
    t.start();
  }

  public void stop() {
    mTrucking = false;
  }

  public void paint(Graphics g) {
    int width = getWidth();
    int height = getHeight();

    g.setGrayScale(255);
    g.fillRect(0, 0, width - 1, height - 1);

    int x = mBorder;
    int y = mBorder;
    int w = width - mBorder * 2;
    int h = height - mBorder * 2;
    for (int i = 0; i < 8; i++) {
      g.setGrayScale((8 - i) * 32 - 16);
      g.fillArc(x, y, w, h, mTheta + i * 10, 10);
    }
  }

  public void run() {
    while (mTrucking) {
      mTheta = (mTheta + 1) % 360;
      repaint();
      try {
        Thread.sleep(mDelay);
      } catch (InterruptedException ie) {
      }
    }
  }
}

31.23.Thread
	31.23.1.	Create a new thread
	31.23.2.	Paint Canvas in a thread
	31.23.3.	Thread in J2ME