Java Tutorial/J2ME/Thread

Create a new thread

import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.StringItem;
import javax.microedition.midlet.MIDlet;
public class J2METhreadTest extends MIDlet implements CommandListener {
  private Form form = new Form("Thread Test");
  private StringItem text = new StringItem("Current Thread:", Thread.currentThread().getName());
  private Display display;
  public J2METhreadTest() {
    form.append(text);
    form.addCommand(new Command("Exit", Command.EXIT, 1));
    form.addCommand(new Command("New Thread", Command.SCREEN, 1));
    form.setCommandListener(this);
    display = Display.getDisplay(this);
  }
  public void startApp() {
    display.setCurrent(form);
  }
  public void pauseApp() {
  }
  public void destroyApp(boolean unconditional) {
  }
  public void commandAction(Command cmd, Displayable disp) {
    if (cmd.getLabel().equals("Exit")) {
      notifyDestroyed();
    } else {
      Thread runner = new Thread(new ThreadRunner(display));
      runner.start();
    }
  }
}
class ThreadRunner implements Runnable {
  Display display;
  ThreadRunner(Display display) {
    this.display = display;
  }
  public void run() {
    display.setCurrent(new Alert(Thread.currentThread().getName()));
    try {
      Thread.sleep(3000);
    } catch (Exception e) {
    }
  }
}

Paint Canvas in a thread

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
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) {
      }
    }
  }
}

Thread in J2ME

import java.io.IOException;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.MIDlet;
public class J2MEBackgroundProcessing extends MIDlet implements CommandListener {
  private Display display;
  private Form form= new Form("Background Processing");
  private Command exit = new Command("Exit", Command.EXIT, 1);
  private Command start = new Command("Start", Command.SCREEN, 2);
  public J2MEBackgroundProcessing() {
    display = Display.getDisplay(this);
    form.addCommand(exit);
    form.addCommand(start);
    form.setCommandListener(this);
  }
  public void startApp() {
    display.setCurrent(form);
  }
  public void pauseApp() {
  }
  public void destroyApp(boolean unconditional) {
  }
  public void commandAction(Command command, Displayable displayable) {
    if (command == exit) {
      destroyApp(false);
      notifyDestroyed();
    } else if (command == start) {
      Process process = new Process(this);
      process.start();
    }
  }
}
class Process implements Runnable {
  private BackgroundProcessing MIDlet;
  public Process(BackgroundProcessing MIDlet) {
    this.MIDlet = MIDlet;
  }
  public void run() {
    try {
      transmit();
    } catch (Exception error) {
      System.err.println(error.toString());
    }
  }
  public void start() {
    Thread thread = new Thread(this);
    try {
      thread.start();
    } catch (Exception error) {
    }
  }
  private void transmit() throws IOException {
  }
}