import javax.microedition.lcdui.*;import javax.microedition.midlet.*;public class LayerManagerDemo extends MIDlet {  private MyCanvas canvas;      protected void startApp(  ) throws MIDletStateChangeException  {    canvas=new MyCanvas(this);   //創建MyCanvas屏幕畫布    Display.getDisplay(this).setCurrent(canvas);//顯示該畫布    canvas.start();//開始游戲線程  }  protected void pauseApp(  )  {    canvas.stop();//停止線程  }  protected void destroyApp( boolean unconditional )  {    canvas.stop();//停止線程  }   public void exitMidlet()  {    destroyApp(false);    notifyDestroyed();  }}