JME：如何在不使用按钮等的情况下以白色获取完整的屏幕

    public void startApp()         { f = new Form("Back Light On");d = Display.getDisplay(this);start = new Command("Turn On",Command.OK,0);stop = new Command("Turn Off",Command.OK,1);f.addCommand(start);f.setCommandListener(new Action());    myCanvas = new MyCanvas();     d.setCurrent(myCanvas);    myCanvas.repaint();}

现在创建一个画布并实现如下所示的paint方法：

  class MyCanvas extends Canvas { public void paint(Graphics g) {     // create a 20x20 black square in the center     // clear the screen first     g.setColor(0xffffff);     g.fillRect(0, 0, getWidth(), getHeight());     g.setColor(0xffffff); // make sure it is white color     // draw the square, <b>changed to rely on instance variables</b>     <b>g.fillRect(x, y, getWidth(), getHeight());</b> }        }