关于按钮的奇怪问题

package main;



import javax.microedition.lcdui.Command;

import javax.microedition.lcdui.CommandListener;

import javax.microedition.lcdui.Display;

import javax.microedition.lcdui.Displayable;

import javax.microedition.lcdui.Form;

import javax.microedition.midlet.MIDlet;

import javax.microedition.midlet.MIDletStateChangeException;



public class Test extends MIDlet implements CommandListener {



	private Display display;

	private Form form;

	private Command exit;



	public Test() {

		display = Display.getDisplay(this);

		exit = new Command("退出", Command.SCREEN, 1);

		form = new Form("测试Form");

		form.addCommand(exit);

		form.setCommandListener(this);

	}



	protected void destroyApp(boolean arg0) {}



	protected void pauseApp() {}



	protected void startApp() throws MIDletStateChangeException {

		display.setCurrent(form);

	}



	public void commandAction(Command c, Displayable d) {

		if (c == exit) {

			destroyApp(true);

			notifyDestroyed();

		}

	}



}