写一个J2ME HelloWorld 的例子

    helloWorld.java：

           package com.org.mobile.HelloWord;

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.lcdui.StringItem;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class HelloWord extends MIDlet implements CommandListener  {
 private Display display;
 private Form form = new Form("Wellcome!!");
 private Command okCommand = new Command("OK",Command.OK,1);
 private Form ns ;
 private StringItem si = new StringItem("First Screen","~_~");
 public HelloWord() {
  form.addCommand(okCommand);
  form.append(si);
 }

 protected void destroyApp(boolean unconditional)
   throws MIDletStateChangeException {
    System.out.println("destroyApp is called.");

 }

 protected void pauseApp() {
    System.out.println("pauseApp is called.");

 }
 public void commandAction(Command c,Displayable s)
 {
 if(c==okCommand)
 {
 ns = new NextScreen(display,form);

 display.setCurrent(ns);
 }

 }

 protected void startApp() throws MIDletStateChangeException {
  display = Display.getDisplay(this);

  display.setCurrent(form);
  form.setCommandListener(this);//对form加入CommandListener
 }

}

NextScreen.java :

 

package com.org.mobile.HelloWord;

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.lcdui.StringItem;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class NextScreen extends Form implements CommandListener {

 private Display display;
 private Displayable parent;
 private Command backCommand = new Command("BACK",Command.BACK,1);
 private StringItem si = new StringItem("SecondScrean","~_~");
 public NextScreen(Display d,Displayable p)
 {
 super("nextscreen");
 display = d;
 parent = p;
 append(si);
 addCommand(backCommand);
 setCommandListener(this);

 }

 public void commandAction(Command c,Displayable s)
 {
 //返回上一个屏幕

 if(c==backCommand)
 {
 display.setCurrent(parent);
 }
 }

}
   

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