??? 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);
?}
?}

}
???

简单切屏的例子???