J2ME手机屏幕的切换 源码

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 TestFom2 extends MIDlet implements CommandListener{

private Display display;
private Form form = new Form("Welcome!!");
private Command okCommand = new Command("ok",Command.OK,1);//选择OK，换下一个屏幕
private Form ns;
private StringItem si = new StringItem("First Screen",null);

public TestFom2() {
// TODO 自动生成构造函数存根
form.addCommand(okCommand);
form.append(si);
}

protected void startApp() throws MIDletStateChangeException {
// TODO 自动生成方法存根
display = Display.getDisplay(this);
display.setCurrent(form);
form.setCommandListener(this);
}

protected void pauseApp() {
// TODO 自动生成方法存根

}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
// TODO 自动生成方法存根

}

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

}

}

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;

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",null);

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);
}
}
}