textboxexitmidlet.java

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package com.j2medev.sample.chapter3;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class TextBoxExitMidlet extends MIDlet implements CommandListener {
    
    private TextBox textBox = new TextBox("UIDemo", "能够响应用户Command的TextBox", 1024, TextField.ANY);
    //创建Command对象
    private Command exitCommand = new Command("退出", Command.EXIT, 1);
    private Command backCommand = new Command("返回",Command.BACK,2);
    private Command helpCommand = new Command("帮助",Command.ITEM, 3);
    
    private Display display = null;
    
    public void startApp() {
        if(display==null) {
            display = Display.getDisplay(this);
            display.setCurrent(textBox);
            //向TextBox添加Command，并注册CommandListener
            textBox.addCommand(exitCommand);
            textBox.addCommand(backCommand);
            textBox.addCommand(helpCommand);
            textBox.setCommandListener(this);
        }else{
            display.setCurrent(textBox);
        }
    }
    
    public void pauseApp() {
    }
    
    public void destroyApp(boolean unconditional) {
    }
    
    public void commandAction(Command cmd, Displayable displayable) {
        //如果某个Command被按下，那么它将作为参数传递给commandAction()
        if(cmd == exitCommand) {
            destroyApp(true);
            notifyDestroyed();
        }
    }
}