[J2ME] 基本框架框架

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.TextBox;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;


public class main extends MIDlet implements CommandListener {

    private Command exitCom;
    private Display ds;
    private TextBox tb;
    
    //构造函数
    public main() {
        // TODO Auto-generated constructor stub
        ds=Display.getDisplay(this);//创建Display类一个实体
        exitCom=new Command("Exit",Command.EXIT,1);//创建Command对象一个实体，并设置Exit命令用于退出这个MIDlet
        tb=new TextBox("Hellow MIDlet","Hellow World",15,0);//创建用来输出东西的TextBox对象
        tb.addCommand(exitCom);//使Command对象和TextBox关联起来
        tb.setCommandListener(this);//当TextBox显示在屏幕上时，使CommandListener响应发生的事件
    }

    protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
        // TODO Auto-generated method stub
        
    }

    //当系统要求MIDlet暂停时调用
    protected void pauseApp() {
        // TODO Auto-generated method stub

    }

    //第一次启动或者暂停后重启时由系统调用startApp()方法
    protected void startApp() throws MIDletStateChangeException {
        // TODO Auto-generated method stub
        ds.setCurrent(tb);//将构造函数中的TextBox设置为当前的屏幕
    }

    //用户触发任何Command是，做出回应，系统会自动调用这个方法
    public void commandAction(Command arg0, Displayable arg1) {
        // TODO Auto-generated method stub
        if(arg0==exitCom){
            try {
                destroyApp(false);
                notifyDestroyed();
            } catch (MIDletStateChangeException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

}