1 import javax.microedition.lcdui.Command;
 2 import javax.microedition.lcdui.CommandListener;
 3 import javax.microedition.lcdui.Display;
 4 import javax.microedition.lcdui.Displayable;
 5 import javax.microedition.lcdui.TextBox;
 6 import javax.microedition.midlet.MIDlet;
 7 import javax.microedition.midlet.MIDletStateChangeException;
 8 
 9 
10 public class main extends MIDlet implements CommandListener {
11 
12     private Command exitCom;
13     private Display ds;
14     private TextBox tb;
15     
16     //构造函数
17     public main() {
18         // TODO Auto-generated constructor stub
19         ds=Display.getDisplay(this);//创建Display类一个实体
20         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
21         tb=new TextBox("Hellow MIDlet","Hellow World",15,0);//创建用来输出东西的TextBox对象
22         tb.addCommand(exitCom);//使Command对象和TextBox关联起来
23         tb.setCommandListener(this);//当TextBox显示在屏幕上时，使CommandListener响应发生的事件
24     }
25 
26     protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
27         // TODO Auto-generated method stub
28         
29     }
30 
31     //当系统要求MIDlet暂停时调用
32     protected void pauseApp() {
33         // TODO Auto-generated method stub
34 
35     }
36 
37     //第一次启动或者暂停后重启时由系统调用startApp()方法
38     protected void startApp() throws MIDletStateChangeException {
39         // TODO Auto-generated method stub
40         ds.setCurrent(tb);//将构造函数中的TextBox设置为当前的屏幕
41     }
42 
43     //用户触发任何Command是，做出回应，系统会自动调用这个方法
44     public void commandAction(Command arg0, Displayable arg1) {
45         // TODO Auto-generated method stub
46         if(arg0==exitCom){
47             try {
48                 destroyApp(false);
49                 notifyDestroyed();
50             } catch (MIDletStateChangeException e) {
51                 // TODO Auto-generated catch block
52                 e.printStackTrace();
53             }
54         }
55     }
56 
57 }