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 stub19         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MIDlet21         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 stub28         29     }30 31     //当系统要求MIDlet暂停时调用32     protected void pauseApp() {33         // TODO Auto-generated method stub34 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 stub40         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 stub46         if(arg0==exitCom){47             try {48                 destroyApp(false);49                 notifyDestroyed();50             } catch (MIDletStateChangeException e) {51                 // TODO Auto-generated catch block52                 e.printStackTrace();53             }54         }55     }56 57 }