j2me的list的 运用

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

 

public class mainApp extends MIDlet implements CommandListener{
 
 private Command cmd_back;
 private List lis;
 Display dis;
 public mainApp()
 {
  //lis=new List("我的列表",List.EXCLUSIVE);
  lis=new List("我的列表",List.IMPLICIT);
  //lis=new List("我的列表",List.MULTIPLE);
  lis.append("选项2",null);
  lis.append("选项1",null);
  lis.append("选项3",null);
  lis.append("选项4",null);
  lis.append("选项5",null);
  lis.append("选项6",null);
  cmd_back=new Command("确定",Command.SCREEN,1);
  lis.addCommand(cmd_back);
  lis.setCommandListener(this);
  dis=Display.getDisplay(this);
 }
 protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
  // TODO Auto-generated method stub
  
 }

 protected void pauseApp() {
  // TODO Auto-generated method stub
  
 }

 protected void startApp() throws MIDletStateChangeException {
  // TODO Auto-generated method stub
  dis.setCurrent(lis);
 }
 public void commandAction(Command arg0, Displayable arg1) {
  // TODO Auto-generated method stub
  if(arg0==cmd_back)
  {
       //获得list的被选择的索引值
    int Index=lis.getSelectedIndex();
    //通过索引值获得被选项的字符串
    String str= lis.getString(Index);
    //设置list的标题
    lis.setTitle(str);
  }
  
 }

}