j2me實現登陸框

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class Midlet1 extends MIDlet implements ItemCommandListener {

 private Form main;
 private TextField tf1;
 private TextField tf2;
 private Display dis;
 private Command cmd_1;
 public Midlet1()
 {
  main=new Form("登錄框");
  tf1=new TextField("賬號","",20,TextField.ANY);
  tf2=new TextField("輸入密碼","",20,TextField.PASSWORD);
  cmd_1=new Command("清除內容1",Command.ITEM,1);
  dis=Display.getDisplay(this);
  
  
  tf1.addCommand(cmd_1);
  tf1.setItemCommandListener(this);
  tf2.addCommand(cmd_1);
  tf2.setItemCommandListener(this);
  
  
  main.append(tf1);
  main.append(tf2);
 }
 protected void startApp() throws MIDletStateChangeException {
  // TODO Auto-generated method stub
  dis.setCurrent(main);
 }

 public void commandAction(Command arg0, Item arg1) {
  // TODO Auto-generated method stub
  if(arg0==cmd_1)
  {
   TextField tf=(TextField)arg1;
   int position=tf.getCaretPosition();
   tf.delete(position-1, 1);
  }
  
 }

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

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

}