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Question

源程序：
import java.applet.*;              
  import java.awt.*;                  
  import java.awt.event.*;            
  public class ImplementActionListener extends Applet implements ActionListener
  {                                  
   TextField password = new TextField("我是密码"); 
    Button btn = new Button("隐藏");   
    public void init()                 
   {                                 
    add(password);                  
     add(btn);                        
     btn.addActionListener(this);    
   }                                 
   public void actionPerform(ActionEvent e) 
   {                                 
     password.setEchoChar('*');
     password.selectAll();            
   }                                  
 } 
========================
错误提示：
--------------------Configuration: j2sdk1.4.0 <Default>--------------------
E:\javaexerces\ImplementActionListener.java:4: ImplementActionListener should be declared abstract; it does not define actionPerformed(java.awt.event.ActionEvent) in ImplementActionListener
  public class ImplementActionListener extends Applet implements ActionListener
         ^
1 errorProcess completed.

Answer 1

import java.applet.*;
import java.awt.*;
import java.awt.event.*;public class ImplementActionListener extends Applet implements ActionListener {
    TextField password = new TextField("我是密码");    Button btn = new Button("隐藏");    public void init() {
        add(password);
        add(btn);
        btn.addActionListener(this);
    }    public void actionPerform(ActionEvent e) {
        password.setEchoChar('*');
        password.selectAll();
    }    /* (non-Javadoc)
     * @see java.awt.event.ActionListener#actionPerformed(java.awt.event.ActionEvent)
     */
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        
    }
}