初学java之事件响应（结合接口来设置在同一个界面上！）

 package wahaha;

 public class test_1 {
     public static void main( String args[] )
     {
         WindowActionEvent win = new WindowActionEvent();
         PoliceListen police = new PoliceListen(); //创建监视器
         win.setMyCommandListener(police);
         win.setBounds(100, 100, 460, 360);
         win.setTitle("处理ACtionEvent事件");
     }
 }

main_class

 package wahaha;

 import javax.swing.*;
 import java.awt.*;

 public class WindowActionEvent extends JFrame
 {

     JTextField inputText ;
     JTextArea testshow ;
     JButton button ;
     MyCommandListener listenner ;

     public WindowActionEvent()
     {
         init();
         setVisible(true);
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }

     void init()
     {
       setLayout(new FlowLayout());
       inputText =new JTextField(10);
       button =new JButton("确定");
       testshow = new JTextArea(9,30);
       add(inputText);
       add(button);
       add(new JScrollPane(testshow));
     }

     void setMyCommandListener(MyCommandListener listener)
     {
         this.listenner = listener ;
         listener.setJTextArea(testshow);
         listener.setJTextField(inputText);
                                     //inputText是事件源，listener是监视器
         button.addActionListener(listener) ;
                                     //button是事件源 ，listener是监视器
     }
 }

demo

  package wahaha;

 //设置一个接口 implements/interface/extends

 import javax.swing.* ;
 import java.awt.event.* ;

 public interface MyCommandListener extends ActionListener    //子接口多给出了2个方法
 {
    public void setJTextField(JTextField text);
    public void setJTextArea(JTextArea area);
 }

   package wahaha;

   import javax.swing.*;
   import java.awt.event.*;

   public class PoliceListen implements MyCommandListener
   {
     JTextField textInput ;
     JTextArea textshow ;

    public void setJTextField( JTextField text )
    {
      textInput = text ;
    }

    public void setJTextArea(JTextArea area)
    {
        textshow = area;
    }

    public void actionPerformed( ActionEvent e)
    {
        String str=textInput.getText();
        textshow.append(str+"的长度："+str.length()+"\n");
    }
   }