FocusAdapter類接收鍵盤焦點事件是一個抽象類（適配器）。這個類的所有方法都是空的。這個類是方便的類創建監聽器對象。

類聲明

以下是聲明 java.awt.event.FocusAdapter類：

public abstract class FocusAdapter
   extends Object
      implements FocusListener

類構造函數

S.N.	構造函數 & 描述
1	FocusAdapter()

類方法

S.N.	方法 & 描述
1	void focusGained(FocusEvent e)  Invoked when a component gains the keyboard focus.
2	focusLost(FocusEvent e)  Invoked when a component loses the keyboard focus.

方法繼承

這個類從以下類繼承的方法：

• java.lang.Object

FocusAdapter 例子

選擇使用任何編輯器創建以下java程序在 D:/ > SWING > com > yiibai > gui >

SwingAdapterDemo.java

package com.yiibai.gui;

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

public class SwingAdapterDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;

   public SwingAdapterDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      SwingAdapterDemo  swingAdapterDemo = new SwingAdapterDemo();        
      swingAdapterDemo.showFocusAdapterDemo();
   }

   private void prepareGUI(){
      mainFrame = new JFrame("Java SWING Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));

      headerLabel = new JLabel("",JLabel.CENTER );
      statusLabel = new JLabel("",JLabel.CENTER);        

      statusLabel.setSize(350,100);
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
	        System.exit(0);
         }        
      });    
      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showFocusAdapterDemo(){

      headerLabel.setText("Listener in action: FocusAdapter");      

      JButton okButton = new JButton("OK");
      JButton cancelButton = new JButton("Cancel");
      okButton.addFocusListener(new FocusAdapter(){
         public void focusGained(FocusEvent e) {
            statusLabel.setText(statusLabel.getText() 
            + e.getComponent().getClass().getSimpleName() 
            + " gained focus. ");
         }
      });  
      
      cancelButton.addFocusListener(new FocusAdapter(){
         public void focusLost(FocusEvent e) {
            statusLabel.setText(statusLabel.getText() 
            + e.getComponent().getClass().getSimpleName() 
            + " lost focus. ");
         }
      });  
      
      controlPanel.add(okButton);
      controlPanel.add(cancelButton);     
      mainFrame.setVisible(true);  
   }
}

編譯程序，使用命令提示符。到 D:/ > SWING 然後輸出以下命令。

D:SWING>javac comyiibaiguiSwingAdapterDemo.java

如果冇有錯誤出現，這意味著編譯成功。使用下麵的命令來運行程序。

D:SWING>java com.yiibai.gui.SwingAdapterDemo

驗證下麵的輸出