Java从入门到精通阅读笔记（第4版）17

13.9.3焦点事件监听

package com.lzw;

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class FocusEventTest extends JFrame{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	public FocusEventTest() {
		setSize(250,100);
		setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
		Container cp=getContentPane();
		getContentPane().setLayout(new FlowLayout());

		final JLabel label = new JLabel();
		getContentPane().add(label);
		JTextField jt=new JTextField("请单击其他文本框",10);
		JTextField jt2=new JTextField("请单击我",10);
		cp.add(jt);
		cp.add(jt2);
		jt.addFocusListener(new FocusListener(){
			//组件失去焦点时调用的方法 
			public void focusLost(FocusEvent arg0) {
				JOptionPane.showMessageDialog(null, "文本框失去焦点");
			}
			//组件获取键盘焦点时调用的方法
			public void focusGained(FocusEvent arg0) {
			}
		});
		setVisible(true);
	}
	public static void main(String[] args) {
		new FocusEventTest();
	}

}