package Collection;

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.EventQueue;

import java.awt.Font;

import java.awt.event.WindowEvent;

import java.awt.event.WindowFocusListener;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

public class Windowfa extends JFrame{

     private JPanel contentPane;

     private JLabel lblTip;

     private JLabel lblTight;//声明窗体中的组件

public static void main(String[] args) {

EventQueue.invokeLater(new Runnable(){

public void run(){

try{

Windowfa frame = new Windowfa();

frame.setVisible(true);

}catch(Exception e){

e.printStackTrace();

}

}

});

}

public  Windowfa(){

setResizable(false);

setTitle("焦点事件监听");

setDefaultCloseOperation(EXIT_ON_CLOSE);

setBounds(100, 100, 200, 200);

contentPane=new JPanel();

contentPane.setBackground(Color.YELLOW);

contentPane.setLayout(new BorderLayout(0,0));

contentPane.setBorder(new EmptyBorder(5, 5, 5,5));

setContentPane(contentPane);

lblTip=new JLabel("JFabel 窗体获得焦点，灯亮了");

lblTip.setForeground(Color.cyan);

lblTip.setFont(new Font("微软雅黑",Font.PLAIN,14));

lblTip.setHorizontalAlignment(SwingConstants.CENTER);

contentPane.add(lblTip,BorderLayout.NORTH);

lblTight=new JLabel();

lblTight.setHorizontalAlignment(SwingConstants.CENTER);

lblTight.setIcon(new ImageIcon(Windowfa.class.getResource("dengliang.png")));

contentPane.add(lblTight,BorderLayout.SOUTH);

addWindowFocusListener(new WindowFocusListener() {

public void windowLostFocus(WindowEvent e) {

lblTight.setIcon(new ImageIcon(Windowfa.class.getResource("dengmie.png")));

lblTip.setText("JFabel 窗体失去焦点，灯灭了");

}

public void windowGainedFocus(WindowEvent e) {

lblTight.setIcon(new ImageIcon(Windowfa.class.getResource("dengliang.png")));

lblTip.setText("JFabel 窗体获得焦点，灯亮了");

}

});

}

}

1、问题：WindowFocusListene中为什么需要run()方法，起什么作用。又为什么需要try....catch 语句。

public static void main(String[] args) {

EventQueue.invokeLater(new Runnable(){

public void run(){

try{

Windowfa frame = new Windowfa();

frame.setVisible(true);

}catch(Exception e){

e.printStackTrace();

}

}

});

}

2、WindowFocusListene中 失去焦点后，需要由弹出窗口说明“程序暂停”等字样的窗体  老师求教。