12：窗口监听

窗口监听：

package com.gui.lesson3;

import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestWindow {
    public static void main(String[] args) {
        new WindowFrame();
    }
}

class WindowFrame extends Frame {
    public WindowFrame() {
        setBackground(Color.green);
        setBounds(100, 100, 200, 200);
        setVisible(true);
        addWindowListener(new MyWindowListener());
    }

    //内部类
    //WindowListener要重写方法太多了，所以我们继承它的实现类，WindowAdapter，选择要重写的方法即可
    class MyWindowListener extends WindowAdapter {
        @Override
        public void windowClosing(WindowEvent e) {
            setVisible(false);//隐藏窗口
            //System.exit(0);//0是正常退出，1是关闭有异常的程序
        }
    }
}

测试两个常用的事件：

package com.gui.lesson3;

import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestWindow {
    public static void main(String[] args) {
        new WindowFrame();
    }
}

class WindowFrame extends Frame {
    public WindowFrame() {
        setBackground(Color.green);
        setBounds(100, 100, 200, 200);
        setVisible(true);
        addWindowListener(
                //推荐使用，匿名内部类
                new WindowAdapter() {
                    //关闭窗口
                    @Override
                    public void windowClosing(WindowEvent e) {
                        System.out.println("windowClosing");
                        System.exit(0);
                    }

                    //激活窗口：离开窗口后，会变成灰色，重新进入后，会显示正常的
                    @Override
                    public void windowActivated(WindowEvent e) {
                        WindowFrame source = (WindowFrame) e.getSource();
                        source.setTitle("人呢，快回来");
                        System.out.println("windowActivated");
                    }
                });
    }
}