窗體監聽事件WindowListener

EXIT_ON_CLOSE：結束窗口所在的應用程序。在窗口被關閉的時候會退出JVM。

DISPOSE_ON_CLOSE：隱藏當前窗口，並釋放此窗體占有的資源。如果程序沒有其他線程在運行，當所有窗口都被dispose后，JVM也會退出。

舉例說明：關閉窗體A，窗體B也會退出。關閉窗體B，窗體A不會退出。

public class Demo{
    public static void main(String[] args){
        JFrame window1=new JFrame("窗體A");
        JFrame window2=new JFrame("窗體B");
        window1.setBounds(100,100,200,100);
        window2.setBounds(400,100,200,100);
        window1.setVisible(true);
        window2.setVisible(true);
        window1.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        window2.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    }
}

【窗體監聽事件 WindowListener】
windowOpened      打開
windowActivated   激活（獲得焦點狀態）
windowDeactivated 非激活（失去焦點狀態）
windowIconified   最小化
windowDeiconified 最小化恢復正常
windowClosing     關閉（右上角X），優先於windowClosed
windowClosed      關閉，DISPOSE_ON_CLOSE時才會被調用

public class Demo extends JFrame {
    public Demo() {
        setBounds(100, 100, 300, 300);
        setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        setVisible(true);
        addWindowListener(new MyWindowListener());//調用方法類對象
    }

    class MyWindowListener implements WindowListener {
        public void windowOpened(WindowEvent e) {
            System.out.println("窗體打開");
        }

        public void windowClosing(WindowEvent e) {
            System.out.println("窗體關閉exit");
        }

        public void windowClosed(WindowEvent e) {
            System.out.println("窗體關閉dispose");
        }

        public void windowIconified(WindowEvent e) {
            System.out.println("窗體最小化");
        }

        public void windowDeiconified(WindowEvent e) {
            System.out.println("窗體最小化恢復正常");
        }

        public void windowActivated(WindowEvent e) {
            System.out.println("窗體激活");
        }
        
        public void windowDeactivated(WindowEvent e) {
            System.out.println("窗體非激活");
        }
    }

    public static void main(String[] args) {
        new Demo();
    }
}