learning java AWT widowEvent and MouseEvent

import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

public class WindowListenerTest {

    private Frame f = new Frame();
    private TextArea ta = new TextArea(,);
    private Button bt  = new Button("bt");
    public void init(){
        f.addWindowListener(new MyListener());
        bt.addMouseListener(new MyMouseListener());
        f.add(bt,BorderLayout.NORTH);
        f.add(ta);
        f.pack();
        f.setVisible(true);
    }
    class MyListener  implements WindowListener{
        public void windowOpened(WindowEvent e){
            ta.append("window first be opened" +  "\n");
        }

        public void windowClosed(WindowEvent e){
            ta.append("window closed " + "\n");
            System.exit();
        }

        public void windowClosing(WindowEvent e){
            ta.append("window close by x" + "\n");
            System.exit();
        }

        public void windowIconified(WindowEvent e){
            ta.append("window iconified be trigger" + "\n");
        }
        public void windowDeiconified(WindowEvent e){
            ta.append("window deiconified be trigger" + "\n");
        }

        public void windowActivated(WindowEvent e){
            ta.append("window activated be trigger" + "\n");
        }

        public void windowDeactivated(WindowEvent e){
            ta.append("window deactivated be trigger" + "\n");
        }

    };

    class MyMouseListener implements MouseListener{
        public void mouseEntered(MouseEvent event){
            System.out.println("mouseEntered");
        }

        public void mouseExited(MouseEvent event){
            System.out.println("mouseExited");
        }
        public void mouseClicked(MouseEvent event){
            System.out.println("mouseClicked");
        }
        public void mousePressed(MouseEvent event){
            System.out.println("mousePressed");
        }
        public void mouseReleased(MouseEvent event){
            System.out.println("mouseReleased");
        }

    }

    public static void main(String[] args) {
        new WindowListenerTest().init();
    }
}

output: