java例程练习（事件监听机制）

//事件监听机制

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

public class TestEvent {
    public static void main(String[] args) {
    	Frame f = new Frame("Test");
    	Button b = new Button("Press Me!");

    	Monitor bh = new Monitor(); //实现了某种监听器接口的类的对象

    	b.addActionListener(bh);    //注册

    	f.add(b, BorderLayout.CENTER);
    	f.pack();
    	f.setVisible(true);
    }
}

//实现了某种监听器接口的类
class Monitor implements ActionListener {
	public void actionPerformed(ActionEvent e) {
		System.out.println("A button has been pressed");
	}
}

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

public class TestActionEvent {
	public static void main(String[] args) {
		Frame f = new Frame("Test");
		Button b1 = new Button("Start");
		Button b2 = new Button("Stop");

		//一个监听器类被两个button监听
		Monitor2 bh = new Monitor2();
		b1.addActionListener(bh);
		b2.addActionListener(bh);

		b2.setActionCommand("Game over");

		f.add(b1,"North");
		f.add(b2,"Center");
		f.pack();

		f.setVisible(true);

	}

}

class Monitor2 implements ActionListener {
	public void actionPerformed (ActionEvent e) {
		System.out.println("A button has been pressed," +
			"the relative info is:\n" + e.getActionCommand());
	}
}