ActionEvent2_GUI視窗程式

//https://www.facebook.com/groups/1403852566495675/permalink/2397128547168067/
package com.sample;

import java.awt.Button;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class ActionEvent2 {
    private static Frame frame = new Frame();
    private static Action action = new Action();
    private static Button btn1 = new Button("Blue");
    private static Button btn2 = new Button("Green");
    private static Button btn3 = new Button("Red");
    private static Button btn4 = new Button("Exit");

    public static void main(String args[]) {
        btn1.addActionListener(action);
        btn2.addActionListener(action);
        btn3.addActionListener(action);
        btn4.addActionListener(action);

        frame.setTitle("Action Event");
        frame.setLayout(new FlowLayout(FlowLayout.LEFT));
        frame.setSize(400, 250);
        frame.setLocation(350, 250);
        frame.add(btn1);
        frame.add(btn2);
        frame.add(btn3);
        frame.add(btn4);
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.setVisible(true);
    }

    private static class Action implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            Button button = (Button) e.getSource();
            if (button == btn1) {
                frame.setBackground(Color.blue);
            } else if (button == btn2) {
                frame.setBackground(Color.green);
            } else if (button == btn3) {
                frame.setBackground(Color.red);
            } else {
                System.exit(0);
            }
        }
    }
}