Java 9일차 ActionListener 테스트4 (버튼 2개의 경우)

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;

public class EventTest extends JFrame implements ActionListener
{
JTextArea ta;
JButton button_top, button_bot;

public EventTest()
{
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(400, 300);
this.setVisible(true);

ta = new JTextArea();

button_top = new JButton("클릭");
button_bot = new JButton("클릭");
button_top.addActionListener(this);
button_bot.addActionListener(this);

add(ta);
add("North", button_top);
add("South", button_bot);
}

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

public void actionPerformed(ActionEvent e)
{
Object source = e.getSource();

if(source==button_top)
ta.append("윗쪽 버튼"+'\n');
else if(source==button_bot)
ta.append("아래쪽 버튼"+'\n');
}
}