import java.awt.*;
import java.awt.event.*;			// for ActionListener
import javax.swing.*;

public class SimpleButtonExample	// to demonstrate the use of JButtons
{
	public static void main(String[] args)
	{
		JFrame frame=new JFrame("simple button example");
		frame.setSize(300,200);
		ButtonExample p=new ButtonExample();
		frame.add(p);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}
	
	public static class ButtonExample extends JPanel implements ActionListener		// ActionListener for JButtons
	{
		private JButton b1, b2, b3, clear, quit;		// 5 JButtons, first three display a new message, fourth clears message, fifth quits
		private JLabel lab;								// for output of the message
		
		public ButtonExample()
		{
			b1=new JButton("button 1");					// instantiate the 5 JButtons and JLabel
			b2=new JButton("button 2");	
			b3=new JButton("button 3");
			clear=new JButton("clear");
			quit=new JButton("quit");
			lab=new JLabel("               ");
			b1.addActionListener(this);					// use this class to implement the ActionListener for all 5 JButtons
			b2.addActionListener(this);
			b3.addActionListener(this);
			clear.addActionListener(this);
			quit.addActionListener(this);
			JPanel p1=new JPanel(new GridLayout(3,2));	// place the 5 JButtons and JLabel in a 3x2 grid
			p1.add(b1);
			p1.add(b2);
			p1.add(b3);
			p1.add(clear);
			p1.add(quit);
			p1.add(lab);
			add(p1);									// place the 3x2 grid in this JPanel
		}
		
		public void actionPerformed(ActionEvent e)		// will be called whenever a JButton is clicked
		{
			if(e.getSource()==quit) System.exit(0);		// exit the program if the button is quit
			else {										// otherwise set text to be the message needed for each JButton where
				String text="";							//    the clear JButton causes the text to be empty
				if(e.getSource()==b1) text="Button 1 registered";
				if(e.getSource()==b2) text="Button 2 registered";
				if(e.getSource()==b3) text="Button 3 registered";
				if(e.getSource()==clear) text="                   ";
				lab.setText(text);						// place the new text into the JLabel
			}
		}
	}
}