ActionListener Event Source In Java ActionPerformed Method

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

public class JavaEventSourceExample extends JFrame implements ActionListener {

	private JButton button1 = new JButton("Click Me!");
	private int clickCount = 0;

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

	public JavaEventSourceExample() {
		this.setSize(200, 100);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setTitle("I'm Listening");

		JPanel panel1 = new JPanel();
		button1.addActionListener(this);
		panel1.add(button1);
		this.add(panel1);

		this.setVisible(true);
	}

	public void actionPerformed(ActionEvent e) {
		if (e.getSource() == button1) {
			clickCount++;
			if (clickCount == 1)
				button1.setText("I've been clicked!");
			else
				button1.setText("I've been clicked" + clickCount + " times!");
		}
	}
}
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