import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class MyPanel extends JPanel {
	private int x = -1;
	private int y = -1;

	public MyPanel(LayoutManager layout) {
		super(layout);

		// anonymouse listener
		addMouseListener(new MouseAdapter() {
			@Override
			public void mouseClicked(MouseEvent e) {
				// left clicked
				if (e.getButton() == MouseEvent.BUTTON1) {
					System.out.println("Left button clicked at " + e.getX() + "," + e.getY());
				}
				x = e.getX();
				y = e.getY();
				repaint();
			}
		});
	}

	@Override
	protected void paintComponent(Graphics g) {
		super.paintComponent(g);

		// red dot
		g.setColor(Color.RED);
		g.drawRect(x, y, 1, 1);
	}

}