import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.ArrayList;

public class MouseDraw extends JPanel implements MouseListener {
	private ArrayList<int[]> points;

	public MouseDraw() {
		setPreferredSize(new Dimension(150, 150));
		points = new ArrayList<>();
		addMouseListener(this); 
	}

	public void mouseClicked(MouseEvent e) {
		points.add(new int[] { e.getX(), e.getY() });
		repaint();
	}

	public void mouseEntered(MouseEvent e) {}
	public void mouseExited(MouseEvent e) {}
	public void mousePressed(MouseEvent e) {}
	public void mouseReleased(MouseEvent e) {}

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

		int i, n = points.size();
		for (i = 1; i < n; i++) {
			int[] p0 = points.get(i - 1);
			int[] p1 = points.get(i);
			g.drawLine(p0[0], p0[1], p1[0], p1[1]);
		}
	}

	public static void main(String[] args) {
		SwingUtilities.invokeLater(() -> {
			JFrame frame = new JFrame("Mouse Draw");
			frame.add(new MouseDraw());
			frame.pack();
			frame.setVisible(true);
			frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		});
	}
}