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

public class SketchPad extends Component {

    final int SIZE = 600;

    Label status = new Label("Welcome to SketchPad!");
    Point target = new Point(SIZE/2, SIZE/2);
    ArrayList<Point> points = new ArrayList<Point>();

    public SketchPad(Container pane) {
        setPreferredSize(new Dimension(SIZE, SIZE));
        pane.setLayout(new BorderLayout());
        pane.add(this, BorderLayout.CENTER);
        pane.add(status, BorderLayout.SOUTH);
        addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
                status.setText("Click at " + e.getPoint());
                target = e.getPoint();
                repaint();
            }

            @Override
            public void mousePressed(MouseEvent e) {
            }

            @Override
            public void mouseReleased(MouseEvent e) {
            }

            @Override
            public void mouseEntered(MouseEvent e) {
            }

            @Override
            public void mouseExited(MouseEvent e) {
            }
        });
        addMouseMotionListener(new MouseMotionListener() {
            @Override
            public void mouseDragged(MouseEvent e) {
            }

            @Override
            public void mouseMoved(MouseEvent e) {
            }
        });
    }

    public void paint(Graphics g) {
        // An example of how to draw:
        g.drawLine(0, 0, target.x, target.y);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame("sketch");
        SketchPad st = new SketchPad(f.getContentPane());
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
    }
}