Java by API/java.awt.event/MouseListener

implements MouseListener

import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainClass {
  public static void main(String[] args) {
    JFrame aWindow = new JFrame();
    aWindow.setBounds(200, 200, 200, 200);
    aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container content = aWindow.getContentPane();
    content.add(new MouseMotionEvents());
    aWindow.setVisible(true);
  }
}
class MouseMotionEvents extends JPanel implements MouseListener,
    MouseMotionListener {
  Point p;
  public MouseMotionEvents() {
    addMouseListener(this);
    addMouseMotionListener(this);
  }
  public void mouseClicked(MouseEvent me) {
  }
  public void mouseEntered(MouseEvent me) {
  }
  public void mouseExited(MouseEvent me) {
  }
  public void mousePressed(MouseEvent me) {
    p = me.getPoint();
    repaint();
  }
  public void mouseReleased(MouseEvent me) {
    p = null;
    repaint();
  }
  public void mouseDragged(MouseEvent me) {
    p = me.getPoint();
    repaint();
  }
  public void mouseMoved(MouseEvent me) {
  }
  public void paint(Graphics g) {
    if (p != null) {
      Dimension d = getSize();
      int xc = d.width / 2;
      int yc = d.height / 2;
      g.drawLine(xc, yc, p.x, p.y);
    }
  }
}