import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import javax.swing.*;

/**
   A program that allows users to move a car with the mouse.
*/
public class CarMover extends JApplet
{
    public CarPanel panel;
    public void init() {
	panel = new CarPanel();
	getContentPane().add(panel);
    }
    
    public void start() {
    }
    public void stop() {
    }
    
    
   public static void main(String[] args)
   {
       final int FRAME_WIDTH = 400;
       final int FRAME_HEIGHT = 400;
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      Container contentPane = frame.getContentPane();
      contentPane.add(new CarPanel());
      frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
      frame.setVisible(true);
   }
   
}

CarPanel.java

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

/**
   A panel that shows a scene composed of items.
*/
public class CarPanel extends JPanel
{
   public CarPanel()
   {
      car = new CarShape(20, 20, 50);
      addMouseListener(new
         MouseAdapter()
         {
            public void mousePressed(MouseEvent event)
            {
               mousePoint = event.getPoint();
               if (!car.contains(mousePoint))
                  mousePoint = null;
            }
         });

      addMouseMotionListener(new
         MouseMotionAdapter()
         {
            public void mouseDragged(MouseEvent event)
            {
               if (mousePoint == null) return;
               Point lastMousePoint = mousePoint;
               mousePoint = event.getPoint();

               car.translate(
                  mousePoint.getX() - lastMousePoint.getX(),
                  mousePoint.getY() - lastMousePoint.getY());
               repaint();
            }
         });
   }

   public void paintComponent(Graphics g)
   {
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D) g;
      car.draw(g2);
   }

   private CarShape car;
   private Point mousePoint;
}                               

CarShape.java

import java.awt.*;
import java.awt.geom.*;

/**
   A car shape.
*/
public class CarShape
{
   /**
      Constructs a car shape.
      @param x the left of the bounding rectangle
      @param y the top of the bounding rectangle
      @param width the width of the bounding rectangle
   */
   public CarShape(int x, int y, int width)
   {
      this.x = x;
      this.y = y;
      this.width = width;
   }

   public void draw(Graphics2D g2)
   {
      Rectangle2D.Double body
         = new Rectangle2D.Double(x, y + width / 6, 
            width - 1, width / 6);
      Ellipse2D.Double frontTire
         = new Ellipse2D.Double(x + width / 6, y + width / 3, 
            width / 6, width / 6);
      Ellipse2D.Double rearTire
         = new Ellipse2D.Double(x + width * 2 / 3, 
            y + width / 3,
            width / 6, width / 6);

      // the bottom of the front windshield
      Point2D.Double r1
         = new Point2D.Double(x + width / 6, y + width / 6);
      // the front of the roof
      Point2D.Double r2
         = new Point2D.Double(x + width / 3, y);
      // the rear of the roof
      Point2D.Double r3
         = new Point2D.Double(x + width * 2 / 3, y);
      // the bottom of the rear windshield
      Point2D.Double r4
         = new Point2D.Double(x + width * 5 / 6, y + width / 6);
      Line2D.Double frontWindshield
         = new Line2D.Double(r1, r2);
      Line2D.Double roofTop
         = new Line2D.Double(r2, r3);
      Line2D.Double rearWindshield
         = new Line2D.Double(r3, r4);

      g2.draw(body);
      g2.draw(frontTire);
      g2.draw(rearTire);
      g2.draw(frontWindshield);
      g2.draw(roofTop);
      g2.draw(rearWindshield);
   }
   
   public boolean contains(Point2D p)
   {
      return x <= p.getX() && p.getX() <= x + width 
         && y <= p.getY() && p.getY() <= y + width / 2;
   }

   public void translate(double dx, double dy)
   {
      x += dx;
      y += dy;
   }

   private int x;
   private int y;
   private int width;
}