SE450: Serialing Unserializable Classes [48/86] Previous pageContentsNext page

file:horstmann/ch07_serial2/Car.java [source] [doc-public] [doc-private]
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package horstmann.ch07_serial2;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Ellipse2D;
import java.awt.geom.RectangularShape;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
   A serializable car shape.
 */
public class Car implements Serializable
{
  private static final long serialVersionUID = 2008L;
  /**
      Constructs a car.
      @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 Car(int x, int y, int width)
  {
    body = new Rectangle(x, y + width / 6,
        width - 1, width / 6);
    roof = new Rectangle(x + width / 3, y,
        width / 3, width / 6);
    frontTire = new Ellipse2D.Double(x + width / 6, y + width / 3,
        width / 6, width / 6);
    rearTire = new Ellipse2D.Double(x + width * 2 / 3, y + width / 3,
        width / 6, width / 6);
  }

  private void writeObject(ObjectOutputStream out)
      throws IOException
  {
    out.defaultWriteObject();
    writeRectangularShape(out, frontTire);
    writeRectangularShape(out, rearTire);
  }

  /**
      A helper method to write a rectangular shape.
      @param out the stream onto which to write the shape
      @param s the shape to write
   */
  private static void writeRectangularShape(ObjectOutputStream out,
      RectangularShape s)
          throws IOException
  {
    out.writeDouble(s.getX());
    out.writeDouble(s.getY());
    out.writeDouble(s.getWidth());
    out.writeDouble(s.getHeight());
  }

  private void readObject(ObjectInputStream in)
      throws IOException, ClassNotFoundException
  {
    in.defaultReadObject();
    frontTire = new Ellipse2D.Double();
    readRectangularShape(in, frontTire);
    rearTire = new Ellipse2D.Double();
    readRectangularShape(in, rearTire);
  }

  /**
      A helper method to read a rectangular shape.
      @param in the stream from which to read the shape
      @param s the shape to read. The method sets the frame
      of this rectangular shape.
   */
  private static void readRectangularShape(ObjectInputStream in,
      RectangularShape s)
          throws IOException
  {
    double x = in.readDouble();
    double y = in.readDouble();
    double width = in.readDouble();
    double height = in.readDouble();
    s.setFrame(x, y, width, height);
  }

  /**
      Draws the car.
      @param g2 the graphics context
   */
  public void draw(Graphics2D g2)
  {
    g2.draw(body);
    g2.draw(roof);
    g2.draw(frontTire);
    g2.draw(rearTire);
  }

  public String toString()
  {
    return getClass().getName()
        + "[body=" + body
        + ",roof=" + roof
        + ",frontTire=" + formatRectangularShape(frontTire)
        + ",rearTire=" + formatRectangularShape(rearTire)
        + "]";
  }

  /**
      A helper method to format a rectangular shape.
      @param s the shape to format
      @return a formatted representation of the given shape
   */
  private static String formatRectangularShape(RectangularShape s)
  {
    return RectangularShape.class.getName()
        + "[x=" + s.getX()
        + ",y=" + s.getY()
        + ",width=" + s.getWidth()
        + ",height=" + s.getHeight()
        + "]";
  }


  private Rectangle body;
  private Rectangle roof;
  private transient Ellipse2D.Double frontTire;
  private transient Ellipse2D.Double rearTire;
}


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