Only parent class is Serializable : Object Serialization « File « Java Tutorial

1. Java Tutorial
2. File
3. Object Serialization

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

abstract class Shape implements Serializable {
  public static final int RED = 1, BLUE = 2, GREEN = 3;

  private int x, y, size;

  private static Random r = new Random();

  private static int counter = 0;

  public abstract void setColor(int newColor);

  public abstract int getColor();

  public Shape(int xVal, int yVal, int dim) {
    x = xVal;
    y = yVal;
    size = dim;
  }

  public String toString() {
    return getClass() + "color[" + getColor() + "] xPos[" + x + "] yPos[" + y + "] dim[" + size
        + "]\n";
  }

}

class Circle extends Shape {
  private static int color = RED;

  public Circle(int xVal, int yVal, int dim) {
    super(xVal, yVal, dim);
  }

  public void setColor(int newColor) {
    color = newColor;
  }

  public int getColor() {
    return color;
  }
}

class Square extends Shape {
  private static int color;

  public Square(int xVal, int yVal, int dim) {
    super(xVal, yVal, dim);
    color = RED;
  }

  public void setColor(int newColor) {
    color = newColor;
  }

  public int getColor() {
    return color;
  }
}

class Line extends Shape {
  private static int color = RED;

  public static void serializeStaticState(ObjectOutputStream os) throws IOException {
    os.writeInt(color);
  }

  public static void deserializeStaticState(ObjectInputStream os) throws IOException {
    color = os.readInt();
  }

  public Line(int xVal, int yVal, int dim) {
    super(xVal, yVal, dim);
  }

  public void setColor(int newColor) {
    color = newColor;
  }

  public int getColor() {
    return color;
  }
}

public class MainClass {
  public static void main(String[] args) throws Exception {
    List shapeTypes, shapes;
    if (args.length == 0) {
      shapeTypes = new ArrayList();
      shapes = new ArrayList();

      shapeTypes.add(Circle.class);
      shapeTypes.add(Square.class);
      shapeTypes.add(Line.class);

      shapes.add(new Square(4, 3, 200));
      shapes.add(new Circle(1, 2, 100));
      shapes.add(new Line(1, 2, 100));

      ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("CADState.out"));
      out.writeObject(shapeTypes);
      Line.serializeStaticState(out);
      out.writeObject(shapes);
    } else {
      ObjectInputStream in = new ObjectInputStream(new FileInputStream(args[0]));
      shapeTypes = (List) in.readObject();
      Line.deserializeStaticState(in);
      shapes = (List) in.readObject();
    }

    System.out.println(shapes);
  }

}
/*
*/

[class Squarecolor[1] xPos[4] yPos[3] dim[200]
, class Circlecolor[1] xPos[1] yPos[2] dim[100]
, class Linecolor[1] xPos[1] yPos[2] dim[100]
]