Mega Code Archive
Saving and restoring the state of a pretend CAD system
<![CDATA[
// : c12:CADState.java
// Saving and restoring the state of a pretend CAD system.
// {Clean: CADState.out}
//package c12;
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
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 xPos, yPos, dimension;
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) {
xPos = xVal;
yPos = yVal;
dimension = dim;
}
public String toString() {
return getClass() + "color[" + getColor() + "] xPos[" + xPos
+ "] yPos[" + yPos + "] dim[" + dimension + "]\n";
}
public static Shape randomFactory() {
int xVal = r.nextInt(100);
int yVal = r.nextInt(100);
int dim = r.nextInt(100);
switch (counter++ % 3) {
default:
case 0:
return new Circle(xVal, yVal, dim);
case 1:
return new Square(xVal, yVal, dim);
case 2:
return new Line(xVal, yVal, dim);
}
}
}
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 CADState {
public static void main(String[] args) throws Exception {
List shapeTypes, shapes;
if (args.length == 0) {
shapeTypes = new ArrayList();
shapes = new ArrayList();
// Add references to the class objects:
shapeTypes.add(Circle.class);
shapeTypes.add(Square.class);
shapeTypes.add(Line.class);
// Make some shapes:
for (int i = 0; i < 10; i++)
shapes.add(Shape.randomFactory());
// Set all the static colors to GREEN:
for (int i = 0; i < 10; i++)
((Shape) shapes.get(i)).setColor(Shape.GREEN);
// Save the state vector:
ObjectOutputStream out = new ObjectOutputStream(
new FileOutputStream("CADState.out"));
out.writeObject(shapeTypes);
Line.serializeStaticState(out);
out.writeObject(shapes);
} else { // There's a command-line argument
ObjectInputStream in = new ObjectInputStream(new FileInputStream(
args[0]));
// Read in the same order they were written:
shapeTypes = (List) in.readObject();
Line.deserializeStaticState(in);
shapes = (List) in.readObject();
}
// Display the shapes:
System.out.println(shapes);
}
} ///:~
]]>