carfield.com.hk

Games.java

2001-12-26T16:00:00Z

//: c05:Games.java
// An example of the Abstract Factory pattern.
import com.bruceeckel.test.*;

interface Obstacle {
  void action();
}

interface Player {
  void interactWith(Obstacle o);
}

class Kitty implements Player {
  public void interactWith(Obstacle ob) {
    System.out.print("Kitty has encountered a ");
    ob.action();
  }
}

class KungFuGuy implements Player {
  public void interactWith(Obstacle ob) {
    System.out.print("KungFuGuy now battles a ");
    ob.action();
  }
}

class Puzzle implements Obstacle {
  public void action() { 
    System.out.println("Puzzle"); 
  }
}

class NastyWeapon implements Obstacle {
  public void action() { 
    System.out.println("NastyWeapon"); 
  }
}

// The Abstract Factory:
interface GameElementFactory {
  Player makePlayer();
  Obstacle makeObstacle();
}

// Concrete factories:
class KittiesAndPuzzles 
implements GameElementFactory {
  public Player makePlayer() { 
    return new Kitty();
  }
  public Obstacle makeObstacle() {
    return new Puzzle();
  }
}

class KillAndDismember 
implements GameElementFactory {
  public Player makePlayer() { 
    return new KungFuGuy();
  }
  public Obstacle makeObstacle() {
    return new NastyWeapon();
  }
}

class GameEnvironment {
  private GameElementFactory gef;
  private Player p;
  private Obstacle ob;
  public GameEnvironment(
    GameElementFactory factory) {
    gef = factory;
    p = factory.makePlayer(); 
    ob = factory.makeObstacle();
  }
  public void play() { p.interactWith(ob); }
}

public class Games extends UnitTest {
  GameElementFactory
    kp = new KittiesAndPuzzles(),
    kd = new KillAndDismember();
  GameEnvironment 
    g1 = new GameEnvironment(kp),
    g2 = new GameEnvironment(kd);
  // These just ensure no exceptions are thrown:
  public void test1() { g1.play(); }
  public void test2() { g2.play(); }
  public static void main(String args[]) {
    Games g = new Games();
    g.test1();
    g.test2();
  }
} ///:~

ShapeFactory1.java

2001-12-26T16:00:00Z

//: c05:shapefact1:ShapeFactory1.java
// A simple static factory method.
package c05.shapefact1;
import java.util.*;
import com.bruceeckel.test.*;

abstract class Shape {
  public abstract void draw();
  public abstract void erase();
  public static Shape factory(String type) {
    if(type.equals("Circle")) return new Circle();
    if(type.equals("Square")) return new Square();
    throw new RuntimeException(
      "Bad shape creation: " + type);
  }
}

class Circle extends Shape {
  Circle() {} // Friendly constructor
  public void draw() { 
    System.out.println("Circle.draw"); 
  }
  public void erase() { 
    System.out.println("Circle.erase"); 
  }
}

class Square extends Shape {
  Square() {} // Friendly constructor
  public void draw() { 
    System.out.println("Square.draw"); 
  }
  public void erase() { 
    System.out.println("Square.erase"); 
  }
}

public class ShapeFactory1 extends UnitTest {
  String shlist[] = { "Circle", "Square", 
    "Square", "Circle", "Circle", "Square" };
  List shapes = new ArrayList();
  public void test() {
    for(int i = 0; i < shlist.length; i++)
      shapes.add(Shape.factory(shlist[i]));
    Iterator i = shapes.iterator();
    while(i.hasNext()) {
      Shape s = (Shape)i.next();
      s.draw();
      s.erase();
    }
  }
  public static void main(String args[]) {
    new ShapeFactory1().test();
  }
} ///:~

ShapeFactory2.java

2001-12-26T16:00:00Z

//: c05:shapefact2:ShapeFactory2.java
// Polymorphic factory methods.
package c05.shapefact2;
import java.util.*;
import com.bruceeckel.test.*;

interface Shape {
  void draw();
  void erase();
}

abstract class ShapeFactory {
  protected abstract Shape create();
  private static Map factories = new HashMap();
  public static void 
  addFactory(String id, ShapeFactory f) {
    factories.put(id, f);
  }
  // A Template Method:
  public static final 
  Shape createShape(String id) {
    if(!factories.containsKey(id)) {
      try {
        // Load dynamically
        Class.forName("c05.shapefact2." + id);
      } catch(ClassNotFoundException e) {
        throw new RuntimeException(
          "Bad shape creation: " + id);
      }
      // See if it was put in:
      if(!factories.containsKey(id))
        throw new RuntimeException(
          "Bad shape creation: " + id);
    }
    return 
      ((ShapeFactory)factories.get(id)).create();
  }
}

class Circle implements Shape {
  private Circle() {}
  public void draw() { 
    System.out.println("Circle.draw"); 
  }
  public void erase() { 
    System.out.println("Circle.erase");
  }
  private static class Factory 
  extends ShapeFactory {
    protected Shape create() { 
      return new Circle(); 
    }
  }
  static {
    ShapeFactory.addFactory(
      "Circle", new Factory());
  }
}

class Square implements Shape {
  private Square() {} 
  public void draw() { 
    System.out.println("Square.draw"); 
  }
  public void erase() { 
    System.out.println("Square.erase"); 
  }
  private static class Factory 
  extends ShapeFactory {
    protected Shape create() { 
      return new Square(); 
    }
  }
  static {
    ShapeFactory.addFactory(
      "Square", new Factory());
  }
}

public class ShapeFactory2 extends UnitTest {
  String shlist[] = { "Circle", "Square", 
    "Square", "Circle", "Circle", "Square" };
  List shapes = new ArrayList();
  public void test() {
    // This just makes sure it will complete 
    // without throwing an exception.
    for(int i = 0; i < shlist.length; i++)
      shapes.add(
        ShapeFactory.createShape(shlist[i]));
    Iterator i = shapes.iterator();
    while(i.hasNext()) {
      Shape s = (Shape)i.next();
      s.draw();
      s.erase();
    }
  }
  public static void main(String args[]) {
    new ShapeFactory2().test();
  }
} ///:~

makefile

2001-12-26T16:00:00Z