Abstract Factory

Abstract Factory patterns work around a super-factory which creates other factories. This factory is also called as factory of factories. This type of design pattern comes under creational pattern as this pattern provides one of the best ways to create an object.

In Abstract Factory pattern an interface is responsible for creating a factory of related objects without explicitly specifying their classes. Each generated factory can give the objects as per the Factory pattern.


Abstract Factory in Java recognizable by creational methods returning the factory itself which in turn can be used to create another abstract/interface type

• javax.xml.parsers.DocumentBuilderFactory#newInstance()
• javax.xml.transform.TransformerFactory#newInstance()
• javax.xml.xpath.XPathFactory#newInstance()

public interface Shape {
   void draw();
}

public class Rectangle implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Rectangle::draw() method.");
   }
}

public class Square implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Square::draw() method.");
   }
}

public class Circle implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Circle::draw() method.");
   }
}

public interface Color {
   void fill();
}

public class Red implements Color {

   @Override
   public void fill() {
      System.out.println("Inside Red::fill() method.");
   }
}

public class Green implements Color {

   @Override
   public void fill() {
      System.out.println("Inside Green::fill() method.");
   }
}

public class Blue implements Color {

   @Override
   public void fill() {
      System.out.println("Inside Blue::fill() method.");
   }
}

public abstract class AbstractFactory {
   abstract Color getColor(String color);
   abstract Shape getShape(String shape) ;
}

public class ShapeFactory extends AbstractFactory {
	
   @Override
   public Shape getShape(String shapeType){
   
      if(shapeType == null){
         return null;
      }		
      
      if(shapeType.equalsIgnoreCase("CIRCLE")){
         return new Circle();
         
      }else if(shapeType.equalsIgnoreCase("RECTANGLE")){
         return new Rectangle();
         
      }else if(shapeType.equalsIgnoreCase("SQUARE")){
         return new Square();
      }
      
      return null;
   }
   
   @Override
   Color getColor(String color) {
      return null;
   }
}

public class ColorFactory extends AbstractFactory {
	
   @Override
   public Shape getShape(String shapeType){
      return null;
   }
   
   @Override
   Color getColor(String color) {
   
      if(color == null){
         return null;
      }		
      
      if(color.equalsIgnoreCase("RED")){
         return new Red();
         
      }else if(color.equalsIgnoreCase("GREEN")){
         return new Green();
         
      }else if(color.equalsIgnoreCase("BLUE")){
         return new Blue();
      }
      
      return null;
   }
}

public class FactoryProducer {
   public static AbstractFactory getFactory(String choice){
   
      if(choice.equalsIgnoreCase("SHAPE")){
         return new ShapeFactory();
         
      }else if(choice.equalsIgnoreCase("COLOR")){
         return new ColorFactory();
      }
      
      return null;
   }
}

public class AbstractFactoryPatternDemo {
   public static void main(String[] args) {

      //get shape factory
      AbstractFactory shapeFactory = FactoryProducer.getFactory("SHAPE");

      //get an object of Shape Circle
      Shape shape1 = shapeFactory.getShape("CIRCLE");

      //call draw method of Shape Circle
      shape1.draw();

      //get an object of Shape Rectangle
      Shape shape2 = shapeFactory.getShape("RECTANGLE");

      //call draw method of Shape Rectangle
      shape2.draw();
      
      //get an object of Shape Square 
      Shape shape3 = shapeFactory.getShape("SQUARE");

      //call draw method of Shape Square
      shape3.draw();

      //get color factory
      AbstractFactory colorFactory = FactoryProducer.getFactory("COLOR");

      //get an object of Color Red
      Color color1 = colorFactory.getColor("RED");

      //call fill method of Red
      color1.fill();

      //get an object of Color Green
      Color color2 = colorFactory.getColor("Green");

      //call fill method of Green
      color2.fill();

      //get an object of Color Blue
      Color color3 = colorFactory.getColor("BLUE");

      //call fill method of Color Blue
      color3.fill();
   }
}