AVAJAVA Web Tutorials

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Animal is an abstract class with the makeSound() abstract method. Subclasses of Animal implement the makeSound() method.

Animal.java

package com.cakes.animals;

public abstract class Animal {
	public abstract String makeSound();
}

The Cat class is shown here.

Cat.java

package com.cakes.animals;

public class Cat extends Animal {

	@Override
	public String makeSound() {
		return "Meow";
	}

}

The Dog class is shown here.

Dog.java

package com.cakes.animals;

public class Dog extends Animal {

	@Override
	public String makeSound() {
		return "Woof";
	}

}

The Snake class is shown here.

Snake.java

package com.cakes.animals;

public class Snake extends Animal {

	@Override
	public String makeSound() {
		return "Hiss";
	}

}

The Tyrannosaurus class is shown here.

Tyrannosaurus.java

package com.cakes.animals;

public class Tyrannosaurus extends Animal {

	@Override
	public String makeSound() {
		return "Roar";
	}

}

The Demo class contains our main() method. It creates an AbstractFactory object. From the AbstractFactory, we obtain a SpeciesFactory (a ReptileFactory) and get two Animal objects (Tyrannosaurus and Snake) from the SpeciesFactory. After this, we obtain another SpeciesFactory (a MammalFactory) and then obtain two more Animal objects (Dog and Cat).

Demo.java

package com.cakes;

import com.cakes.animals.Animal;

public class Demo {

	public static void main(String[] args) {
		AbstractFactory abstractFactory = new AbstractFactory();

		SpeciesFactory speciesFactory1 = abstractFactory.getSpeciesFactory("reptile");
		Animal a1 = speciesFactory1.getAnimal("tyrannosaurus");
		System.out.println("a1 sound: " + a1.makeSound());
		Animal a2 = speciesFactory1.getAnimal("snake");
		System.out.println("a2 sound: " + a2.makeSound());

		SpeciesFactory speciesFactory2 = abstractFactory.getSpeciesFactory("mammal");
		Animal a3 = speciesFactory2.getAnimal("dog");
		System.out.println("a3 sound: " + a3.makeSound());
		Animal a4 = speciesFactory2.getAnimal("cat");
		System.out.println("a4 sound: " + a4.makeSound());

	}

}

Executing the Demo class displays the sounds made by the four Animal objects. The console output is shown here.

Console Output

a1 sound: Roar
a2 sound: Hiss
a3 sound: Woof
a4 sound: Meow

Notice the use of polymorphism. We obtain different factories via the common SpeciesFactory superclass. We also obtain different animals via the common Animal superclass.