Java factory pattern example

Factory pattern is to encapsulate object creation into a method so every time when you creating a new instance of the object you call this method. It standards the object creation and avoids mistakes might have made if you are creating the object yourself.

Animal.java

public interface Animal {
    void talk();
}

Dog.java

public class Dog implements Animal {
    @Override
    public void talk() {
    	System.out.println("Woof...");
    }
}

Cat.java

public class Cat implements Animal {
    @Override
    public void talk() {
    	System.out.println("Meow...");
    }
}

AnimalFactory.java

public class AnimalFactory {
    
    public Animal getAnimal(String animal) {
        if (animal.isEmpty()) return null;
        
        if (animal.equalsIgnoreCase("Dog")) return new Dog();
        else if (animal.equalsIgnoreCase("Cat")) return new Cat();
        else return null;
    }
    
}

FactoryPattern.java, the getAnimal() is the factory method which creates the object for you according to the string you passed in.

public class FactoryPattern {
	public static void main(String[] args) {
	    AnimalFactory animalFactory= new AnimalFactory();
	    
	    Animal dog = animalFactory.getAnimal("Dog");
	    dog.talk();
	    
	    Animal cat = animalFactory.getAnimal("Cat");
	    cat.talk();
	}	
}

output:

Woof...
Meow...