Creational Design Patterns - 3- Factory Method Design Pattern

A factory method Pattern is a creational pattern. it is used to instantiate object from one among a set of classes based on a logic.

Say that we have set of classes which extend common super class or interface .

Now , you will create class with a method which accept argument. this method is our factory method . based on the arguments passed to factory method does logical operations and decide on which sub class to instantiate .

Info : The method newInstance() is the factory method which instantiates the sax parsers based on some predefined logic .

Lets do sample example :

Base Class :

Public interface Pet{

   public String speak();

}

First subclass :

Public Class Dog implements Pet{
   public String speak(){
      return "dog speak.";
  }
}

Second subclass :

Public Class Duck implements Pet{
   public String speak(){
      return "duck speak.";
  
}

}

Factory Class :

public class PetFactory {

  public Pet getPet(String petType){
       Pet pet = null;
  }

  if("dog".equals(petType))
   pet = new Dog();
  else if("duck".equals(petType))
   pet = new Duck();
   return pet ;

}

Finally use the factory method to init the class :

 public class factoryMethodImp{

    public static void main(String args[]){
     
       PetFactory petFactory =new PetFactory();
        
       Pet pet = petFactory.getPet("");
       
       System.out.println(pet.speack());
   }

}

Thanks for Reading ......

See you in other Pattern .