Factory Design Patterns

FACTORY DESIGN PATTERN

This type of design pattern comes under creational pattern as this pattern provides one of the best ways to create an object.

Factory design pattern is used when we have a super class with multiple sub-classes and based on input,
we need to return one of the sub-class.
This pattern take out the responsibility of instantiation of a class from client program to t
he factory class.

In Factory pattern, we create object without exposing the creation logic to the client and refer to newly
created object using a common interface.

Implementation

We're going to create a Shape interface and concrete classes implementing the Shape interface.
A factory class ShapeFactory is defined as a next step.

FactoryPatternDemo, our demo class will use ShapeFactory to get a Shapeobject.
It will pass information (CIRCLE / RECTANGLE / SQUARE) to ShapeFactory to get the type of object it needs.

Step 1

Create an interface.

Shape.java

public interface Shape {
  void draw();
}

Step 2

Create concrete classes implementing the same interface.

Rectangle.java

public class Rectangle implements Shape {

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

Square.java

public class Square implements Shape {

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

Circle.java

public class Circle implements Shape {

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

Step 3

Create a Factory to generate object of concrete class based on given information.

ShapeFactory.java

public class ShapeFactory {

  //use getShape method to get object of type shape
  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;
  }
}

Step 4

Use the Factory to get object of concrete class by passing an information such as type.

FactoryPatternDemo.java

public class FactoryPatternDemo {

  public static void main(String[] args) {
     ShapeFactory shapeFactory = new ShapeFactory();

     //get an object of Circle and call its draw method.
     Shape shape1 = shapeFactory.getShape("CIRCLE");

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

     //get an object of Rectangle and call its draw method.
     Shape shape2 = shapeFactory.getShape("RECTANGLE");

     //call draw method of Rectangle
     shape2.draw();

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

     //call draw method of circle
     shape3.draw();
  }
}

Step 5

Verify the output.

Inside Circle::draw() method.
Inside Rectangle::draw() method.
Inside Square::draw() method.

In OBP case we have individual adapters for Address,Contact Point,Employment Details,Party to account,Party to Party,Party Names,etc.

All these adapters extend AbstractIntegrationAdapter (for some common methods) and implement IIntegrationAdapter(similar to shape in the above exmaple)

IIntegrationAdapter adapter =IntegrationAdapterFactory.getInstance().fetchAdapterInstance(sessionContext,  
                                                      "party_service_core_PartyAddressApplicationService_PartyAddressDTO_updatePartyAddress");

All are factory methods in OBP case were singleton and we also have SyncIntegrationAdapter file which stored key and value like

public static final String party_service_core_PartyAddressApplicationService_PartyAddressDTO_updatePartyAddress =
"com.ofss.fc.app.adapter.impl.integration.mdm.UpdatePartyAddressAdapter";

Thus anytime we need to change the Adaper file we just needed to change in the SyncIntegrationAdaper file
no need to change everytime in post hooks of service where we were fetching adapter instances.