Abstract Factory Design Pattern in Java

By -

Type:  Creational Design Pattern


Summary

Provide an indirect way to create object that abstracts the creation of families of related objects without directly specifying their concrete Classes. The Factory owns the responsibility create objects. Client is not aware of how to create the object.

Details

It is similar to Factory method design pattern. Only difference is that rather than returning instance of Subclasses, Abstract factory method can create object of Subclasses having different inheritance hierarchy. Generally Abstract Factory will return different Factories, which in turn can be used to Objects

Abstract Factory is used when we want to create objects by Clients and control which instance should be returned. It is used in DAO (Data Access Object).


It can be used to design Platform dependent software solution, by providing platform specific implementations.  

Example

We will extend the example of Sales Man and Different types of Car (SUV, Sedan) to have different type of Car's in terms of its engine (Electric, Gasoline). Now rather than giving an option to create instance of concrete Class like SUV and Sedan, we have an Abstract Factory Class which can return Factory for either ElectricCar or GasolineCar.

Class Diagram


Sample Code



// interface for Engine Factory
public interface EngineProvider {

  public Car getSedan();

  public Car getSuv();
}

// electric Car Factory
public class ElectricCarFactory implements EngineProvider {

  @Override
  public Car getSedan() {
    return new ElectricSedan();
  }

  @Override
  public Car getSuv() {
    return new ElectricSUV();
  }
}


//gasoline Car Factory
public class GasolineCarFactory implements EngineProvider{
 
  @Override
  public Car getSedan() {
    return new GasolineSedan();
  }

  @Override
  public Car getSuv() {
    return new GasolineSUV();
  }

}


// Car Factory Class which interacts with Clients
public class CarFactory {

  private static EngineProvider factory;

  public static EngineProvider getProvider(String providerName) {
    switch (providerName) {
      case "ELECTRIC":
        factory = new ElectricCarFactory();
        break;
      case "GASOLINE":
        factory = new GasolineCarFactory();
        break;

    }
    return factory;
  }
}

Github Code 


Advantages

Provide a standard interface by which family of objects can be created
Internally in the Abstract factory we can use other design patterns like Flyweight or Proxy or Prototype pattern as per the need.

Disadvantages

Sometime supporting for new Object type might lead to changing the interface and refactoring the existing implementation.

References

Comments

Post a Comment

Popular posts from this blog

Difference between volatile and synchronized

By -
volatile is a field modifier, while synchronized modifies code blocks and methods. So we can specify three variations of a simple accessor using those two keywords: int i1; int geti1() {return i1;} volatile int i2; int geti2() {return i2;} int i3; synchronized int geti3() {return i3;} geti1() accesses the value currently stored in i1 in the current thread . Threads can have local copies of variables, and the data does not have to be the same as the data held in other threads. In particular, another thread may have updated i1 in it's thread, but the value in the current thread could be different from that updated value. In fact Java has the idea of a "main" memory, and this is the memory that holds the current "correct" value for variables. Threads can have their own copy of data for variables, and the thread copy can be different from the "main" memory. So in fact, it is possible for the "main"
Read more

Converting Java Map to String

By -
Java Collections framework, String manipulation etc is something that we often encounter in Development process. For processing collections (like checking null/empty, Intersection, Disjunction) We do have some of the very use full libraries. Some of the Collection related libraries are Apche Commons Collections and Google  Collections(Guava). Problem Use Case This article explains how to convert a Java Map to String(and vice versa) using different libraries and technique. One way is to use StringBuilder(Or String) and loop though the Map and build the String by applying some sort of separator ( for key:value and entry). Here we have to take care of the null value etc. Without Any Library If we want to convert the map to a String with key value separator and also individual entry seperator in the resulting String, we have to write code for that. For a simple Map, we have to iterate though the map, take care of the null values etc. Following is a sample to get String built
Read more

Masking Credit Card number in Java

By -
Sometimes we need to mask crucial information like Credit Card Numbers, CVV numbers etc before storing  or logging the information. This example mask Credit Card Number (Except last 4 Digit) from a Text which contains information along with Credit Card Number. The following example demonstrates how we can easily mask the credit card with Matcher and Pattern Classes. This Sample Code uses Matcher and Pattern. Pattern Used in this sample is not optimized for Credit Card Numbers, this pattern will get any numerical numbers in the String Content.  Based on the Credit Card Type a more efficient and Strict RegEx can be used to mask the Credit Card. /**Mask the Credit card number but last four digit value **/   Pattern PATTERN = Pattern.compile( "[0-9]+" ); String message = content; Matcher matcher = PATTERN.matcher(message); String maskingChar = "*"; StringBuilder finalMask = new StringBuilder(maskingChar);
Read more