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Factory Pattern

The Factory Pattern is a creational design pattern that provides a way to create objects without specifying the exact class of object that will be created. This is done by creating objects through a common interface of a factory class, rather than directly with a constructor. The Factory Pattern allows for new types of products to be added without changing the structure of the client code. It promotes loose coupling between the creation of an object and its use.

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34 views4 pages

Factory Pattern

The Factory Pattern is a creational design pattern that provides a way to create objects without specifying the exact class of object that will be created. This is done by creating objects through a common interface of a factory class, rather than directly with a constructor. The Factory Pattern allows for new types of products to be added without changing the structure of the client code. It promotes loose coupling between the creation of an object and its use.

Uploaded by

Nourhane Ibrahim
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Factory Pattern

 One of the most popular design patterns in Java


 Design patterns: well described solution for solving specific task or problem.
 Advantages: 1- Reusable in multiple project.
2- Define system structure.
3- Clarity to the system architecture.
4- Transparency to the design in the application.
5- Well proved and testified solution.
6- Spend less time to solve a problem.
7- Factory Method is that it can return the same instance multiple
times, or can return a subclass rather than an object of that exact type.
 Disadvantages:
1- Indirection may reduce performance.
2- Limitation (may not be addressed specific issues).

 Types:

 Comes under creational pattern.


 Objectif: Creates an object by calling a method instead of a constructor.
 Demo :
Step 1
Create an interface.
Operator.java
public interface Operator {
void pay();
}

Step 2
Create concrete classes implementing the same interface.
Mtn.java
public class Mtn implements Operator {

@Override
public void pay() {
System.out.println("Inside Mtn::pay() method.");
}
}
Vodaphone.java
public class Vodaphone implements Operator {

@Override
public void pay() {
System.out.println("Inside Vodaphone::pay() method.");
}
}
Orange.java
public class Orange implements Operator {

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

Step 3
Create a Factory to generate object of concrete class based on given information.
ShapeFactory.java
public class OperatorFactory {

//use getOperator method to get object of type operator


public Operator getOperator(String OperatorType){
switch (OperatorType)
{
case "MTN":
return new Mtn();
case "Vodaphone":
return new Vodaphone();
case "Orange":
return new Orange();
case:
throw new NotSupportedException ();
}

}
}

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) {


OperatorFactory opFactory = new OperatorFactory ();

//get an object of Mtn and call its pay method.


Operator op = opFactory.getOperatoe("MTN");

//call pay method of Mtn


op.pay();

//get an object of Vodaphone and call its pay method.


Operator op2 = opFactory.getOperatoe("Vodaphone");
Op2.pay();
}
}

 Best Practice:
 Use the Factory Method when you don’t know beforehand the exact types and
dependencies of the objects : to add a new product type to the app, we’ll only need
to create a new creator subclass and override the factory method in it.
 Use the Factory Method when you want to save system resources by reusing existing
objects instead of rebuilding them each time.

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