Abstract Factory Pattern using Java

[shazin]

Factory Pattern is a widely used efficient pattern that eliminates the need of Constructing objects in the client code. Instead the Factory creates and delivers objects as required by the client. This method eliminates the need to instantiate (use the new keyword) with a client code.

A small example demonstrates this pattern.
Beverage.java

Code:

public interface Beverage {
    void addSugar();
    void stir();
}

Tea.java

Code:

public class Tea implements Beverage {
    public void addSugar(){
        System.out.println("Sugar Added to Tea");
    }

    public void stir(){
        System.out.println("Tea stirred");
    }
}

Coffee.java

Code:

public class Coffee implements Beverage {
    public void addSugar(){
        System.out.println("Sugar Added to Coffee");
    }

    public void stir(){
        System.out.println("Coffee stirred");
    }
}

BeverageFactory.java

Code:

public abstract class BeverageFactory {
    public static final int COFFEE = 1;
    public static final int TEA = COFFEE + 1;

    public static Beverage getBeverage(int whichBeverage){
        switch(whichBeverage){
            case 1 : return new Coffee();
            case 2 : return new Tea();
            default : return null;
        }
    }

    
}

FactoryTest.java

Code:

public class FactoryTest {
    public static void main(String[] args){
        Beverage tea = BeverageFactory.getBeverage(BeverageFactory.TEA);
        
        tea.addSugar();    
        tea.stir();

        Beverage coffee = BeverageFactory.getBeverage(BeverageFactory.COFFEE);        

        coffee.addSugar();
        coffee.stir();
    }
}