We have discussed Pizza design problem and different naive approaches to solve it in set 1. We have also introduced Decorator pattern in Set 2.
In this article, design and implementation of decorator pattern for Pizza problem is discussed. It is highly recommended that you try it yourself first.
The new class diagram (Click on the picture to see it clearly)
- Pizza acts as our abstract component class.
- There are four concrete components namely PeppyPaneer , FarmHouse, Margherita, ChickenFiesta.
- ToppingsDecoratoris our abstract decorator and FreshTomato , Paneer, Jalapeno, Barbeque are concrete decorators.
Below is the java implementation of above design.
Margherita Cost :100 FarmHouse, Fresh Tomato , Paneer Cost :310
Notice how we can add/remove new pizzas and toppings with no alteration in previously tested code and toppings and pizzas are decoupled.
Basic Milk shake MilkShake Price of MilkShake : 30 Mango decorated Milk shake MilkShake decorated with Mango Price of Mango MilkShake : 70 Vanilla decorated Milk shake MilkShake decorated with Vanilla Price of Vanilla MilkShake : 110
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