Builder pattern - Creational

• Building a Complex object using simple objects – step by step

         

Where to use ?

• To make a complex object by specifying only its type and content.
• To decouple the process of building a complex object from the parts that make up the object.
• Isolate code for construction and representation.
• To get finer control over the construction process.

Implementation example

• Item interface implemented by abstract classes Burger, Fries, ColdDrink
• Multiple concrete classes : CheeseBurger, FishBurger  and ChickenBerger extending Burger class
• Multiple concrete classes : Coke, Pepsi and ThumsUp extending ColdDrink class

• A class Meal having list of Item objects
• A class MealBuilder to prepare different kind of meals

• Client will use MealBuilder class to prepare meal as per need without knowing complexity of its creation.