kalyanramswamy / design-patterns

design patterns with examples

DesignPattern

Types of Patterns

1. Creational : Creational design patterns abstract the instantiation process. They help make a system independent of how its objects are created,composed, and represented.

   • Factory Method: Subclass of object that is instantiated
   • Abstract Factory: Families of product objects
   • Builder: How a composite object get created
   • Prototype: Class of object that is instantiated
   • Singleton: The sloe instance of a class

2. Structural : Structural patterns are concerned with how classes and objects are composed to form larger structures. Structural class patterns use inheritance to compose interfacesor implementations.

   • Adapter: Interface to an object
   • Bridge: Implementation of an object
   • Composite: Structure and composition of an object
   • Decorator: Responsibility of an object without subclassing
   • Facade: Interface to a subsystem
   • Flyweight: Storage cost of objects
   • Proxy: How an object is accessed; its location

3. Behavioral

   • Chain Of Responsibility: Object that can fulfill a request
   • Command: When and how a request is fulfilled
   • Interpreter: Grammar and interpretation of a language
   • Iterator: How an aggregate's elements are accessed, traversed
   • Mediator: How and which objects interact with each other
   • Memento: What private information is stored outside an object, and when
   • Observer: Number of objects that depend on another object; how the dependent objects stay up to date
   • State: states of an object
   • Strategy: an algorithm
   • Template Method: steps of algorithm
   • Visitor: operations that can be applied to object(s) without changing their class(es)

Simple meaning of instantiate is creating an object from class.

ClassName obj = new ClassName();