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Design Patterns

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اسفند

 Design Patterns


Design patterns are solutions to software design problems you find again and again in real-world application development. Patterns are about reusable designs and interactions of objects.

The 23 Gang of Four (GoF) patterns are generally considered the foundation for all other patterns. They are categorized in three groups: Creational, Structural, and Behavioral (for a complete list see below).

To give you a head start, the C# source code for each pattern is provided in 2 forms: structural and real-world. Structural code uses type names as defined in the pattern definition and UML diagrams. Real-world code provides real-world programming situations where you may use these patterns.

A third form, .NET optimized, demonstrates design patterns that fully exploit built-in .NET 4.5 features, such as, generics, attributes, delegates, reflection, and more. These and much more are available in our .NET Design Pattern Framework 4.5. You can see the Singletonpage for a .NET 4.5 Optimized example.



Creational Patterns

  Abstract Factory

Creates an instance of several families of classes

  Builder

Separates object construction from its representation

  Factory Method

Creates an instance of several derived classes

  Prototype

A fully initialized instance to be copied or cloned

  Singleton

A class of which only a single instance can exist

 

Structural Patterns

  Adapter

Match interfaces of different classes

  Bridge

Separates an object’s interface from its implementation

  Composite

A tree structure of simple and composite objects

  Decorator

Add responsibilities to objects dynamically

  Facade

A single class that represents an entire subsystem

  Flyweight

A fine-grained instance used for efficient sharing

  Proxy

An object representing another object

 

Behavioral Patterns

  Chain of Resp.

A way of passing a request between a chain of objects

  Command

Encapsulate a command request as an object

  Interpreter

A way to include language elements in a program

  Iterator

Sequentially access the elements of a collection

  Mediator

Defines simplified communication between classes

  Memento

Capture and restore an object's internal state

  Observer

A way of notifying change to a number of classes

  State

Alter an object's behavior when its state changes

  Strategy

Encapsulates an algorithm inside a class

  Template Method

Defer the exact steps of an algorithm to a subclass

  Visitor

Defines a new operation to a class without change

 

 

 

Core Java Design Patterns

In core java, there are mainly three types of design patterns, which are further divided into their sub-parts:

1.Creational Design Pattern

  1. Factory Pattern

  2. Abstract Factory Pattern

  3. Singleton Pattern

  4. Prototype Pattern

  5. Builder Pattern.

2. Structural Design Pattern

  1. Adapter Pattern

  2. Bridge Pattern

  3. Composite Pattern

  4. Decorator Pattern

  5. Facade Pattern

  6. Flyweight Pattern

  7. Proxy Pattern

3. Behavioral Design Pattern

  1. Chain Of Responsibility Pattern

  2. Command Pattern

  3. Interpreter Pattern

  4. Iterator Pattern

  5. Mediator Pattern

  6. Memento Pattern

  7. Observer Pattern

  8. State Pattern

  9. Strategy Pattern

  10. Template Pattern

  11. Visitor Pattern

 

 

Creational design patterns

Creational design patterns are concerned with the way of creating objects. These design patterns are used when a decision must be made at the time of instantiation of a class (i.e. creating an object of a class).

But everyone knows an object is created by using new keyword in java. For example:

1.    StudentRecord s1=new StudentRecord();  

Hard-Coded code is not the good programming approach. Here, we are creating the instance by using the new keyword. Sometimes, the nature of the object must be changed according to the nature of the program. In such cases, we must get the help of creational design patterns to provide more general and flexible approach.

Types of creational design patterns

There are following 6 types of creational design patterns.

  1. Factory Method Pattern

  2. Abstract Factory Pattern

  3. Singleton Pattern

  4. Prototype Pattern

  5. Builder Pattern

  6. Object Pool Pattern

 


  • سید یاسر نوراللهی