Design Pattern

Java Design Patterns are divided into three categories – creational, structural, and behavioral design patterns. This post serves as an index for all the java design patterns articles I have written so far.

Creational Design Patterns

• Singleton Pattern
• Factory Pattern
• Abstract Factory Pattern
• Builder Pattern
• Prototype Pattern

Structural Design Patterns

• Adapter Pattern
• Composite Pattern
• Proxy Pattern
• Flyweight Pattern
• Facade Pattern
• Bridge Pattern
• Decorator Pattern

Behavioral Design Patterns

• Template Method Pattern
• Mediator Pattern
• Chain of Responsibility Pattern
• Observer Pattern
• Strategy Pattern
• Command Pattern
• State Pattern
• Visitor Pattern
• Interpreter Pattern
• Iterator Pattern
• Memento Pattern

Miscellaneous Design Patterns

• DAO Design Pattern
• Dependency Injection Pattern
• MVC Pattern

Creational Design Patterns

Creational design patterns provide solution to instantiate a object in the best possible way for specific situations

Singleton Pattern

To implement a Singleton pattern, we have different approaches but all of them have the following common concepts.

• Private constructor to restrict instantiation of the class from other classes.
• Private static variable of the same class that is the only instance of the class.
• Public static method that returns the instance of the class, this is the global access point for outer world to get the instance of the singleton class.

Factory Pattern

Factory design pattern is used when we have a super class with multiple sub-classes and based on input, we need to return one of the sub-class. This pattern take out the responsibility of instantiation of a class from client program to the factory class