Singleton Design Pattern

1. What is Singleton Design Pattern
2. Singleton as Creational Pattern
3. Implementation Guidelines
4. How do we implement a Singleton class


The Singleton pattern is both easy to understand as well as useful. I'll demonstrate first how to implement the Singleton pattern. Then I'll provide and example of its usefulness with a Scrabble example.


Threads can sometimes play havoc with this pattern, so I'll show you how to avoid those problems
Singleton Pattern belongs to Creational type pattern. As discussed in our previous video, Gang of four have defined five design patterns that belongs to creational design type category. Singleton is one among them and the rest are Factory, Abstract Factory, Builder and Prototype patterns. As the name implies, creational design type deals with object creation mechanisms. Basically, to simplify this, creational pattern explain us the creation of objects in a manner suitable to a given situation.


Singleton design pattern is used when we need to ensure that only one object of a particular class is Instantiated. That single instance created is responsible to coordinate actions across the application.


Concurrent access to the resource is well managed by singleton design pattern.


As part of the Implementation guidelines we need to ensure that only one instance of the class exists by declaring all constructors of the class to be private. Also, to control the singleton access we need to provide a static property that returns a single instance of the object.