How is the Singleton Pattern implemented in Java?

Answer 1

Singleton pattern is a design pattern wherein there is only one instance of a particular class at any point during the system existence. It is implemented by:

a. Making the constructor private (so that no other class can create an object of this class using the new keyword) and

b. Writing a getInstance() method which will return an instance of the class.

Ex:

Public class SingletonExample {

Private static SingletonExample _instance;

private SingletonExample() {

super();

… //Other initialization code

}

public static SingletonExample getInstance() {

If(_instance == null){

_instance = new SingletonInstance();

}

Return _instance;

}

}

Any class that wants an instance of this class can do as follows:

SingletonExample object = SingletonExample.getInstane();