Constructors in a class

[Ravi Hyd]

I want to know whether we can create a Private default constructor in a class. Can anybody explain what is Singleton class?

[Manuel Moons]

Yes, it is possible to create a private default Constructor.

If all constructors are private you cannot create an instance from outside that class.

If you create a public static method that always returns the same instance of that class you have used the singleton pattern.

Look at the example:

    public class Singleton {
      private Singleton() {}
 
      private static Singleton instance;
      public static Singleton getInstance() {
           if(instance == null) {
              instance = new Singleton();
           }
           return instance;
      } 
    }