Singleton pattern

• This pattern involves a single class which is responsible to create an object while making sure that only single object gets created.
• SingleObject class have its constructor as private and have a static instance of itself.                                         

1. Create a Singleton Class.

public class SingleObject { //create an object of SingleObject private static SingleObject instance = new SingleObject(); //make the constructor private so that this class cannot be //instantiated private SingleObject(){} //Get the only object available public static SingleObject getInstance(){ return instance; } public void showMessage(){ System.out.println("Hello World!"); } }

1. Get the only object from the singleton class.

public class SingletonPatternDemo { public static void main(String[] args) { //illegal construct //Compile Time Error: The constructor SingleObject() is not visible //SingleObject object = new SingleObject(); //Get the only object available SingleObject object = SingleObject.getInstance(); //show the message object.showMessage(); } }