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Singleton class:

1. One Object

2. Return the same object whenever we create a new instance

We use Singleton class to prevent the creation of multiple classes.

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Eagle initialization: instance created at the starting of the server in web application.

Lazy initialization: instance created during first user call.

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Factory method: it's like a class calling constructor similarliy singleton class calls factory initialization.

Returns the object of the class.

Example :

1. Runtime run = Runtime.getRuntime();

2. Calender c1 = Calender.getinstance();

Here new operator is not used to create object. But we call static method: getRuntime() and getInstance(). this return object of this classes.

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Steps to Create Singleton Class:

1. create a static variable object of type class.

2. private constructor_name(){}

3. Creating a public method known as getInstance( ) in which we will create a instance and return the object