static block in java

                                    static keyword is a non-access modifier. static keyword can be used with 
class level variable, block, method and inner class or nested class.

                                    The static keyword in Java is used for memory management mainly. We can apply static keyword with
variables, methods, blocks and nested classes. The static keyword belongs to the class 
  than an instance of the class.

The static can be:

Variable (also known as a class variable)
Method (also known as a class method)
Block
Nested class

                                    // to create static block in java 
static{
  // code to be executed is placed here
}

// its placed inside class. its executed whenever the class is created not when its object is created or called.

                                    Static block is used to initialize the static data member. 
It is executed before the main method, 
at the time of classloading.

                                    Static Block:
 used for initializing statics members,
it belongs to the class and only one copy
and runs only once and before everything

I use it in configuration.reader class
  in my framework