Uses of keyword final in JAVA

Keyword " final " has three uses :

Use 1 : A variable can be declared as final, doing so prevents its contents from being modified. This means that we must initialize a final variable when it is declared.

For ex :

Final int a = 2 ;

The next two uses of Final apply to inheritance. 

Use 2 : Using Final to prevent overriding

While method overriding is one of the Java's most powerful feature, there will be times when we want to prevent it from occurring, to disallow a method from being overridden specify Final as a modifier at the start of its declaration.
Methods declared as final cannot be overridden.

class A
{      Final void math( )
        {
              System.out.println("This is a final method");
         }
}
class B extends A
{        void math( )         //illegal
          {       
                System.out.println("illegal"); 
           }
}



Use 3 : Using Final to prevent inheritance

Sometimes we want to prevent a class from being inherited. To do this precede the class declaration with final. Declaring a class as final implicitly declares all of its methods as final too.
As we expect it is illegal to declare a class as both abstract and final since an abstract class is incomplete by itself and relies upon its subclasses to provide complete implementations.

final class A
{    ......
      ........
      ........
}
class B extends A                    // illegal
{ 
}



Hope this helped.....