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.....
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.....
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