Final method and Final class

Final method: a method which has final keyword in its definition is called final method.

When a method should be defined as final?

If we do not want allow subclass to override super class method and to ensure that all sub classes uses the same super class method logic then that method should be declare as final method.

Final method cannot be overridden in subclass, violation leads to CE:

What is the difference between private and final methods?

Private method is not inherited, where as final method is inherited but cannot be overridden.

Can we overload final method in subclass?

Yes, we can overload final method in subclass.

Class Ex {

Final void m1 (int x) { }

}

Class Sa extends Ex{

Void m1(){}

}

Final Class:

A class which has final keyword in its definition is called final class.

When a class should be defined  as final?

In the below situations we must define class as final

1. If we do not want define all methods as final
2. If we do not want allow subclasses to extend our class functionality.

Sub class cannot be defined from final class, violation leads to CE:

Final class Ex{

}

Final class members are not final until they are declared as final members explicitly using final keyword.