Final modifier in java

Another useful modifiers in regard to controlling class member usage is the final modifier. The final modifier specifies that a variable as a constant value or that a method cannot be overridden in a subclass. The final modifier makes class member is the final version allowed for the class.For creating symbolic constant you can use final modifier.

final public int CENT=100;//constant

the above is similar to const variable in c++,they must always be initialized upon declaration and their value can't change any time afterward.

final boolean FLAG=true;

Three usage of final are:

1. A final class cannot be inherited.

2. A final method cannot be changed by subclass (or) overriding.

3. A final data member cannot be changed after initialization(constant).

Final Class:

final class X{ }
class Y extends X
{
  void print()
  {
  System.out.println("inside block y");
  }
public static void main(String args[])
{
Y a=new Y();
a.print();
}
}

Output:

Example-2:

Final Variable:

class X
{ 
final int i=10;// constant variable

  void print()
  {
   i=20;
  }
public static void main(String args[])
{
X a=new X();
a.print();
}
}

Output: