Final

Final Variable, Final Method, Final Class

Value of final variables are fixed, that is once the value is assigned then it can’t be modified.

final variables are written in capital letters.

final variable can be initialised:
- During the declaration of the variable
- Inside instance block (just a block of curly brackets)
- Inside a static block (main method is also static), if the variable is also declared static
- Inside the constructor of class
  - As constructors can be overloaded, so the final variable must be initialized in every constructor.

class Test {
    final int LOW = 0;

    // This is not allowed, it will generate error.
    final int MIN;
    MIN = 1;

    final int AVG;

    {
        AVG = 5;
    }

    static final int MAX;

    static {
        // we cannot initialize/use non-static member in static block/method
        MAX = 9;
    }

    // also
    static void fun() {
        final int MAX;
        MAX = 9;
    }

    final int HIGH;

    Test() {
        HIGH = 10;
    }

    Test(int x) {
        HIGH = 10;
    }
}

It is not necessary to declare and initialize the final variable in the same statement.

Final in OOP

final class cannot be extended.
- It is used to restrict Inheritance.
final method cannot be overridden.
- It is used to restrict Polymorphism.

Last modified: 08 February 2026