final-keyword.md

Final Keyword in JAVA

Final keyword in java is a non-access modifier. It is used to restrict user from making any change in variable, method and classes.

1. Final Variable

If any variable is declared with keyword final, then the value of final variable can't be change, i.e. it becomes constant.

Example

class Student{
    //final variable
    final int id=50;
    void get_id(){
        id=100;
    }
    public static void main(String[] args){
        Student obj=new Student();
        obj.get_id();
    }
}

2. Final Method

If any method is declared with keyword final, then it can't be overridden.

Example

class Fruit{
    //final method
    final void run(){
        System.out.println("Inside Fruit Class");
    }
}
class Apple extends Fruit{
    void run(){
        System.out.println("Inside Apple Class");
    }
    public static void main(String[] args){
        Apple obj=new Apple();
        obj.run();
    }
}

3. Final Class

If any class is declared with keyword final, then it can't be inherited.

Example

//final class
final class Fruit{
}
class Apple extends Fruit{
    void run(){
        System.out.println("Inside Apple Class");
    }
    public static void main(String[] args){
        Apple obj=new Apple();
        obj.run();
    }
}