Java 'final' Keyword Tutorial

The final keyword in Java is used to restrict the user. The java final keyword can be used in many contexts. Final can be: variable, method, and class.

1. Java Final Variable

If you make any variable as final, you cannot change the value of final variable (It will be constant).

class Bike9 {
 final int speedlimit = 90; //final variable
 void run() {
  speedlimit = 400;  //Compile Time Error
 }
}

2. Java Final Method

If you make any method as final, you cannot override it.

class Bike {
  final void run() { System.out.println("running"); }
}
class Honda extends Bike {
   void run() { System.out.println("running safely with 100kmph"); } //Compile Time Error
}

3. Java Final Class

If you make any class as final, you cannot extend it.

final class Bike {}

class Honda1 extends Bike { //Compile Time Error
  void run() { System.out.println("running safely with 100kmph"); }
}