Java - Inheritance and final

Introduction

You can disable subclassing for a class by declaring the class final.

A final class cannot be subclassed.

final class

The following snippet of code declares a final class named S:

public final class S{
}

The following declaration of class will not compile:

// Won't compile. Cannot inherit from S
public final class C extends S{
}

final method

You can declare a method as final.

A final method cannot be overridden or hidden by a subclass.

Demo

class A {
  public final void m1() {
  }/*from  ww  w .j a  v a2s.co m*/

  public void m2() {
  }
}

class B extends A {
  // Cannot override A.m1() here because it is final in class A
  // OK to override m2() because it is not final in class A
  public void m2() {
    // Code goes here
  }
}