Overriding a method in inner class of parent class

Do you want to override (for absence of a better word) a function in the inner class of the parent class. Here is a good way of doing it:

class House {
  public class Room {
      public int minLength() {
          return 100;
      }
  }

  public Room getRoom() {
      return new Room();
  }
}

class Bungalow extends House {
  public class Room extends House.Room {
      @Override
      public int minLength() {
          return 1000;
      }
  }

  @Override
  public Room getRoom() {
      return new Room();
  }
}

Whenever you want to instantiate a Room of a House (either a House or a Bungalow), use the getRoom() method of the House.

Hence, following method shall print:

100
1000

on the screen:

public static void main(String args[]){
  House h=new House();
  System.out.println(h.getRoom().minLength());
  h=new Bungalow();
  System.out.println(h.getRoom().minLength());
}