Inheritance, abstract, interface

Bathroom.java

public class Bathroom extends Room implements Flushable{
  
  // inherited attr
  // length
  // width
  
  public double bathtub = 0.5;
  public boolean hasShower;
  
  @Override 
  public int getArea(){
    // can be overridden?
  } 
  
  // inherited from Flushable
  public void flush(){
    
  }
  public void plunge(){
    
  }
  public void callOutForToiletPaper(){
    
  }
  
}

building.java

public class Building{
  
  // class variables
  Door mFrontDoor
  Door mLastDoor
  String mAddress
  
  // overloaded constructors
  public Building(){
  }
  public Building(String address){
    mAddress = address;
  }
  
  // accessors
  public getAddress(){
    return mAddress;
  }
  public setAddress(String address){
    mAddress = address;
  }
  
}

Flushable.java

public interface Flushable{
  public void flush(){}
  public void plunge(){}
  public void callOutForToiletPaper(){}
}

house.java

public class House extends Building{

  // constants
  Room mLivingRoom
  List<Bathoom> mBathrooms = ArrayList<Bathroom>();
  
  // constructor
  public House(){}
  
  public List<Bathroom> getBathrooms(){
    return mBathrooms;
  }
}

room.java

abstract public class Room{

  int mLength
  int mWidth

  Room(){}
  Room(int length, int width){
    mLength = length;
    mWidth = width;
  }

  public int getArea(){
    return mLength * mWidth
  }

}