public abstract class ThreeDShape implements MyComparable<ThreeDShape> {

  public final boolean isLarger(ThreeDShape other) {
      if( this.getArea() > other.getArea() ) 
        return true;
      else 
        return false;
  }
  
  public final boolean isEqual(ThreeDShape other) {
      if( this.getArea() == other.getArea() ) 
        return true;
      else 
        return false;
  }
  
  public abstract double getArea();
  public abstract double getVolume(); 
}