Replace Conditional with Polymorphism

You have a conditional that chooses different behavior depending on the type of an object. Move each leg of the conditional to an overriding method in a subclass. Make the original method abstract.

double getSpeed() {
    switch (_type) {
      case EUROPEAN:
        return getBaseSpeed();
      case AFRICAN:
        return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;
      case NORWEGIAN_BLUE:
        return (_isNailed) ? 0 : getBaseSpeed(_voltage);
    }
    throw new RuntimeException ("Should be unreachable");
  }

Enjoy!