A Collection of an Abstract Class (or something like that…)

Question

The Scenario

I\'m making a program in Java that involves cars.

NOTE: I\'ve simplified this scenario (to the best of my ability) to make

Answer 1

You have to say it someplace - there's no getting around that. If you have many more kinds of Cars, you'll have to specify those attributes somewhere.

I don't see where subclassing helps you much, unless you can identify families of cars that are similar (e.g. sports cars, mini-vans, etc.).

One way to centralize all those attributes in one place is to instantiate Car using a factory method (it has a nice symmetry with manufacturing of physical cars, too).

Make the Car constructor private; have an enumeration of CarType that is the key into a Map of attributes for each type; pass in the CarType and get back a Car, fully initialized.

public class Car {

   private static final Map> DEFAULT_ATTRIBUTES;

   private Map attributes; 

   static {
      DEFAULT_ATTRIBUTES = new HashMap>();
      // Insert values here
   }

   private Car(Map initializers) {  
      this.attributes = new HashMap(initializers);
   }

   public static Car create(CarType type) {
      return new Car(DEFAULT_ATTRIBUTES.get(type));
   }
}