Data structure for a body

Question

I'm writing a game in Java and am struggling to think how to appropriately manage character's bodies. My current structure is, in relevant part:

public class Character{
    private Body body;
    private Race race;
}

public class Body{
   private Leg rightLeg;
   private Leg leftLeg;
   //etc

   //the constructor takes a single Race argument and constructs a default
   //body for a member of that race

   public Leg getRightLeg(){
       return rightLeg;
   }

   ///etc
}

public class BodyPart(){
  //assorted instance variables and appropriate getters and setters
}

public class Leg extends BodyPart(){
  //leg specific stuff
}

public class AdvancedLeg extends Leg{
    //various different ways of improving body parts - magical enhancement 
    //for example.  There are a number of these classes 
    public AdvancedLeg(Leg l){
        //make leg better
    }
}

But this isn't working because each character must have the same basic body structure - 2 arms, 2 legs, one torso, one head, etc. Sure, I could have public class QuadrapodBody or similar (and make Body into an interface) but I certainly don't want to be getting in to public class OneHeadTwoRightArmsOneLeftArmOneRightLegOneLeftLegBody implements Body.

In essence I want to be able to flexibly assign body plans to each character and be able to manage getting body parts without having to write a potentially infinite number of classes each with a subtly different set of instance variables and getters/setters.

Hopefully my question is clear enough.

Answer 1

Instead of a separate variable for each bodypart, as in

private Leg rightLeg;
private Leg leftLeg;

have a list of bodyparts:

private List<BodyPart> bodyParts = new List<>();

You can then use getters which return one bodypart (or all bodyparts) which fulfill a specific criteria. For example:

// returns the first Head of the creature, or null when the creature has no head(s)
public BodyPart getHead() {
      return bodyParts.stream()
                      .findFirst(part -> part instanceof Head)
                      .orElse(null);
}

// returns all legs, arms, tentacles and prehensile tails
public BodyPart[] getExtremities() {
      return bodyParts.stream.filter(part -> part instanceof Extremity).toArray();
}