Design choice for two almost identical classes

Question

I have two classes Boat and Mines, which have exactly the same methods and variables.

the only difference is that they are Initialized in different positions.

for Boat

xPosition = 3 yPosition = 4

for Mine

xPosition = 1 yPosition = 1

I've been told specifically not to use inheritance for this, what else could I use to improve the design

Without knowing more about the problem and the context, I do not think there's a good answer to this question. — plalx, Sep 14 '13 at 23:54
You can't use inheritance *at all*, or between the two classes? Between the two classes makes sense, since they're not really "related" to one another. — Makoto, Sep 14 '13 at 23:56
Well basically I have two classes that are essentially identical and it feels extremely wasteful to be retyping the same code for both classes (they both use exactly the same methods). Is there another way to handle this. — Koborl, Sep 14 '13 at 23:59
No, i've been told specifically for this not to use it at all. — Koborl, Sep 15 '13 at 00:05

score 1 · Answer 1 · answered Sep 15 '13 at 00:03

1

You could give both of them some sort of location class, give that class the X and Y positions, and make it a property of both the mine and the boat. Sad thing you'll need getters/setters for the location class nevertheless.

answered Sep 15 '13 at 00:03

windwarrior

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2
11

score 1 · Answer 2 · answered Sep 15 '13 at 00:03

The idea of object-oriented programming is for this exact reason.

Boat and Mine should not be classes, they should be new objects made from another class (we'll call it - waterStuff).

class waterStuff {
    public xPosition;
    public yPosition;
}

... then somewhere in the code you set them to new objects. I don't use Java so I'll do it as close as I can: (these would probably be inside another class using the waterStuff as a namespace for reference)

Boat = new waterStuff;
Mine = new waterStuff;

Boat->xPosition = 3;
Boat->yPosition = 4;
Mine->xPosition = 1;
Mine->yPosition = 1;

I wish I could be more java-specific but hopefully this gets you on the right track.

EDIT: Don't you just love CS101

score 0 · Accepted Answer · answered Sep 15 '13 at 00:06

If they only differ in the values of their members, inheritance seems somewhat pointless in any case. But having 2 unrelated classes would be worse.

How about something like this?

class SomeClass
{
   int xPosition, yPosition;
   enum Type
   {
      Boat, Mine
   }
   public SomeClass(Type type)
   {
      if (type == Type.Boat)
      {
         xPosition = 3;
         yPosition = 4;
      }
      else
      {
         xPosition = 1;
         yPosition = 1;
      }
      // assign 'type' to a class variable here if required
   }
}

Construct using:

new SomeClass(SomeClass.Type.Boat)

or:

new SomeClass(SomeClass.Type.Mine)

You may want to pick a better name than SomeClass.

Design choice for two almost identical classes

3 Answers3