Question

Lets say I have a class A that is fairly simple like this –

public class A{
  private int randomField = 0;
  protected int key;
  protected double dmg;
}

Now I want to write a number of sub-classes that inherit the protected fields and only differ based on the initial values that are assigned to those fields – for example, if I wrote two subclasses B and C, the only difference between those two sub-classes would be that the values key and dmg would have different values. They would share a method, set, which would be exactly the same, in that it would affect the same variable.

I find when I’m writing these sub-classes I’m repeating myself, as I just change the constructor to set different initial values to key and dmg, and simply copy and paste the set method.

Is there a ‘good’ way to do this?

Answer 1

This is not a place where you should be sub-classing and in fact is a gross over-use of inheritance. If the only difference between “subclasses” are initial states of the objects, then use only one class for all, and instead simply set the states in a constructor or factory to create instances of the desired state.

e.g.,

public class A{
  private int randomField = 0;
  private int key;
  private double dmg;

  public A(int key, double dmg) {
    this.key = key;
    this.dmg = dmg;
  }

  // getters and possibly setters...
}