java - Should all methods be static if their class has no member variables

Question

I've just had an argument with someone I work with and it's really bugging me. If you have a class which just has methods like calculateRisk or/and calculatePrice, the class is immutable and has no member variables, should the methods be static so as not to have to create an instance of the class each time. I use the following example:

public class CalcService {
  public int calcPrice(Trade trade, Date date) {
    ...
  }
  public double calcRisk(Trade trace, Date date) {
    ...
  }
}

Should those methods be static?

Answer 1

The class you describe is simply just a set of functions that operate on inputs only. It's perfectly reasonable to make such functions static methods of a class. Doing so groups them logically and eliminates possible name conflicts. The class in fact acts as a namespace and nothing more.