title: Should all methods be static if their class has no member variables
body: <p>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 <code>calculateRisk</code> or/and <code>calculatePrice</code>, 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:</p>
  
  <pre><code>public class CalcService {
    public int calcPrice(Trade trade, Date date) {
      ...
    }
    public double calcRisk(Trade trace, Date date) {
      ...
    }
  }
  </code></pre>
  
  <p>Should those methods be <code>static</code>?</p>