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 calc

Answer 1

I would avoid making these static. Whilst at the moment that may make sense, you may in the future want to add some behaviour. e.g. at the moment you would have a default calculation engine (strategy):

CalcService cs = new CalcService();
cs.calcPrice(trade, date);

and later on you may want to add a new calculation engine:

CalcService cs = new CalcService(new WackyCalculationStrategy());
cs.calcPrice(trade, date);

If you make this class instantiatable, then you can create different instances and pass them around, instantiate on the fly etc. You can give them long-running behaviour (e.g. how many calculations involving trade X has this object done ? etc.)