Elegant Optional Arguments in Java13 Feb 2019
Today, an adventure in programming in the in-between, not quite programming in the small, not quite in the large either.
The problem is that we would like to have a Java method (or constructor) with optional parameters: parameters who take default value as arguments if not supplied.
The standard way to do this would be to generate overloads with only a subset of arguments. This is of course exponential in the number of optional parameters: with four of them, we're already generating 16 overloads! It's also dependent on optional parameters not sharing the same type, and requires one to remember the ordering of parameters.
A better solution: create a configuration object to hold all optional arguments. This is good, but shifts the issue of optional parameters to the instantiation of the configuration object. One solution is have a no-argument constructor and use setters to specify the non-default values. This can be relatively terse and elegant by means of the builder pattern.
It's also possible to forego the configuration object and store the configuration directly on the concerned object. But there is the risk to clutter the object, muddling the public interface of the class. It's better to separate concerns so that configuration data is separate from other fields ("work data", stored items, ...).
And there you have it, if you require more than one or two optional parameters, or you feel the set of optional parameters may grow, consider whipping up configuration object with the builder pattern!