Is there an elegant way to get the first non null value of multiple method returns in Java?

Question

You have already seen this many times yourself, of that I\'m sure:

public SomeObject findSomeObject(Arguments args) {
    SomeObject so = queryFirstSource(args);         


        

Answer 1

I would write it like this (you may not need generics here but why not do it):

public static  Optional findFirst(Predicate predicate, A argument,
                                         Function... functions) {
  return Arrays.stream(functions)
          .map(f -> f.apply(argument))
          .filter(predicate::test)
          .findFirst();
}

And you can call it with:

return findFirst(Objects::nonNull, args, this::queryFirstSource,
                                       this::querySecondSource,
                                       this::queryThirdSource);

(assuming your queryXXX methods are instance methods)

The methods will be applied in order until one returns a value that matches the predicate (in the example above: returns a non null value).