Best practice for a Java method returning multiple values? [duplicate]

Question

I need a non-static instance method to return multiple values. For the sake of a simple example let's say these are boolean success and Object obj - but in the general case there could be more and they could be unrelated to each other. Can think of a few different ways of doing this:

Solution 1

private boolean aMethod(int aParam, Object obj) { ...set obj parameter & return value... }

Solution 2

private Pair<Boolean, Object> aMethod(int aParam) { ...set return pair values... }

Solution 3

private Object obj;
...
private boolean aMethod(int aParam) { ...set obj field & return value... }

Solution 4

private class MethodReturn { // Nested class - could be a separate class instead
    boolean success;
    Object obj;
    // ... Getters and setters omitted for brevity
}

private MethodReturn aMethod(int aParam) { ...set return object values... }

Are there any more possibilities I might have missed? And could anyone comment as to the pros and cons of each (and ideally, which might be the best to use under most circumstances)?

Answer 1

In general I'd go for the 4th or for a Map depending by the specific case, but if you need to return multiple unrelated values, I think that you have a serious design issue (Check https://en.wikipedia.org/wiki/Single_responsibility_principle)

In the specific case (after your comment), I'd definitely go with the 4th modeling the Response with all the required fields. Possibly you can also subtype with a ResponseSuccessful and ResponseFailure.