How can I simulate Haskell's “Either a b” in Java

Question

How can I write a typesafe Java method that returns either something of class a or something of class b? For example:

public ... either(boolean b) {
  if (b)         


        

Answer 1

Change your design so that you don't need this rather absurd feature. Anything you'd do with the return value would require some sort of if/else construct. It would just be very, very ugly.

From a quick Googling, it seems to me that the only thing Haskell's Either is commonly used for is error reporting anyway, so it looks like exceptions are actually to correct replacement.