> In Java, if you have an expression e, you can replace any sub expression, x, with another y, that has the same denotation, without changing the denotation of e.

Well of course, as long as you make the denotation fine grained enough! Any language is referentially transparent if every expression is only denotationally equal to itself. The point is that Haskell's equational theory is very rich and Java's isn't. From there we conclude that Haskell's is more useful. Whether it's useful enough is another issue, but claiming the Java is referentially transparent is almost vacuous.