I think I may have found an error in the cow roundup. I forgot the question number though, so I can't look it up again. The question was if 2 Integers with value 5 are '=='. The correct answer is yes. Shorts and Integers with a value between -128 and 127 are considered '==', even if they are different objects. With another value they are not '==', but are 'equals'. (Not good English, but I think you know what I mean). Can someone please confirm if that question was incorrect?
The roundup was written before Java 5 came out. Java 5 introduced generics where the behavior you describe was introduced. Before that, comparing two Integers was like comparing two Objects - where you had to use equals().
There was a discussion in this forum recently about upgrading the roundup for Java 1.4. I don't recall the outcome.
I'm quite sure (without having really tried it) that
new Integer(5) != new Integer(5)
even in Java 5, *but*
Integer.valueOf(5) == Integer.valueOf(5)
That is, the valueOf method (which is also used by autoboxing) does the caching. The constructor simply can't, technically - two calls *have* to create two distinct objects.
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