Slightly deceiving error message on Collectors.toMap

[Michael Nascimento]

On Thu, Apr 17, 2014 at 1:04 PM, Peter Levart <peter.levart at gmail.com> wrote:
> But the two values are the same (if the key->value mapper function *is* a
> function), aren't they?

No, for example:

Stream.of(1, 1).collect(toMap(identity(), i -> Math.random()));

Another example would be something like:

cities.stream().collect(toMap(City::getName, identity()));

If there are cities from different states in the collection, their
names might collide. Printing both values (with a decent toString)
will help developers to figure out their mistake.

Regards,
Michael