Why aren't Java Collections remove methods generic?

Question

Why isn\'t Collection.remove(Object o) generic?

Seems like Collection could have boolean remove(E o);

Then, when you ac

Answer 1

Because it would break existing (pre-Java5) code. e.g.,

Set stringSet = new HashSet();
// do some stuff...
Object o = "foobar";
stringSet.remove(o);

Now you might say the above code is wrong, but suppose that o came from a heterogeneous set of objects (i.e., it contained strings, number, objects, etc.). You want to remove all the matches, which was legal because remove would just ignore the non-strings because they were non-equal. But if you make it remove(String o), that no longer works.