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Answer 1

+1 A:

Otherwise you can't pass Object[] in.

BalusC 2010-02-11 18:29:46

@BalusC Is there ever a situation where you would pass to sort an array of Objects that you didn't know were all implementing `Comparable`? Any use of the sort method will be by objects that are `Comparable`. Seems like the only reason for accepting `Object[]` is that `Object` is used more frequently and is more familiar, and like ZeissS said, otherwise we would have to cast.

Jonathon 2010-02-11 18:34:41

There are still a lot of `toArray()` like methods in Java API which returns `Object[]`.

BalusC 2010-02-11 18:36:31

They could be implementing `Comparator<T>`, which is similar, but not the same as `Comparable<T>`

chama 2010-02-11 19:59:37

Answer 2

+2 A:

Because the second form would require a reallocation of the array. Even if you know that your array contains only comparables, you cannot just cast it to Comparable[] if the original type was Object[], since the array type does not match.

You can do:

Object[] arr = new String[0];
String[] sarr = (String[]) arr;

But you can't do:

Object[] arr = new Object[0];
String[] sarr = (String[]) arr;

So it's premature optimization :)

disown 2010-02-11 18:38:52

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