Java HashSet<Integer> to int array

Question

I've got a HashSet with a bunch of (you guessed it) integers in it. I want to turn it into an array, but calling

hashset.toArray();

returns an array of Object type. This is fine, but is there a better way to cast it to an array of int, other than iterating through every element manually? A method I want to pass it to

void doSomething(int[] arr)

Won't accept the Object[] array, even if I try casting it like

doSomething((int[]) hashSet.toArray());

Answer 1

Nope; you've got to iterate over them. Sorry.

Answer 2

Have you seen this site?

Answer 3

public int[] toInt(Set<Integer> set) {
  int[] a = new int[set.size()];
  int i = 0;
  for (Integer val : set) a[i++] = val;
  return a;
}

Now that I wrote the code for you it's not that manual anymore, is it? ;)

Answer 4

Apache's ArrayUtils has this (it still iterates behind the scenes):

doSomething(ArrayUtils.toPrimitive(hashset.toArray()));

They're always a good place to check for things like this.