Converting Object[]arrayInteger to an int[] arrayInt

Question

Is it possible to convert and Object[]array to and integer Array.

The reason I am asking is because I added integers to an ArrayList and then converted this into and Object[]array.

ArrayList<Integer> list = new ArrayList<Integer>();
Object[] arrayNumbers = list.toArray();

Which would be the best way of getting this into and int[]array? All I need to do is to sort these numbers. Can I sort all my numbers in this arraylist without converting it into an int[]array?

Kind regards

"It depends how the sort is being done". (No, it is *not* required to have an `int[]` to sort a collection of integer objects; at the very least Integer implements Comparable.) — , Mar 28 '12 at 10:14
sorting is a different thing than converting a List into a int[] array. And the latter was already answered: http://stackoverflow.com/questions/3706470/convert-integer-list-to-int-array — Alonso Dominguez, Mar 28 '12 at 10:17

score 3 · Accepted Answer · answered Mar 28 '12 at 10:13

3

You should be doing this:

Integer[] arrayNumbers = list.toArray(new Integer[list.size()]);

If you just want to sort, simply use Collections.sort(list).

answered Mar 28 '12 at 10:13

adarshr

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score 3 · Answer 2 · answered Mar 28 '12 at 10:13

3

You can sort the list using Collections.sort method instead of all the conversions.

answered Mar 28 '12 at 10:13

MByD

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score 1 · Answer 3 · edited Apr 14 '12 at 12:36

1

You already have the list of integers in the variable list.

Iterate over list and keep a track of the index and add array[index] = i:

Algorithm not Java code, I'll leave that to you:

int index;

for (index =0; index <= list.Count(); index++) {
  array[index] = list[index];
}

edited Apr 14 '12 at 12:36

adarshr

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answered Mar 28 '12 at 10:14

Darren

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@adarshr did you event read my answer? I clearly state it's the algorithm not Java code.....why downvote? – Darren Apr 14 '12 at 11:53
Sorry, didn't notice. Reverted back. – adarshr Apr 14 '12 at 12:37

score 1 · Answer 4 · answered Mar 28 '12 at 10:14

1

You could use the following code to sort your values

 Arrays.sort(arrayNumbers);

answered Mar 28 '12 at 10:14

Chetter Hummin

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score 1 · Answer 5 · answered Mar 28 '12 at 10:15

1

You can sort the ArrayList using Collections.sort()

Collections.sort(list);

answered Mar 28 '12 at 10:15

len

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Converting Object[]arrayInteger to an int[] arrayInt

5 Answers5