How to copy elements from ArrayList to int Array in java

Question

Possible Duplicate:
convert String arraylist to string array in java?

Following is my code

ArrayList<String> IdList = new ArrayList<String>();

and I want to copy items from IDList to int IdArray[].

You should start with an ArrayList in the first place if it doesn't matter XD — Rob, Oct 14 '11 at 09:08
@ All: Thanks for your help. Following code helped me out String[] array = Idlist.toArray(new String[list.size()]); — Soniya, Oct 14 '11 at 10:08

score 6 · Answer 1 · answered Oct 14 '11 at 09:09

6

Try this stuff,

     int arr[] = new int[arrList.size()];
        for (int i = 0; i < arrList.size(); i++) {
            arr[i] = Integer.parseInt(arrList.get(i));
        }

answered Oct 14 '11 at 09:09

Lalit Poptani

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gave ArrayIndexOutOfBoundException – Soniya Oct 14 '11 at 09:40
int asize= IdList.size(); int arr[] = new int[asize]; for (int i = 0; i < asize); i++) { arr[i] = Integer.parseInt(IdList.get(i)); } – Soniya Oct 14 '11 at 10:00
@ Lalit: Thanks. I got the solution. – Soniya Oct 14 '11 at 10:43
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/4261/discussion-between-soniya-and-lalit-poptani) – Soniya Oct 14 '11 at 10:43

score 1 · Answer 2 · answered Oct 14 '11 at 09:09

1

String [] outStrArray = (String [])IdList.toArray()

answered Oct 14 '11 at 09:09

1

This will throw a ClassCastException because `Collection.toArray()` returns a `Object[]`. – x4u Oct 14 '11 at 09:28

score 1 · Answer 3 · answered Oct 14 '11 at 09:13

1

ArrayList<String> IdList = new ArrayList<String>();
int IdArray[].
    for (int i = 0; i < IdList.size(); i++) {
        IdArray[i] = (int)IdList.get(i));
    }

answered Oct 14 '11 at 09:13

warbio

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score 0 · Answer 4 · answered Oct 14 '11 at 09:06

0

int[] IdArray = IdList.toArray();

However, this will probably fail because you're trying to convert a string-arraylist to an int-array..

answered Oct 14 '11 at 09:06

Rob

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score 0 · Answer 5 · answered Oct 14 '11 at 09:07

0

I think you must iterate through all items, which are Strings, and parse each of them into an int to populate your new int[] array.

answered Oct 14 '11 at 09:07

styken

74
6

Did you mean, Iterator itr = IdList.iterator(); int IdArray[]={}; int d=0; while(itr.hasNext()) { String topic_id = (String) itr.next(); IdArray[d]= Integer.parseInt(topic_id); d++; System.out.print("============"+topic_id ); } – Soniya Oct 14 '11 at 09:11

score 0 · Answer 6 · answered Oct 14 '11 at 09:08

0

// String array
String[] arr = idList.toArray(new String[0]);
// for int array
int[] iarr = new int[arr.length];
int idx = 0;
for(String s : arr) {
   iarr[idx++] = Integer.parseInt(s);
}

answered Oct 14 '11 at 09:08

Prince John Wesley

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How to copy elements from ArrayList to int Array in java

6 Answers6