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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[].

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Soniya
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6 Answers6

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Try this stuff,

     int arr[] = new int[arrList.size()];
        for (int i = 0; i < arrList.size(); i++) {
            arr[i] = Integer.parseInt(arrList.get(i));
        }
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
  • 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
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ArrayList<String> IdList = new ArrayList<String>();
int IdArray[].
    for (int i = 0; i < IdList.size(); i++) {
        IdArray[i] = (int)IdList.get(i));
    }
warbio
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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.

styken
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  • 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
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// 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);
}
Prince John Wesley
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String [] outStrArray = (String [])IdList.toArray()

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

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

Rob
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