Java Utililty Methods Collection to Array

Iterator iter = coll.iterator();
int[] arr = new int[coll.size()];
int i = 0;
while (iter.hasNext()) {
    arr[i++] = (Integer) iter.next();
return arr;

if (coll == null || coll.isEmpty()) {
    return null;
final int[] arr = new int[coll.size()];
final Iterator<Integer> it = coll.iterator();
int i = 0;
for (; it.hasNext();) {
    arr[i++] = it.next();
...

if (collection == null)
    throw new RuntimeException("Can't do toIntArray. Collection is Null");
int[] result = new int[collection.size()];
int i = 0;
for (Integer el : collection)
    result[i++] = el;
return result;

if (collection == null) {
    return null;
return (Integer[]) collection.toArray(new Integer[collection.size()]);

int[] newArray = new int[collection.size()];
if (collection instanceof List) {
    List<Integer> list = (List<Integer>) collection;
    for (int i = 0; i < list.size(); i++) {
        Integer value = list.get(i);
        newArray[i] = value.intValue();
} else {
...

int array[] = new int[collection.size()];
int index = 0;
Iterator<Integer> it = collection.iterator();
while (it.hasNext()) {
    array[index++] = it.next();
return array;

int[] out = new int[ints.size()];
int i = 0;
for (Integer boxed : ints) {
    out[i++] = boxed.intValue();
return out;

int n = list == null ? 0 : list.size();
int[] arr = new int[n];
if (list != null) {
    int i = 0;
    for (int d : list)
        arr[i++] = d;
return arr;
...

if (list == null || list.isEmpty()) {
    return EMPTY_INT_ARRAY;
int[] result = new int[list.size()];
int i = 0;
for (Integer integer : list) {
    result[i++] = integer;
return result;

int[] result = new int[values.size()];
int i = 0;
for (int value : values)
    result[i++] = value;
return result;