Java Utililty Methods Collection to Array

List of utility methods to do Collection to Array

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Description

The list of methods to do Collection to Array are organized into topic(s).

Method

int[]toIntArray(final Collection c)
to Int Array 
if (c == null) {
    return null;
final int[] r = new int[c.size()];
int i = 0;
for (final Number n : c) {
    r[i++] = n.intValue();
return r;
int[]toIntArray(final Collection col)
Convert a collection of int to an array of ints. 
if (col == null)
    return null;
final int[] result = new int[col.size()];
int i = 0;
for (Integer val : col)
    result[i++] = val;
return result;
int[]toIntArray(final Collection collection)
to Int Array 
final int[] array = new int[collection.size()];
int i = 0;
for (Integer integer : collection)
    array[i++] = integer;
return array;
int[]toIntArray(final Collection values)
Converts a list of Integer objects into an array of primitive ints. 
final int[] items = new int[values.size()];
final Iterator<Integer> iterator = values.iterator();
for (int i = 0; i < items.length; i++) {
    items[i] = iterator.next();
return items;
Long[]toLongArray(Collection collection)
This method converts collection to Long Array. 
Long[] obj = new Long[collection.size()];
int index = 0;
Iterator<Long> iterator = collection.iterator();
while (iterator.hasNext()) {
    obj[index] = (Long) iterator.next();
    index++;
return obj;
...
long[]toLongArray(Collection collection)
Converts a Collection to a primitive long[] array. 
long[] collectionArray = new long[collection.size()];
int index = 0;
for (Long item : collection) {
    collectionArray[index++] = item;
return collectionArray;
String[]toStringArray(Collection collection)
Copy the given Collection into a String array. 
if (collection == null) {
    return null;
return (String[]) collection.toArray(new String[collection.size()]);
String[]toStringArray(Collection collection)
to String Array 
String[] result = new String[collection.size()];
int i = 0;
for (Object obj : collection) {
    result[i++] = obj.toString();
return result;
String[]toStringArray(Collection collection)
Copy the given Collection into a String array. 
if (collection == null) {
    return null;
return (String[]) collection.toArray(new String[collection.size()]);
String[]toStringArray(Collection collection)
to String Array 
if (collection == null) {
    return null;
if (collection.isEmpty()) {
    return EMPTY_STRING_ARRAY;
List<String> list = new ArrayList<>(collection.size());
for (Object o : collection) {
...