Java Utililty Methods Collection First

List of utility methods to do Collection First

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Description

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

Method

TgetFirstItem(Collection collection)
Get the 1st element of the collection. 
if (isEmpty(collection)) {
    return null;
for (T item : collection) {
    return item;
return null;
XgetFirstItem(Collection c)
Returns the first item in the collection or null if the collection is empty 
X o;
if (c == null || c.isEmpty()) {
    o = null;
} else if (c instanceof List) {
    o = ((List<X>) c).get(0);
} else {
    o = c.iterator().next();
return o;
TgetFirstItemInCollection(Collection collection)
get First Item In Collection 
for (T item : collection) {
    return item;
return null;
ListgetFirstN(Collection objects, int n)
get First N 
if (objects == null)
    return null;
List<E> newlist = new ArrayList<E>();
int i = 0;
for (E item : objects) {
    if (i < n)
        newlist.add(item);
    else
...
TgetFirstNonNull(Collection c)
get First Non Null 
T ret = null;
Iterator<T> it = c.iterator();
while (it.hasNext() && ret == null) {
    T t = it.next();
    if (t != null)
        ret = t;
return ret;
...
TgetFirstNotNullValue(final Collection collection)
Returns the first not null element if the collection is not null and have not null value, else return null. 
if (isNotEmpty(collection)) {
    for (T element : collection) {
        if (element != null) {
            return element;
return null;
...
TgetFirstOrNull(final Collection collection)
Return either the first element when the collection is not null and empty or null. 
if (isEmpty(collection)) {
    return null;
if (collection instanceof List) {
    return ((List<T>) collection).get(0);
} else {
    return collection.iterator().next();
TgetFirstSortedItem(Collection items, T defaultValue)
get First Sorted Item 
List<T> sortedItems = new ArrayList<T>(items);
Collections.sort(sortedItems);
for (T item : sortedItems)
    return item;
return defaultValue;
intgetUnionSize(Collection firstCollection, Collection secondCollection)
Given two Collections, return the size of their union 
int firstSize = (firstCollection != null) ? firstCollection.size() : 0;
int secondSize = (secondCollection != null) ? secondCollection.size() : 0;
if (firstSize == 0)
    return secondSize;
if (secondSize == 0)
    return firstSize;
int size;
Collection<? extends E> iteratingCollection;
...
Collectionintersect(Collection firstSet, Collection secondSet)
intersect 
ArrayList result = new ArrayList();
Iterator it = firstSet.iterator();
while (it.hasNext()) {
    Object oj = it.next();
    if (secondSet.contains(oj)) {
        result.add(oj);
return result;