Java Utililty Methods Collection First

List of utility methods to do Collection First

  1. HOME
  2. Java
  3. C
  4. Collection First

Description

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

Method

TnullSafeFirstElement(Collection collection)
null Safe First Element 
try {
    return collection.iterator().next();
} catch (Exception e) {
    return null;
ListremoveFirst(Collection collection, int numToRemove)
Removes and returns the first n items from the given collection. 
int toRemove = Math.min(collection.size(), numToRemove);
List removed = new ArrayList(toRemove);
Iterator iter = collection.iterator();
for (int idx = 0; idx < toRemove; idx++) {
    removed.add(iter.next());
    iter.remove();
return removed;
...
CollectionremoveFirst(Collection c)
remove First 
List<X> list;
if (c == null || c.size() == 0) {
    list = Collections.emptyList();
} else {
    list = new ArrayList<X>(c);
    list.remove(0);
return list;
...
Collectionsub(Collection coll, int first, int size)
sub 
if (coll == null) {
    return null;
if (coll.size() < size && first == 0) {
    return coll;
} else {
    List sub = new ArrayList(size);
    int i = -1;
...
Collectionsubtract(Collection firstCollection, Collection secondCollection)
subtract 
Collection collection = new ArrayList<>();
for (Object object : firstCollection) {
    if (!secondCollection.contains(object)) {
        collection.add(object);
return collection;
Collectionunion(Collection firstSet, Collection secondSet)
union 
return null;