Java Utililty Methods List Intersect

List<? extends T> smaller = list1;
List<? extends T> larger = list2;
if (list1.size() > list2.size()) {
    smaller = list2;
    larger = list1;
List<T> newSmaller = new ArrayList<T>(smaller);
List<T> result = new ArrayList<T>(smaller.size());
...

if (sets.isEmpty())
    return Collections.emptySet();
Set<T> accum = new HashSet<>();
accum.addAll(sets.get(0));
for (int i = 1; i < sets.size(); i++) {
    accum = intersection(accum, sets.get(i));
return accum;
...

list1.retainAll(list2);
return list1;

if (list1 == null || list2 == null)
    throw new NullPointerException("Not initizalized lists");
List<E> intersection = new LinkedList<E>();
E item;
ListIterator<E> iter = list1.listIterator();
while (iter.hasNext()) {
    item = iter.next();
    if (list2.contains(item)) {
...

List<Integer> C = new ArrayList<Integer>();
for (Integer i : a) {
    if (b.contains(i)) {
        C.add(i);
return C;

List<String> intersection = new ArrayList<String>();
for (String s : list1) {
    if (list2.contains(s)) {
        intersection.add(s);
return intersection.size();

List<T> _intersect = new ArrayList<T>();
for (int i = 0; i < arrayOne.size(); i++) {
    for (int j = 0; j < arrayTwo.size(); j++) {
        if (arrayOne.get(i) == arrayTwo.get(j)) {
            _intersect.add(arrayOne.get(i));
return _intersect;

ArrayList<T> onlyInOne = new ArrayList<T>(listOne);
onlyInOne.removeAll(listTwo);
ArrayList<T> inBoth = new ArrayList<T>(listOne);
inBoth.removeAll(onlyInOne);
return inBoth;

List<T> intSet = new ArrayList<T>(set1);
intSet.retainAll(set2);
return intSet;

List<T> tmp = intersection(list1, list2);
if (tmp.size() == list2.size() && tmp.size() == list1.size())
    return 1;
if (tmp.size() < list2.size() && tmp.size() == list1.size())
    return 2;
if (tmp.size() < list1.size() && tmp.size() == list2.size())
    return 5;
if (tmp.size() > 0)
...