Java Utililty Methods Collection Intersect

List of utility methods to do Collection Intersect

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

Description

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

Method

Setintersect(Collection... collections)
Returns the intersection set of a series of input collections. 
if (collections.length == 0)
    return new LinkedHashSet<A>();
Set<A> intersectionSet = new LinkedHashSet<A>();
intersectionSet.addAll(collections[0]);
for (int i = 1; i < collections.length; i++) {
    intersectionSet.retainAll(collections[i]);
return intersectionSet;
...
Listintersect(Collection a, Collection b)
Returns a copy of a containing only elements also in b . 
List<T> result = new ArrayList<>();
for (T t : a) {
    if (b.contains(t)) {
        result.add(t);
return Collections.unmodifiableList(result);
Collectionintersect(Collection collA, Collection collB, Collection target)
return a new Collection with the elements which appear both in a and b.
Complexity: for sets - linear, for lists - quadratic. 
target.clear();
for (T elem : collA) {
    if (collB.contains(elem)) {
        target.add(elem);
return target;
Collectionintersect(Collection collection1, Collection collection2)
Given two collections of elements of type , return a collection with the items which only appear in both lists 
if (isEmpty(collection1) || isEmpty(collection2)) {
    return Collections.emptyList();
Set<T> intersection = new HashSet<T>(collection1);
intersection.retainAll(collection2);
return intersection;
booleanintersect(Collection t1, Collection t2)
intersect 
for (T t : t1) {
    if (t2.contains(t)) {
        return true;
return false;
CollectionintersectCollections(Collection collection1, Collection collection2)
Returns all items that are both in collection1 and in collection2 
Collection<T> result = new ArrayList<T>(collection1);
result.retainAll(collection2);
return result;
booleanintersectingCollections(Collection collection1, Collection collection2)
intersecting Collections 
if (collection1 == null || collection2 == null) {
    return false;
int size1 = collection1.size();
int size2 = collection2.size();
if (size1 < size2) {
    for (Object obj : collection1)
        if (collection2.contains(obj)) {
...
CintersectInto(C into, Collection... from)
intersect Into 
if (from.length > 0) {
    into.addAll(from[0]);
    for (int i = 1; i < from.length; i++) {
        into.retainAll(from[i]);
return into;
Setintersection(Collection> coll)
Returns the intersection of all the collections given in a collection. 
Iterator<? extends Collection<? extends T>> i = coll.iterator();
if (!i.hasNext())
    return new HashSet<T>();
Set<T> set = new HashSet<T>(i.next());
while (i.hasNext()) {
    Collection<? extends T> innerColl = i.next();
    set.retainAll(innerColl);
return set;
Collectionintersection(Collection a, Collection b)
intersection 
Collection results = new HashSet();
for (Iterator i = a.iterator(); i.hasNext();) {
    Object o = i.next();
    if (b.contains(o)) {
        results.add(o);
return results;
...