ApacheCommonCollectionsEquivalents

Apache Commons Collections Equivalents

CollectionUtils (source)

CollectionUtils	Guava
void addAll(Collection, Enumeration)	Iterators.addAll(collection, Iterators.forEnumeration(enumeration))
void addAll(Collection, Iterator)	Iterators.addAll(collection, iterator)
void addAll(Collection, Object[])	Collections.addAll(collection, array) (JDK)
boolean addIgnoreNull(Collection, Object)	if (o != null) { collection.add(o); }
int cardinality(Object, Collection)	Iterables.frequency(collection, object)
Collection collect(Collection, Transformer)	newArrayList(Collections2.transform(input, function))
Collection collect(Collection, Transformer, Collection)	output.addAll(Collections2.transform(input, function))
Collection collect(Iterator, Transformer)	newArrayList(Iterators.transform(input, function))
Collection collect(Iterator, Transformer, Collection)	Iterators.addAll(output, Iterators.transform(input, function))
boolean containsAny(Collection coll1, Collection coll2)	!Collections.disjoint(coll1, coll2) (JDK)
int countMatches(Collection, Predicate)	Iterables.size(Iterables.filter(collection, predicate))
Collection disjunction(Collection, Collection)	Sets.symmetricDifference(set1, set2)
boolean exists(Collection, Predicate)	Iterables.any(collection, predicate)
void filter(Collection, Predicate)	Iterables.removeIf(collection, not(predicate)) (see also Iterables.transform, which creates a view instead of mutating the input)
Object find(Collection, Predicate)	Iterables.find(collection, predicate)
void forAllDo(Collection, Closure)	for (Object o : collection) { closure.execute(o); }
Object get(Object, int)	Iterables.get(o, index), supplemented with calls to entrySet(), forEnumeration(), etc.
Map getCardinalityMap(Collection)	ImmutableMultiset.copyOf(collection)
Object index(Object, int)	Iterables.get(o, index), supplemented with calls to keySet(), forEnumeration(), etc.
Object index(Object, Object)	Iterables.get(o, index), supplemented with calls to entrySet(), forEnumeration(), etc.
Collection intersection(Collection, Collection)	Sets/Multisets.intersection(a, b)
boolean isEmpty(Collection)	collection == null
boolean isEqualCollection(Collection, Collection)	If both are Sets or Multisets, use equals(); otherwise ImmutableMultiset.copyOf(a).equals(ImmutableMultiset.copyOf(b)
boolean isFull(Collection)	No equivalent--no BoundedCollection type.
boolean isNotEmpty(Collection)	collection != null && !collection.isEmpty()
boolean isProperSubCollection(Collection, Collection)	No equivalent--check that a.size() < b.size() and then use the check described below.
boolean isSubCollection(Collection, Collection)	Multisets.containsOccurrences(ImmutableMultiset.copyOf(coll1), ImmutableMultiset.copyOf(coll2))
int maxSize(Collection)	No equivalent--no BoundedCollection type.
Collection predicatedCollection(Collection, Predicate)	Constraints.constrainedCollection/List/Set/etc.
Collection removeAll(Collection, Collection)	newArrayList(Iterables.filter(collection, Predicates.not(Predicates.in(remove))))
Collection retainAll(Collection, Collection)	newArrayList(Iterables.filter(collection, Predicates.in(retain)))
void reverseArray(Object[])	Lists.reverse(Arrays.asList(array)) (returns an inverse List view without modifying array)
Collection select(Collection, Predicate)	newArrayList(Iterables.filter(collection, predicate))
void select(Collection, Predicate, Collection)	Iterables.addAll(output, Iterables.filter(input, predicate))
Collection selectRejected(Collection, Predicate)	newArrayList(Iterables.filter(collection, Predicates.not(predicate)))
void selectRejected(Collection, Predicate, Collection)	Iterables.addAll(output, Iterables.filter(input, Predicates.not(predicate)))
int size(Object)	Collection/Map.size(), array.length, Iterables/Iterators.size (with forEnumeration() if necessary)
boolean sizeIsEmpty(Object)	Collection/Map.isEmpty(), array.length == 0, Iterables/Iterators.isEmpty (with forEnumeration() if necessary)
Collection subtract(Collection, Collection)	No equivalent--create an ArrayList containing a and then call remove on it for each element in b.
Collection synchronizedCollection(Collection)	Collections.synchronizedCollection(collection) (JDK)
void transform(Collection, Transformer)	No equivalent for transforming a Collection in place... not very useful. Prefer transformed views (Lists/Collections2.transform) or copies of them.
Collection transformedCollection(Collection, Transformer)	No equivalent for transforming Objects that are added to a Collection... a ForwardingCollection could easily handle this, though.
Collection typedCollection(Collection, Class)	Collections.checkedCollection/Set/List/etc. (JDK)
Collection union(Collection, Collection)	Sets.union(a, b)
Collection unmodifiableCollection(Collection)	Collections.unmodifiableCollection/Set/List/etc. (JDK) Consider ImmutableCollection types if you want immutability.