ApacheCommonCollectionsEquivalents

CollectionUtils (source)

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 || collection.isEmpty()

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.

Additions

I can't find a way to make the Wiki world-writable, so post any additions as comments. I'll check for new ones every so often and approve their authors as Wiki editors.