Package org.apache.commons.collections4

This package contains the interfaces and utilities shared across all the subpackages of this component.

The following collection implementations are provided in the package:

• ArrayStack - a non synchronized Stack that follows the same API as java.util Stack

Interface Summary

Interface	Description
Bag<E>	Defines a collection that counts the number of times an object appears in the collection.
BidiMap<K,V>	Defines a map that allows bidirectional lookup between key and values.
BoundedCollection<E>	Defines a collection that is bounded in size.
BoundedMap<K,V>	Defines a map that is bounded in size.
Closure<T>	Defines a functor interface implemented by classes that do something.
Equator<T>	An equation function, which determines equality between objects of type T.
Factory<T>	Defines a functor interface implemented by classes that create objects.
Get<K,V>	The "read" subset of the Map interface.
IterableGet<K,V>	The "read" subset of the Map interface.
IterableMap<K,V>	Defines a map that can be iterated directly without needing to create an entry set.
IterableSortedMap<K,V>	SortedMap + OrderedMap.
KeyValue<K,V>	Defines a simple key value pair.
ListValuedMap<K,V>	Defines a map that holds a list of values against each key.
MapIterator<K,V>	Defines an iterator that operates over a Map.
MultiMap<K,V>	Deprecated. since 4.1, use MultiValuedMap instead
MultiSet<E>	Defines a collection that counts the number of times an object appears in the collection.
MultiSet.Entry<E>	An unmodifiable entry for an element and its occurrence as contained in a MultiSet.
MultiValuedMap<K,V>	Defines a map that holds a collection of values against each key.
OrderedBidiMap<K,V>	Defines a map that allows bidirectional lookup between key and values and retains and provides access to an ordering.
OrderedIterator<E>	Defines an iterator that operates over an ordered container.
OrderedMap<K,V>	Defines a map that maintains order and allows both forward and backward iteration through that order.
OrderedMapIterator<K,V>	Defines an iterator that operates over an ordered Map.
Predicate<T>	Defines a functor interface implemented by classes that perform a predicate test on an object.
Put<K,V>	The "write" subset of the Map interface.
ResettableIterator<E>	Defines an iterator that can be reset back to an initial state.
ResettableListIterator<E>	Defines a list iterator that can be reset back to an initial state.
SetValuedMap<K,V>	Defines a map that holds a set of values against each key.
SortedBag<E>	Defines a type of Bag that maintains a sorted order among its unique representative members.
SortedBidiMap<K,V>	Defines a map that allows bidirectional lookup between key and values and retains both keys and values in sorted order.
Transformer<I,O>	Defines a functor interface implemented by classes that transform one object into another.
Trie<K,V>	Defines the interface for a prefix tree, an ordered tree data structure.
Unmodifiable	Marker interface for collections, maps and iterators that are unmodifiable.

Class Summary

Class	Description
ArrayStack<E>	Deprecated. use ArrayDeque instead (available from Java 1.6)
BagUtils	Provides utility methods and decorators for Bag and SortedBag instances.
ClosureUtils	ClosureUtils provides reference implementations and utilities for the Closure functor interface.
CollectionUtils	Provides utility methods and decorators for Collection instances.
ComparatorUtils	Provides convenient static utility methods for Comparator objects.
EnumerationUtils	Provides utility methods for Enumeration instances.
FactoryUtils	FactoryUtils provides reference implementations and utilities for the Factory functor interface.
FluentIterable<E>	A FluentIterable provides a powerful yet simple API for manipulating Iterable instances in a fluent manner.
IterableUtils	Provides utility methods and decorators for Iterable instances.
IteratorUtils	Provides static utility methods and decorators for Iterator instances.
ListUtils	Provides utility methods and decorators for List instances.
MapUtils	Provides utility methods and decorators for Map and SortedMap instances.
MultiMapUtils	Provides utility methods and decorators for MultiValuedMap instances.
MultiSetUtils	Provides utility methods and decorators for MultiSet instances.
PredicateUtils	PredicateUtils provides reference implementations and utilities for the Predicate functor interface.
QueueUtils	Provides utility methods and decorators for Queue instances.
SetUtils	Provides utility methods and decorators for Set and SortedSet instances.
SetUtils.SetView<E>	An unmodifiable view of a set that may be backed by other sets.
SplitMapUtils	Utilities for working with "split maps:" objects that implement Put and/or Get but not Map.
TransformerUtils	TransformerUtils provides reference implementations and utilities for the Transformer functor interface.
TrieUtils	A collection of Trie utilities.

Exception Summary

Exception	Description
FunctorException	Runtime exception thrown from functors.