Package org.apache.commons.collections

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
• ExtendedProperties - extends the Properties class to add extra functionality

Interface Summary

Interface	Description
Bag	Defines a collection that counts the number of times an object appears in the collection.
BidiMap	Defines a map that allows bidirectional lookup between key and values.
BoundedCollection	Defines a collection that is bounded in size.
BoundedMap	Defines a map that is bounded in size.
Buffer	Defines a collection that allows objects to be removed in some well-defined order.
Closure	Defines a functor interface implemented by classes that do something.
Factory	Defines a functor interface implemented by classes that create objects.
IterableMap	Defines a map that can be iterated directly without needing to create an entry set.
KeyValue	Defines a simple key value pair.
MapIterator	Defines an iterator that operates over a Map.
MultiMap	Defines a map that holds a collection of values against each key.
OrderedBidiMap	Defines a map that allows bidirectional lookup between key and values and retains and provides access to an ordering.
OrderedIterator	Defines an iterator that operates over an ordered collection.
OrderedMap	Defines a map that maintains order and allows both forward and backward iteration through that order.
OrderedMapIterator	Defines an iterator that operates over an ordered Map.
Predicate	Defines a functor interface implemented by classes that perform a predicate test on an object.
PriorityQueue	Deprecated. Replaced by the Buffer interface and implementations in buffer subpackage.
ResettableIterator	Defines an iterator that can be reset back to an initial state.
ResettableListIterator	Defines a list iterator that can be reset back to an initial state.
SortedBag	Defines a type of Bag that maintains a sorted order among its unique representative members.
SortedBidiMap	Defines a map that allows bidirectional lookup between key and values and retains both keys and values in sorted order.
Transformer	Defines a functor interface implemented by classes that transform one object into another.
Unmodifiable	Marker interface for collections, maps and iterators that are unmodifiable.

Class Summary

Class	Description
ArrayStack	An implementation of the Stack API that is based on an ArrayList instead of a Vector, so it is not synchronized to protect against multi-threaded access.
BagUtils	Provides utility methods and decorators for Bag and SortedBag instances.
BeanMap	Deprecated. Identical class now available in commons-beanutils (full jar version).
BinaryHeap	Deprecated. Replaced by PriorityBuffer in buffer subpackage.
BoundedFifoBuffer	Deprecated. Moved to buffer subpackage.
BufferUtils	Provides utility methods and decorators for Buffer 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.
CursorableLinkedList	Deprecated. Use new version in list subpackage, which has been rewritten and now returns the cursor from the listIterator method.
DefaultMapBag	Deprecated. Moved to bag subpackage as AbstractMapBag.
DefaultMapEntry	Deprecated. Use the version in the keyvalue subpackage.
DoubleOrderedMap	Deprecated. Replaced by TreeBidiMap in bidimap subpackage.
EnumerationUtils	Provides utility methods for Enumeration instances.
ExtendedProperties	This class extends normal Java properties by adding the possibility to use the same key many times concatenating the value strings instead of overwriting them.
FactoryUtils	FactoryUtils provides reference implementations and utilities for the Factory functor interface.
FastArrayList	A customized implementation of java.util.ArrayList designed to operate in a multithreaded environment where the large majority of method calls are read-only, instead of structural changes.
FastHashMap	A customized implementation of java.util.HashMap designed to operate in a multithreaded environment where the large majority of method calls are read-only, instead of structural changes.
FastTreeMap	A customized implementation of java.util.TreeMap designed to operate in a multithreaded environment where the large majority of method calls are read-only, instead of structural changes.
HashBag	Deprecated. Moved to bag subpackage and rewritten internally.
IteratorUtils	Provides static utility methods and decorators for Iterator instances.
ListUtils	Provides utility methods and decorators for List instances.
LRUMap	Deprecated. Moved to map subpackage.
MapUtils	Provides utility methods and decorators for Map and SortedMap instances.
MultiHashMap	Deprecated. Class now available as MultiValueMap in map subpackage.
PredicateUtils	PredicateUtils provides reference implementations and utilities for the Predicate functor interface.
ProxyMap	Deprecated. Moved to map subpackage as AbstractMapDecorator.
ReferenceMap	Deprecated. Moved to map subpackage.
SequencedHashMap	Deprecated. Replaced by LinkedMap and ListOrderedMap in map subpackage.
SetUtils	Provides utility methods and decorators for Set and SortedSet instances.
StaticBucketMap	Deprecated. Moved to map subpackage.
SynchronizedPriorityQueue	Deprecated. PriorityQueue is replaced by the Buffer interface, see buffer subpackage.
TransformerUtils	TransformerUtils provides reference implementations and utilities for the Transformer functor interface.
TreeBag	Deprecated. Moved to bag subpackage and rewritten internally.
UnboundedFifoBuffer	Deprecated. Moved to buffer subpackage.

Exception Summary

Exception	Description
BufferOverflowException	The BufferOverflowException is used when the buffer's capacity has been exceeded.
BufferUnderflowException	The BufferUnderflowException is used when the buffer is already empty.
FunctorException	Runtime exception thrown from functors.