Packages 
Package Description
org.apache.commons.collections4
This package contains the interfaces and utilities shared across all the subpackages of this component.
org.apache.commons.collections4.bag
This package contains implementations of the Bag and SortedBag interfaces.
org.apache.commons.collections4.bidimap
This package contains implementations of the BidiMap, OrderedBidiMap and SortedBidiMap interfaces.
org.apache.commons.collections4.collection
This package contains implementations of the Collection interface.
org.apache.commons.collections4.comparators
This package contains implementations of the Comparator interface.
org.apache.commons.collections4.functors
This package contains implementations of the Closure, Predicate, Transformer and Factory interfaces.
org.apache.commons.collections4.iterators
This package contains implementations of the Iterator interface.
org.apache.commons.collections4.keyvalue
This package contains implementations of collection and map related key/value classes.
org.apache.commons.collections4.list
This package contains implementations of the List interface.
org.apache.commons.collections4.map
This package contains implementations of the Map, IterableMap, OrderedMap and SortedMap interfaces.
org.apache.commons.collections4.multimap
This package contains implementations of the MultiValuedMap interfaces.
org.apache.commons.collections4.multiset
This package contains implementations of the MultiSet interface.
org.apache.commons.collections4.properties
This package contains classes to extend or customize the behavior of Properties.
org.apache.commons.collections4.queue
This package contains implementations for the Queue interface.
org.apache.commons.collections4.sequence
This package provides classes to compare two sequences of objects.
org.apache.commons.collections4.set
This package contains implementations of the Set, SortedSet and NavigableSet interfaces.
org.apache.commons.collections4.splitmap
The "split map" concept is that of an object that implements the Put and Get interfaces, with differing generic types.
org.apache.commons.collections4.trie
This package contains implementations of the Trie interface.
org.apache.commons.collections4.trie.analyzer
This package contains various KeyAnalyzer implementations.