Uses of Package
java.util

Packages that use java.util

Package	Description
java.lang
java.lang.invoke
java.text
java.util
java.util.concurrent

Classes in java.util used by java.lang

Class and Description
Comparator A Comparator is used to compare two objects to determine their ordering with respect to each other.
Iterator An Iterator is used to sequence over a collection of objects.
Locale

Classes in java.util used by java.lang.invoke

Class and Description
List A List is a collection which maintains an ordering for its elements.

Classes in java.util used by java.text

Class and Description
Date The class Date represents a specific instant in time, with millisecond precision.
Hashtable Hashtable associates keys with values.

Classes in java.util used by java.util

Class and Description
AbstractCollection Class AbstractCollection is an abstract implementation of the Collection interface.
AbstractList AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access.
AbstractMap This class is an abstract implementation of the Map interface.
AbstractQueue AbstractQueue is an abstract class which implements some of the methods in Queue.
AbstractSequentialList AbstractSequentialList is an abstract implementation of the List interface.
AbstractSet An AbstractSet is an abstract implementation of the Set interface.
ArrayList ArrayList is an implementation of List, backed by an array.
BitSet The BitSet class implements a bit field.
Calendar Calendar is an abstract base class for converting between a Date object and a set of integer fields such as YEAR, MONTH, DAY, HOUR, and so on.
Collection Collection is the root of the collection hierarchy.
Comparator A Comparator is used to compare two objects to determine their ordering with respect to each other.
Date The class Date represents a specific instant in time, with millisecond precision.
Deque A kind of collection that can insert or remove element at both ends("double ended queue").
Dictionary Note: Do not use this class since it is obsolete.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
EventListener EventListener is the superclass of all event listener interfaces.
HashMap HashMap is an implementation of Map.
HashSet HashSet is an implementation of a Set.
Iterator An Iterator is used to sequence over a collection of objects.
List A List is a collection which maintains an ordering for its elements.
ListIterator An ListIterator is used to sequence over a List of objects.
Locale
Map A Map is a data structure consisting of a set of keys and values in which each key is mapped to a single value.
Map.Entry Map.Entry is a key/value mapping contained in a Map.
NavigableMap NavigableMap is a SortedMap with navigation methods answering the closest matches for specified item.
NavigableSet NavigableSet is a SortedSet with navigation methods answering the closest matches for specified item.
Observable Observable is used to notify a group of Observer objects when a change occurs.
Observer Observer is the interface to be implemented by objects that receive notification of updates on an Observable object.
PriorityQueue A PriorityQueue holds elements on a priority heap, which orders the elements according to their natural order or according to the comparator specified at construction time.
Queue This kind of collection provides advanced operations compared to basic collections, such as insertion, extraction, and inspection.
Random An instance of this class is used to generate a stream of pseudorandom numbers.
RandomAccess RandomAccess is implemented by List implementations that support fast (usually constant time) random access.
Set A Set is a data structure which does not allow duplicate elements.
SortedMap A map that has its keys ordered.
SortedSet SortedSet is a Set which iterates over its elements in a sorted order.
TimerTask
TimeZone TimeZone represents a time zone offset, and also figures out daylight savings.
Vector Vector is a variable size contiguous indexable array of objects.

Classes in java.util used by java.util.concurrent

Class and Description
Random An instance of this class is used to generate a stream of pseudorandom numbers.