Package java.util

Interface Summary

Interface	Description
Collection<E>	Collection is the root of the collection hierarchy.
Comparator<T>	A Comparator is used to compare two objects to determine their ordering with respect to each other.
Deque<E>	A kind of collection that can insert or remove element at both ends("double ended queue").
Enumeration<T>	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.
Iterator<E>	An Iterator is used to sequence over a collection of objects.
List<E>	A List is a collection which maintains an ordering for its elements.
ListIterator<E>	An ListIterator is used to sequence over a List of objects.
Map<K,V>	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<K,V>	Map.Entry is a key/value mapping contained in a Map.
NavigableMap<K,V>	NavigableMap is a SortedMap with navigation methods answering the closest matches for specified item.
NavigableSet<E>	NavigableSet is a SortedSet with navigation methods answering the closest matches for specified item.
Observer	Observer is the interface to be implemented by objects that receive notification of updates on an Observable object.
Queue<E>	This kind of collection provides advanced operations compared to basic collections, such as insertion, extraction, and inspection.
RandomAccess	RandomAccess is implemented by List implementations that support fast (usually constant time) random access.
Set<E>	A Set is a data structure which does not allow duplicate elements.
SortedMap<K,V>	A map that has its keys ordered.
SortedSet<E>	SortedSet is a Set which iterates over its elements in a sorted order.

Class Summary

Class	Description
AbstractCollection<E>	Class AbstractCollection is an abstract implementation of the Collection interface.
AbstractList<E>	AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access.
AbstractMap<K,V>	This class is an abstract implementation of the Map interface.
AbstractMap.SimpleEntry<K,V>	A key-value mapping.
AbstractMap.SimpleImmutableEntry<K,V>	An immutable key-value mapping.
AbstractQueue<E>	AbstractQueue is an abstract class which implements some of the methods in Queue.
AbstractSequentialList<E>	AbstractSequentialList is an abstract implementation of the List interface.
AbstractSet<E>	An AbstractSet is an abstract implementation of the Set interface.
ArrayDeque<E>	An implementation of Deque, backed by an array.
ArrayList<E>	ArrayList is an implementation of List, backed by an array.
Arrays	Arrays contains static methods which operate on arrays.
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.
Collections	Collections contains static methods which operate on Collection classes.
Date	The class Date represents a specific instant in time, with millisecond precision.
Dictionary<K,V>	Note: Do not use this class since it is obsolete.
EventListenerProxy	This abstract class provides a simple wrapper for objects of type EventListener.
HashMap<K,V>	HashMap is an implementation of Map.
HashSet<E>	HashSet is an implementation of a Set.
Hashtable<K,V>	Hashtable associates keys with values.
IdentityHashMap<K,V>	IdentityHashMap is a variant on HashMap which tests equality by reference instead of equality by value.
LinkedHashMap<K,V>	LinkedHashMap is a variant of HashMap.
LinkedHashSet<E>	LinkedHashSet is a variant of HashSet.
LinkedList<E>	LinkedList is an implementation of List, backed by a linked list.
Locale
Objects	This is a compatibility class which supports the java.util.Objects API.
Observable	Observable is used to notify a group of Observer objects when a change occurs.
PriorityQueue<E>	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.
Random	An instance of this class is used to generate a stream of pseudorandom numbers.
Stack<E>	Stack is a Last-In/First-Out(LIFO) data structure which represents a stack of objects.
StringTokenizer	The StringTokenizer class allows an application to break a string into tokens by performing code point comparison.
Timer
TimerTask
TimeZone	TimeZone represents a time zone offset, and also figures out daylight savings.
TreeMap<K,V>	TreeMap is an implementation of SortedMap.
TreeSet<E>	TreeSet is an implementation of SortedSet.
Vector<E>	Vector is a variable size contiguous indexable array of objects.

Exception Summary

Exception	Description
ConcurrentModificationException	An ConcurrentModificationException is thrown when a Collection is modified and an existing iterator on the Collection is used to modify the Collection as well.
EmptyStackException	Thrown by methods in the Stack class to indicate that the stack is empty.
NoSuchElementException	Thrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration.