Package java.util

Contains the collections framework, legacy collection classes, event model, date and time facilities, random-number generator, and miscellaneous utility classes.

See: Description

Interface Summary

Interface	Description
Collection<E>	The root interface in the collection hierarchy.
Comparator<T>	A comparison function, which imposes a total ordering on some collection of objects.
Deque<E>	A linear collection that supports element insertion and removal at both ends.
Enumeration<E>	An object that implements the Enumeration interface generates a series of elements, one at a time.
EventListener	A tagging interface that all event listener interfaces must extend.
Iterator<E>	An iterator over a collection.
List<E>	An ordered collection (also known as a sequence).
ListIterator<E>	An iterator for lists that allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the iterator's current position in the list.
Map<K,V>	An object that maps keys to values.
Map.Entry<K,V>	A map entry (key-value pair).
Queue<E>	A collection designed for holding elements prior to processing.
RandomAccess	Marker interface used by List implementations to indicate that they support fast (generally constant time) random access.
Set<E>	A collection that contains no duplicate elements.

Class Summary

Class	Description
AbstractCollection<E>	This class provides a skeletal implementation of the Collection interface, to minimize the effort required to implement this interface.
AbstractList<E>	This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "random access" data store (such as an array).
AbstractMap<K,V>	This class provides a skeletal implementation of the Map interface, to minimize the effort required to implement this interface.
AbstractQueue<E>	This class provides skeletal implementations of some Queue operations.
AbstractSequentialList<E>	This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "sequential access" data store (such as a linked list).
AbstractSet<E>	This class provides a skeletal implementation of the Set interface to minimize the effort required to implement this interface.
ArrayDeque<E>	Resizable-array implementation of the Deque interface.
ArrayList<E>	Resizable-array implementation of the List interface.
Arrays	This class contains various methods for manipulating arrays (such as sorting and searching).
Calendar	The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Collections	This class consists exclusively of static methods that operate on or return collections.
Date	The class Date represents a specific instant in time, with millisecond precision.
EventObject	The root class from which all event state objects shall be derived.
Formatter	An interpreter for printf-style format strings.
HashMap<K,V>	Hash table based implementation of the Map interface.
HashSet<E>	This class implements the Set interface, backed by a hash table (actually a HashMap instance).
Hashtable<K,V>	This class implements a hashtable, which maps keys to values.
LinkedHashMap<K,V>	Hash table and linked list implementation of the Map interface, with predictable iteration order.
LinkedHashSet<E>	Hash table and linked list implementation of the Set interface, with predictable iteration order.
LinkedList<E>	Doubly-linked list implementation of the List and Deque interfaces.
Objects	This class consists of static utility methods for operating on objects.
Properties	The Properties class represents a persistent set of properties.
PropertyPermission	This class is for property permissions.
Random	An instance of this class is used to generate a stream of pseudorandom numbers.
ServiceLoader<S>	A simple service-provider loading facility.
Stack<E>	The Stack class represents a last-in-first-out (LIFO) stack of objects.
StringTokenizer	The string tokenizer class allows an application to break a string into tokens.
Timer	A facility for threads to schedule tasks for future execution in a background thread.
TimerTask	A task that can be scheduled for one-time or repeated execution by a Timer.
TimeZone	TimeZone represents a time zone offset, and also figures out daylight savings.
Vector<E>	The Vector class implements a growable array of objects.
WeakHashMap<K,V>	Hash table based implementation of the Map interface, with weak keys.

Exception Summary

Exception	Description
ConcurrentModificationException	This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.
EmptyStackException	Thrown by methods in the Stack class to indicate that the stack is empty.
NoSuchElementException	Thrown by various accessor methods to indicate that the element being requested does not exist.

Error Summary

Error	Description
ServiceConfigurationError	Error thrown when something goes wrong while loading a service provider.

Package java.util Description

Contains the collections framework, legacy collection classes, event model, date and time facilities, random-number generator, and miscellaneous utility classes.

Package Specification

• Java Collections Framework.
• Collections Framework Annotated Outline

Since:

JDK1.0