JavaTM 2 Platform
Std. Ed. v1.4.2

Package java.util

Contains the collections framework, legacy collection classes, event model, date and time facilities, internationalization, and miscellaneous utility classes (a string tokenizer, a random-number generator, and a bit array).

See:
          Description

Interface Summary
Collection The root interface in the collection hierarchy.
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Enumeration 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 An iterator over a collection.
List An ordered collection (also known as a sequence).
ListIterator 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 An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Observer A class can implement the Observer interface when it wants to be informed of changes in observable objects.
RandomAccess Marker interface used by List implementations to indicate that they support fast (generally constant time) random access.
Set A collection that contains no duplicate elements.
SortedMap A map that further guarantees that it will be in ascending key order, sorted according to the natural ordering of its keys (see the Comparable interface), or by a comparator provided at sorted map creation time.
SortedSet A set that further guarantees that its iterator will traverse the set in ascending element order, sorted according to the natural ordering of its elements (see Comparable), or by a Comparator provided at sorted set creation time.
 

Class Summary
AbstractCollection This class provides a skeletal implementation of the Collection interface, to minimize the effort required to implement this interface.
AbstractList 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 This class provides a skeletal implementation of the Map interface, to minimize the effort required to implement this interface.
AbstractSequentialList 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 This class provides a skeletal implementation of the Set interface to minimize the effort required to implement this interface.
ArrayList Resizable-array implementation of the List interface.
Arrays This class contains various methods for manipulating arrays (such as sorting and searching).
BitSet This class implements a vector of bits that grows as needed.
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 This class consists exclusively of static methods that operate on or return collections.
Currency Represents a currency.
Date The class Date represents a specific instant in time, with millisecond precision.
Dictionary The Dictionary class is the abstract parent of any class, such as Hashtable, which maps keys to values.
EventListenerProxy An abstract wrapper class for an EventListener class which associates a set of additional parameters with the listener.
EventObject The root class from which all event state objects shall be derived.
GregorianCalendar GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar used by most of the world.
HashMap Hash table based implementation of the Map interface.
HashSet This class implements the Set interface, backed by a hash table (actually a HashMap instance).
Hashtable This class implements a hashtable, which maps keys to values.
IdentityHashMap This class implements the Map interface with a hash table, using reference-equality in place of object-equality when comparing keys (and values).
LinkedHashMap Hash table and linked list implementation of the Map interface, with predictable iteration order.
LinkedHashSet Hash table and linked list implementation of the Set interface, with predictable iteration order.
LinkedList Linked list implementation of the List interface.
ListResourceBundle ListResourceBundle is an abstract subclass of ResourceBundle that manages resources for a locale in a convenient and easy to use list.
Locale A Locale object represents a specific geographical, political, or cultural region.
Observable This class represents an observable object, or "data" in the model-view paradigm.
Properties The Properties class represents a persistent set of properties.
PropertyPermission This class is for property permissions.
PropertyResourceBundle PropertyResourceBundle is a concrete subclass of ResourceBundle that manages resources for a locale using a set of static strings from a property file.
Random An instance of this class is used to generate a stream of pseudorandom numbers.
ResourceBundle Resource bundles contain locale-specific objects.
SimpleTimeZone SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar.
Stack 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.
TreeMap Red-Black tree based implementation of the SortedMap interface.
TreeSet This class implements the Set interface, backed by a TreeMap instance.
Vector The Vector class implements a growable array of objects.
WeakHashMap A hashtable-based Map implementation with weak keys.
 

Exception Summary
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.
MissingResourceException Signals that a resource is missing.
NoSuchElementException Thrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration.
TooManyListenersException The TooManyListenersException Exception is used as part of the Java Event model to annotate and implement a unicast special case of a multicast Event Source.
 

Package java.util Description

Contains the collections framework, legacy collection classes, event model, date and time facilities, internationalization, and miscellaneous utility classes (a string tokenizer, a random-number generator, and a bit array).

Package Specification

Related Documentation

For overviews, tutorials, examples, guides, and tool documentation, please see:

Since:
JDK1.0

JavaTM 2 Platform
Std. Ed. v1.4.2

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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