Overview | Package | Class | Use | Tree | Deprecated | Index | Help
| JavaTM 2 Platform Standard Ed. 5.0
PREV PACKAGE NEXT PACKAGE | FRAMES NO FRAMES

## 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<E> | The root interface in the collection hierarchy.
Comparator<T> | A comparison function, which imposes a total ordering on some collection of objects.
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.
Formattable | The `Formattable` interface must be implemented by any class that needs to perform custom formatting using the `'s'` conversion specifier of `Formatter`.
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).
Observer | A class can implement the `Observer` interface when it wants to be informed of changes in observable objects.
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.
SortedMap<K,V> | 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<E> | 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<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.
ArrayList<E> | 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 | 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.
Currency | Represents a currency.
Date | The class `Date` represents a specific instant in time, with millisecond precision.
Dictionary<K,V> | The `Dictionary` class is the abstract parent of any class, such as `Hashtable`, which maps keys to values.
EnumMap<K extends Enum<K>,V> | A specialized `Map` implementation for use with enum type keys.
EnumSet<E extends Enum<E>> | A specialized `Set` implementation for use with enum types.
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.
FormattableFlags | FomattableFlags are passed to the `Formattable.formatTo()` method and modify the output format for Formattables.
Formatter | An interpreter for printf-style format strings.
GregorianCalendar | `GregorianCalendar` is a concrete subclass of `Calendar` and provides the standard calendar system used by most of the world.
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.
IdentityHashMap<K,V> | This class implements the `Map` interface with a hash table, using reference-equality in place of object-equality when comparing keys (and 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> | 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.
PriorityQueue<E> | An unbounded priority queue based on a priority heap.
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.
Scanner | A simple text scanner which can parse primitive types and strings using regular expressions.
SimpleTimeZone | `SimpleTimeZone` is a concrete subclass of `TimeZone` that represents a time zone for use with a Gregorian calendar.
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.
TreeMap<K,V> | Red-Black tree based implementation of the `SortedMap` interface.
TreeSet<E> | This class implements the `Set` interface, backed by a `TreeMap` instance.
UUID | A class that represents an immutable universally unique identifier (UUID).
Vector<E> | The `Vector` class implements a growable array of objects.
WeakHashMap<K,V> | A hashtable-based `Map` implementation with weak keys.

Enum Summary
Formatter.BigDecimalLayoutForm |

Exception Summary
ConcurrentModificationException | This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.
DuplicateFormatFlagsException | Unchecked exception thrown when duplicate flags are provided in the format specifier.
EmptyStackException | Thrown by methods in the `Stack` class to indicate that the stack is empty.
FormatFlagsConversionMismatchException | Unchecked exception thrown when a conversion and flag are incompatible.
FormatterClosedException | Unchecked exception thrown when the formatter has been closed.
IllegalFormatCodePointException | Unchecked exception thrown when a character with an invalid Unicode code point as defined by `Character.isValidCodePoint(int)` is passed to the `Formatter`.
IllegalFormatConversionException | Unchecked exception thrown when the argument corresponding to the format specifier is of an incompatible type.
IllegalFormatException | Unchecked exception thrown when a format string contains an illegal syntax or a format specifier that is incompatible with the given arguments.
IllegalFormatFlagsException | Unchecked exception thrown when an illegal combination flags is given.
IllegalFormatPrecisionException | Unchecked exception thrown when the precision is a negative value other than `-1`, the conversion does not support a precision, or the value is otherwise unsupported.
IllegalFormatWidthException | Unchecked exception thrown when the format width is a negative value other than `-1` or is otherwise unsupported.
InputMismatchException | Thrown by a `Scanner` to indicate that the token retrieved does not match the pattern for the expected type, or that the token is out of range for the expected type.
InvalidPropertiesFormatException | Thrown to indicate that an operation could not complete because the input did not conform to the appropriate XML document type for a collection of properties, as per the `Properties` specification.
MissingFormatArgumentException | Unchecked exception thrown when there is a format specifier which does not have a corresponding argument or if an argument index refers to an argument that does not exist.
MissingFormatWidthException | Unchecked exception thrown when the format width is required.
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.
UnknownFormatConversionException | Unchecked exception thrown when an unknown conversion is given.
UnknownFormatFlagsException | Unchecked exception thrown when an unknown flag is given.

## 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

- Collections Framework Overview
- Collections Framework Annotated Outline

## Related Documentation

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

- Collections Framework Tutorial
- Collections Framework Design FAQ

Since:
  JDK1.0

Overview | Package | Class | Use | Tree | Deprecated | Index | Help
| JavaTM 2 Platform Standard Ed. 5.0
PREV PACKAGE NEXT PACKAGE | FRAMES NO FRAMES

Submit a bug or feature
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.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.