Package java.util

Utility classes such as collections (maps, sets, lists, dictionaries and stacks), calendars, dates, locales, properties, timers, resource bundles and event objects.

Interface Summary

Collection<E> Interface that represents a collection of objects.
Comparator<T> Interface for objects that specify an ordering between objects.
Deque<E> A linear collection that supports element insertion and removal at both ends.
Enumeration<E> Interface for lists of objects that can be returned in sequence.
EventListener Empty interface that is implemented by classes that need to receive events.
Formattable The Formattable interface is used to provide customised formatting to arbitrary objects via the Formatter.
Iterator<E> An object which iterates over a collection.
List<E> An ordered collection (also known as a list).
ListIterator<E> An extended version of Iterator to support the extra features of Lists.
Map<K,V> An object that maps keys onto values.
Map.Entry<K,V> A map entry (key-value pair).
NavigableMap<K,V> A SortedMap extended with navigation methods returning the closest matches for given search targets.
NavigableSet<E> A SortedSet extended with navigation methods reporting closest matches for given search targets.
Observer Interface that is implemented when a class wants to be informed of changes in Observable objects.
Queue<E> A collection designed for holding elements prior to processing.
RandomAccess Marker interface used to inform List implementations that they support fast (usually constant time) random access.
Set<E> A collection that contains no duplicates.
SortedMap<K,V> A map which guarantees its key's iteration order.
SortedSet<E> A set which guarantees its iteration order.

Class Summary

AbstractCollection<E> A basic implementation of most of the methods in the Collection interface to make it easier to create a collection.
AbstractList<E> A basic implementation of most of the methods in the List interface to make it easier to create a List based on a random-access data structure.
AbstractMap<K,V> An abstract implementation of Map to make it easier to create your own implementations.
AbstractMap.SimpleEntry<K,V> A class which implements Map.Entry.
AbstractMap.SimpleImmutableEntry<K,V> A class containing an immutable key and value.
AbstractQueue<E> This class provides skeletal implementations of some Queue operations.
AbstractSequentialList<E> Abstract superclass to make it easier to implement the List interface when backed by a sequential-access store, such as a linked list.
AbstractSet<E> An abstract implementation of Set to make it easier to create your own implementations.
ArrayDeque<E> Resizable-array implementation of the Deque interface.
ArrayList<E> An array-backed implementation of the List interface.
Arrays This class contains various static utility methods performing operations on arrays, and a method to provide a List "view" of an array to facilitate using arrays with Collection-based APIs.
BitSet This class can be thought of in two ways.
Calendar This class is an abstract base class for Calendars, which can be used to convert between Date objects and a set of integer fields which represent YEAR, MONTH, DAY, etc.
Collections Utility class consisting of static methods that operate on, or return Collections.
Currency Representation of a currency for a particular locale.
Date This class represents a specific time in milliseconds since the epoch.
Dictionary<K,V> A Dictionary maps keys to values; how it does that is implementation-specific.
EnumMap<K,extends,Enum,K,V>
EnumSet<T,extends,Enum,T> Provides an efficient mechanism for recording a set of enumeration constants.
EventListenerProxy An abstract wrapper for event listeners.
EventObject Represents Events fired by Objects.
FormattableFlags This class contains a set of flags used by the Formattable.formatTo() method.
Formatter A Java formatter for printf-style format strings, as seen in the C programming language.
Formatter.BigDecimalLayoutForm The type of numeric output format for a BigDecimal.
GregorianCalendar This class represents the Gregorian calendar, that is used in most countries all over the world.
HashMap<K,V> This class provides a hashtable-backed implementation of the Map interface.
HashSet<T> This class provides a HashMap-backed implementation of the Set interface.
Hashtable<K,V> A class which implements a hashtable data structure.
IdentityHashMap<K,V> This class provides a hashtable-backed implementation of the Map interface, but uses object identity to do its hashing.
LinkedHashMap<K,V> This class provides a hashtable-backed implementation of the Map interface, with predictable traversal order.
LinkedHashSet<T> This class provides a hashtable-backed implementation of the Set interface, with predictable traversal order.
LinkedList<T> Linked list implementation of the List interface.
ListResourceBundle A ListResouceBundle provides an easy way, to create your own resource bundle.
Locale Locales represent a specific country and culture.
Observable This class represents an object which is observable.
PriorityQueue<E>
Properties A set of persistent properties, which can be saved or loaded from a stream.
PropertyPermission This class represents the permission to access and modify a property.
The name is the name of the property, e.g. xxx.
PropertyResourceBundle This class is a concrete ResourceBundle that gets it resources from a property file.
Random This class generates pseudorandom numbers.
ResourceBundle A resource bundle contains locale-specific data.
Scanner
ServiceLoader<S> Facilities for loading service providers.
SimpleTimeZone This class represents a simple time zone offset and handles daylight savings.
Stack<T>
StringTokenizer This class splits a string into tokens.
Timer Timer that can run TimerTasks at a later time.
TimerTask Task that can be run at a later time if given to a Timer.
TimeZone This class represents a time zone offset and handles daylight savings.
TreeMap<K,V> This class provides a red-black tree implementation of the SortedMap interface.
TreeSet<T> This class provides a TreeMap-backed implementation of the SortedSet interface.
UUID This class represents a 128-bit UUID value.
Vector<T> The Vector classes implements growable arrays of Objects.
WeakHashMap<K,V> A weak hash map has only weak references to the key.

Exception Summary

ConcurrentModificationException Exception that is thrown by the collections classes when it is detected that a modification has been made to a data structure when this is not allowed, such as when a collection is structurally modified while an Iterator is operating over it.
DuplicateFormatFlagsException Thrown when the flags supplied to the Formatter.format() method of a Formatter contain duplicates.
EmptyStackException This exception is thrown by the Stack class when an attempt is made to pop or otherwise access elements from an empty stack.
FormatFlagsConversionMismatchException Thrown when the flags supplied to the Formatter.format() method of a Formatter contains a flag that does not match the conversion character specified for it.
FormatterClosedException Thrown when a method is called on a Formatter but it has already been closed.
IllegalFormatCodePointException Thrown when a Formatter receives a character with an invalid Unicode codepoint, as defined by Character.isValidCodePoint(int).
IllegalFormatConversionException Thrown when the type of an argument supplied to the Formatter.format() method of a Formatter does not match the conversion character specified for it.
IllegalFormatException A general exception thrown when a format string is supplied to a Formatter that contains either invalid syntax or a mismatch between the format specification and the supplied arguments.
IllegalFormatFlagsException Thrown when the flags supplied to the Formatter.format() method of a Formatter form an illegal combination.
IllegalFormatPrecisionException Thrown when the specified precision for a Formatter argument is illegal.
IllegalFormatWidthException Thrown when the specified width for a Formatter argument is illegal.
InputMismatchException Thrown when a Scanner instance encounters a mismatch between the input data and the pattern it is trying to match it against.
InvalidPropertiesFormatException
MissingFormatArgumentException Thrown when the a format specification for a Formatter refers to an argument that is non-existent, or an argument index references a non-existent argument.
MissingFormatWidthException Thrown when the a format specification for a Formatter does not include a width for a value where one is required.
MissingResourceException This exception is thrown when a resource is missing.
NoSuchElementException Exception thrown when an attempt is made to access an element that does not exist.
TooManyListenersException This exception is part of the java event model.
UnknownFormatConversionException Thrown when a Formatter is supplied with an unknown conversion.
UnknownFormatFlagsException Thrown when a Formatter is supplied with an unknown flag.

Error Summary

ServiceConfigurationError An error thrown when a problem occurs during the loading of a service provider by a ServiceLoader.
Utility classes such as collections (maps, sets, lists, dictionaries and stacks), calendars, dates, locales, properties, timers, resource bundles and event objects.