Package java.util

Provides an extensive set of utility classes.

See:
Description

Interface Summary

Collection	Collection is the root of the collection hierarchy.
Comparator	Comparator is used to compare two objects to determine their ordering in respect to each other.
Enumeration	An Enumeration is used to sequence over a collection of objects.
EventListener	EventListener is the superclass of all event listener interfaces.
Formattable	Any class that need to perform customer formatting by transferring converter specifier 's' to Formatter should implement the Formattable interface.
Iterator	An Iterator is used to sequence over a collection of objects.
List	List is a collection which maintains an ordering for its elements.
ListIterator	An ListIterator is used to sequence over a List of objects.
Map	Map has a set of keys, each key is mapped to a single value.
Map.Entry	Map.Entry is a key/value mapping which is contained in a Map.
Observer	Observer must be implemented by objects which are added to an Observable.
Queue	A kind of collection provides advanced operations than other basic collections, such as insertion, extraction, and inspection.
RandomAccess	RandomAccess is implemented by List implementations that support fast (usually constant time) random access.
Set	Set is a collection which does not allow duplicate elements.
SortedMap	SortedMap is a Map where the iterators sequence in order of the sorted keys.
SortedSet	SortedSet is a Set which iterates its elements in sorted order.

Class Summary

AbstractCollection	AbstractCollection is an abstract implementation of the Collection interface.
AbstractList	AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access.
AbstractMap	AbstractMap is an abstract implementation of the Map interface.
AbstractQueue	An abstract class which gives out skeletal implementations for some methods in Queue which include add, remove, and element that are based on offer, poll, and peek except that they throw exception to indicate the occurrence of some error instead of the return value of false or null.
AbstractSequentialList	AbstractSequentialList is an abstract implementation of the List interface.
AbstractSet	AbstractSet is an abstract implementation of the Set interface.
ArrayList	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 class which provides the conversion between Dates and integer calendar fields, such as the month, year or minute.
Collections	Collections contains static methods which operate on Collection classes.
Currency	This class represents a currency as identified in the ISO 4217 currency codes.
Date	Date represents a specific moment in time, to the millisecond.
Dictionary	Dictionary is a abstract class which is the superclass of all classes that associate keys with values, such as Hashtable.
EnumMap
EnumSet
EventListenerProxy	This abstract class provides a simple wrapper to types of EventListener.
EventObject	EventObjects represent events.
FormattableFlags	FormattableFlags are used as a parameter to method Formattable.formatTo() and instruct the output format in Formattables.
Formatter	The Formatter class is a String-formatting utility that is designed to work like the printf function of the C programming language.
Formatter.BigDecimalLayoutForm	The enumeration giving the available styles for formatting very large decimal numbers.
GregorianCalendar	GregorianCalendar provides the conversion between Dates and integer calendar fields, such as the month, year or minute, for the Gregorian calendar.
HashMap	HashMap is an implementation of Map.
HashSet	HashSet is an implementation of Set.
Hashtable	Hashtable associates keys with values.
IdentityHashMap	IdentityHashMap This is a variant on HashMap which tests equality by reference instead of by value.
LinkedHashMap	LinkedHashMap is a variant on HashMap.
LinkedHashSet	LinkedHashSet is a variant on HashSet.
LinkedList	LinkedList is an implementation of List, backed by a linked list.
ListResourceBundle	ListResourceBundle is the abstract superclass of classes which provide resources by implementing the getContents() method to return the list of resources.
Locale	Locale represents a language/country/variant combination.
Observable	Observable is used to notify a group of Observer objects when a change occurs.
PriorityQueue	PriorityQueue holds elements on a priority heap, which orders elements according to the comparator specified at construction or their natural order.
Properties	Properties is a Hashtable where the keys and values must be Strings.
PropertyPermission	PropertyPermission objects represent permission to access system properties.
PropertyResourceBundle	PropertyResourceBundle loads resources from an InputStream.
Random	This class provides methods that generates pseudo-random numbers of different types, such as int, long, double and float using either
ResourceBundle	ResourceBundle is an abstract class which is the superclass of classes which provide locale specific resources.
Scanner	A parser that parses a text string to primitive types with the help of regular expression.
SimpleTimeZone	SimpleTimeZone represents a local time zone and its daylight savings time rules for the gregorian calendar.
Stack	Stack is a Last-In/First-Out(LIFO) data structure which represents a stack of objects.
StringTokenizer	String tokenizer is used to break a string apart into tokens.
Timer	Timers are used to schedule jobs for execution in a background process.
TimerTask	The TimerTask class is represents a task to run at specified time.
TimeZone	TimeZone is an abstract class which represents a local time zone and its daylight savings time rules.
TreeMap	TreeMap is an implementation of SortedMap.
TreeSet	TreeSet is an implementation of SortedSet.
UUID	UUID is an immutable representation of a 128-bit universally unique identifier (UUID).
Vector	Vector is a variable size contiguous indexable array of Objects.
WeakHashMap	WeakHashMap is an implementation of Map with keys which are WeakReferences.

Exception Summary

ConcurrentModificationException	This runtime exception is thrown when a Collection is modified and an existing iterator on the Collection is used to modify the Collection as well.
DuplicateFormatFlagsException	The unchecked exception will be thrown out if there are duplicate flags given out in the format specifier.
EmptyStackException	Runtime exception which is thrown when pop/peek method of stack is executed on a stack which is empty
FormatFlagsConversionMismatchException	The unchecked exception will be thrown out if a conversion and flags are incompatible.
FormatterClosedException	The unchecked exception will be thrown out if the formatter has been closed.
IllegalFormatCodePointException	The unchecked exception will be thrown out if an invalid Unicode code point, which is Character.isValidCodePoint(int), is passed as a parameter to Formatter.
IllegalFormatConversionException	The unchecked exception will be thrown out when the parameter is incompatible with the corresponding format specifier.
IllegalFormatException	Unchecked Exception that is to be thrown out when a format string that contains either an illegal syntax or format specifier is transferred as a parameter.
IllegalFormatFlagsException	The unchecked exception will be thrown out if the combination of the format flags is illegal.
IllegalFormatPrecisionException	The unchecked exception will be thrown out when the precision is a negative other than -1, or the conversion does not support a precision or other cases when the precision is not supported.
IllegalFormatWidthException	The unchecked exception will be thrown out when the width is a negative other than -1, or the conversion does not support a width or other cases when the width is not supported.
InputMismatchException	An InputMismatchException is thrown by a scanner to indicate that the next token does not match the pattern the specified type.
InvalidPropertiesFormatException
MissingFormatArgumentException	The unchecked exception will be thrown out if there no corresponding argument with the specified conversion or an argument index that refers to a missing argument.
MissingFormatWidthException	The unchecked exception will be thrown out if the format width is missing but is required.
MissingResourceException	This runtime exception is thrown by ResourceBundle when a resouce bundle cannot be found or a resource is missing from a resource bundle.
NoSuchElementException	This runtime exception is thrown when trying to retrieve an element past the end of an Enumeration, or the first or last element from an empty Vector.
TooManyListenersException	This exception is thrown when an attempt is made to add more than one listener to an event source which only supports a single listener.
UnknownFormatConversionException	The unchecked exception will be thrown out if the format conversion is unknown.
UnknownFormatFlagsException	The unchecked exception will be thrown out if there is an unknown flag.

Package java.util Description

Provides an extensive set of utility classes. This encompasses things such as basic container data structures (various forms of lists, sets, and maps), classes for dealing with date and time, and their formatting, and