java.util - JRE Emulation | JRE Emulation
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).

Package Specification

Related Documentation

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Interfaces

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. 
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). 
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 Observer is the interface to be implemented by objects that receive notification of updates on an Observable object. 
PrimitiveIterator<T, T_CONS> A base type for primitive specializations of Iterator
PrimitiveIterator.OfDouble An Iterator specialized for double values. 
PrimitiveIterator.OfInt An Iterator specialized for int values. 
PrimitiveIterator.OfLong An Iterator specialized for long values. 
Queue<E> A collection designed for holding elements prior to processing. 
RandomAccess RandomAccess is implemented by List implementations that support fast (usually constant time) random access. 
Set<E> A collection that contains no duplicate elements. 
SortedMap<K, V> A Map that further provides a total ordering on its keys. 
SortedSet<E> A Set that further provides a total ordering on its elements. 
Spliterator<T> An object for traversing and partitioning elements of a source. 
Spliterator.OfDouble A Spliterator specialized for double values. 
Spliterator.OfInt A Spliterator specialized for int values. 
Spliterator.OfLong A Spliterator specialized for long values. 
Spliterator.OfPrimitive<T, T_CONS, T_SPLITR extends OfPrimitive<T, T_CONS, T_SPLITR>> A Spliterator specialized for primitive values. 

Classes

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. 
AbstractMap.SimpleEntry<K, V> An Entry maintaining a key and a value. 
AbstractMap.SimpleImmutableEntry<K, V> An Entry maintaining an immutable key and value. 
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). 
Base64 This class consists exclusively of static methods for obtaining encoders and decoders for the Base64 encoding scheme. 
Base64.Decoder This class implements a decoder for decoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045. 
Base64.Encoder This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045. 
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 A currency corresponding to an ISO 4217 currency code such as "EUR" or "USD". 
Date A specific moment 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. 
DoubleSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
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<T extends EventListener> An abstract wrapper class for an EventListener class which associates a set of additional parameters with the listener. 
EventObject EventObjects represent events. 
FormattableFlags FormattableFlags are used as a parameter to formatTo(Formatter, int, int, int) and change the output format in Formattables. 
Formatter Formats arguments according to a format string (like printf in C). 
GregorianCalendar GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar 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 hash table, 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). 
IntSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
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. 
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. 
Locale.Builder A class that helps construct Locale instances. 
LongSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average. 
Objects This class consists of static utility methods for operating on objects. 
Observable Observable is used to notify a group of Observer objects when a change occurs. 
Optional<T> A container object which may or may not contain a non-null value. 
OptionalDouble A container object which may or may not contain a double value. 
OptionalInt A container object which may or may not contain a int value. 
OptionalLong A container object which may or may not contain a long value. 
PriorityQueue<E> An unbounded priority {@linkplain Queue queue} based on a priority heap. 
Properties The Properties class represents a persistent set of properties. 
PropertiesXmlLoader Dynamically loaded implementation for Properties.loadFromXML(). 
PropertyPermission Legacy security code; do not use. 
PropertyResourceBundle PropertyResourceBundle loads resources from an InputStream
Random This class provides methods that return pseudo-random values. 
ResourceBundle ResourceBundle is an abstract class which is the superclass of classes which provide Locale-specific resources. 
ResourceBundle.Control ResourceBundle.Control is a static utility class defines ResourceBundle load access methods, its default access order is as the same as before. 
Scanner A parser that parses a text string of primitive types and strings with the help of regular expressions. 
ServiceLoader<S> A simple service-provider loading facility. 
SimpleTimeZone SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar. 
Spliterators Static classes and methods for operating on or creating instances of Spliterator and its primitive specializations Spliterator.OfInt, Spliterator.OfLong, and Spliterator.OfDouble
Spliterators.AbstractDoubleSpliterator An abstract Spliterator.OfDouble that implements trySplit to permit limited parallelism. 
Spliterators.AbstractIntSpliterator An abstract Spliterator.OfInt that implements trySplit to permit limited parallelism. 
Spliterators.AbstractLongSpliterator An abstract Spliterator.OfLong that implements trySplit to permit limited parallelism. 
Spliterators.AbstractSpliterator<T> An abstract Spliterator that implements trySplit to permit limited parallelism. 
Stack<E> The Stack class represents a last-in-first-out (LIFO) stack of objects. 
StringJoiner StringJoiner is used to construct a sequence of characters separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix. 
StringTokenizer Breaks a string into tokens; new code should probably use split(String)
Timer Timers schedule one-shot or recurring tasks for execution. 
TimerTask The TimerTask class represents a task to run at a specified time. 
TimeZone TimeZone represents a time zone, primarily used for configuring a Calendar or SimpleDateFormat instance. 
TreeMap<K, V> A Red-Black tree based NavigableMap implementation. 
TreeSet<E> A NavigableSet implementation based on a TreeMap
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> Hash table based implementation of the Map interface, with weak keys

Enums

Formatter.BigDecimalLayoutForm The enumeration giving the available styles for formatting very large decimal numbers. 

Exceptions

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 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. 
IllformedLocaleException Thrown by methods in Locale and Locale.Builder to indicate that an argument is not a well-formed BCP 47 tag. 
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. 

Errors

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