compact1
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 Interface Description 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 ofFormatter
.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> ASortedMap
extended with navigation methods returning the closest matches for given search targets.NavigableSet<E> ASortedSet
extended with navigation methods reporting closest matches for given search targets.Observer A class can implement theObserver
interface when it wants to be informed of changes in observable objects.PrimitiveIterator<T,T_CONS> A base type for primitive specializations ofIterator
.PrimitiveIterator.OfDouble An Iterator specialized fordouble
values.PrimitiveIterator.OfInt An Iterator specialized forint
values.PrimitiveIterator.OfLong An Iterator specialized forlong
values.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> AMap
that further provides a total ordering on its keys.SortedSet<E> ASet
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 fordouble
values.Spliterator.OfInt A Spliterator specialized forint
values.Spliterator.OfLong A Spliterator specialized forlong
values.Spliterator.OfPrimitive<T,T_CONS,T_SPLITR extends Spliterator.OfPrimitive<T,T_CONS,T_SPLITR>> A Spliterator specialized for primitive values. -
Class Summary Class Description 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 theList
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 someQueue
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 theDeque
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 TheCalendar
class is an abstract class that provides methods for converting between a specific instant in time and a set ofcalendar fields
such asYEAR
,MONTH
,DAY_OF_MONTH
,HOUR
, and so on, and for manipulating the calendar fields, such as getting the date of the next week.Calendar.Builder Calendar.Builder
is used for creating aCalendar
from various date-time parameters.Collections This class consists exclusively of static methods that operate on or return collections.Currency Represents a currency.Date The classDate
represents a specific instant in time, with millisecond precision.Dictionary<K,V> TheDictionary
class is the abstract parent of any class, such asHashtable
, 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 specializedMap
implementation for use with enum type keys.EnumSet<E extends Enum<E>> A specializedSet
implementation for use with enum types.EventListenerProxy<T extends EventListener> An abstract wrapper class for anEventListener
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 theFormattable.formatTo()
method and modify the output format for Formattables.Formatter An interpreter for printf-style format strings.GregorianCalendar GregorianCalendar
is a concrete subclass ofCalendar
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 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 theList
andDeque
interfaces.ListResourceBundle ListResourceBundle
is an abstract subclass ofResourceBundle
that manages resources for a locale in a convenient and easy to use list.Locale ALocale
object represents a specific geographical, political, or cultural region.Locale.Builder Builder
is used to build instances ofLocale
from values configured by the setters.Locale.LanguageRange This class expresses a Language Range defined in RFC 4647 Matching of Language Tags.LongSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average.Objects This class consists ofstatic
utility methods for operating on objects.Observable This class represents an observable object, or "data" in the model-view paradigm.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 adouble
value.OptionalInt A container object which may or may not contain aint
value.OptionalLong A container object which may or may not contain along
value.PriorityQueue<E> An unbounded priority queue based on a priority heap.Properties TheProperties
class represents a persistent set of properties.PropertyPermission This class is for property permissions.PropertyResourceBundle PropertyResourceBundle
is a concrete subclass ofResourceBundle
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.ResourceBundle.Control ResourceBundle.Control
defines a set of callback methods that are invoked by theResourceBundle.getBundle
factory methods during the bundle loading process.Scanner A simple text scanner which can parse primitive types and strings using regular expressions.ServiceLoader<S> A simple service-provider loading facility.SimpleTimeZone SimpleTimeZone
is a concrete subclass ofTimeZone
that represents a time zone for use with a Gregorian calendar.Spliterators Static classes and methods for operating on or creating instances ofSpliterator
and its primitive specializationsSpliterator.OfInt
,Spliterator.OfLong
, andSpliterator.OfDouble
.Spliterators.AbstractDoubleSpliterator An abstractSpliterator.OfDouble
that implementstrySplit
to permit limited parallelism.Spliterators.AbstractIntSpliterator An abstractSpliterator.OfInt
that implementstrySplit
to permit limited parallelism.Spliterators.AbstractLongSpliterator An abstractSpliterator.OfLong
that implementstrySplit
to permit limited parallelism.Spliterators.AbstractSpliterator<T> An abstractSpliterator
that implementstrySplit
to permit limited parallelism.SplittableRandom A generator of uniform pseudorandom values applicable for use in (among other contexts) isolated parallel computations that may generate subtasks.Stack<E> TheStack
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 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> A Red-Black tree basedNavigableMap
implementation.TreeSet<E> ANavigableSet
implementation based on aTreeMap
.UUID A class that represents an immutable universally unique identifier (UUID).Vector<E> TheVector
class implements a growable array of objects.WeakHashMap<K,V> Hash table based implementation of the Map interface, with weak keys. -
Enum Summary Enum Description Formatter.BigDecimalLayoutForm Enum forBigDecimal
formatting.Locale.Category Enum for locale categories.Locale.FilteringMode This enum provides constants to select a filtering mode for locale matching. -
Exception Summary Exception Description 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 theStack
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 byCharacter.isValidCodePoint(int)
is passed to theFormatter
.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 inLocale
andLocale.Builder
to indicate that an argument is not a well-formed BCP 47 tag.InputMismatchException Thrown by aScanner
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 theProperties
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 various accessor methods to indicate that the element being requested does not exist.TooManyListenersException TheTooManyListenersException
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. -
Error Summary Error Description ServiceConfigurationError Error thrown when something goes wrong while loading a service provider.
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
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2022, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.