Contains the collections framework, some internationalization support classes, a service loader, properties, random number generation, string parsing and scanning classes, base64 encoding and decoding, a bit array, and several miscellaneous utility classes. This package also contains legacy collection classes and legacy date and time classes.
For an overview, API outline, and design rationale, please see:
For a tutorial and programming guide with examples of use of the collections framework, please see:
ModulePackageDescriptionUtility classes commonly useful in concurrent programming.Functional interfaces provide target types for lambda expressions and method references.Provides classes for reading and writing the JAR (Java ARchive) file format, which is based on the standard ZIP file format with an optional manifest file.Provides the classes and interfaces of the Java 2 platform's core logging facilities.This package allows applications to store and retrieve user and system preference and configuration data.This package contains classes and interfaces that support a generic API for random number generation.Classes for matching character sequences against patterns specified by regular expressions.Service provider classes for the classes in the java.util package.Classes to support functional-style operations on streams of elements, such as map-reduce transformations on collections.Provides classes for reading and writing the standard ZIP and GZIP file formats.
InterfaceDescriptionCollection<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.A tagging interface that all event listener interfaces must extend.The
Formattableinterface 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
SortedMapextended with navigation methods returning the closest matches for given search targets.NavigableSet<E>A
SortedSetextended with navigation methods reporting closest matches for given search targets.Deprecated.This interface has been deprecated.PrimitiveIterator<T,T_CONS>A base type for primitive specializations of
Iterator.An Iterator specialized for
doublevalues.An Iterator specialized for
intvalues.An Iterator specialized for
longvalues.Queue<E>A collection designed for holding elements prior to processing.Marker interface used by
Listimplementations to indicate that they support fast (generally constant time) random access.Represents a service provider located by
ServiceLoader.Set<E>A collection that contains no duplicate elements.SortedMap<K,V>A
Mapthat further provides a total ordering on its keys.SortedSet<E>A
Setthat further provides a total ordering on its elements.Spliterator<T>An object for traversing and partitioning elements of a source.A Spliterator specialized for
doublevalues.A Spliterator specialized for
intvalues.A Spliterator specialized for
longvalues.A Spliterator specialized for primitive values.
ClassDescriptionThis class provides a skeletal implementation of the
Collectioninterface, to minimize the effort required to implement this interface.AbstractList<E>This class provides a skeletal implementation of the
Listinterface 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
Mapinterface, to minimize the effort required to implement this interface.AbstractMap.SimpleEntry<K,V>An Entry maintaining a key and a value.An Entry maintaining an immutable key and value.This class provides skeletal implementations of some
Queueoperations.This class provides a skeletal implementation of the
Listinterface 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
Setinterface to minimize the effort required to implement this interface.ArrayDeque<E>Resizable-array implementation of the
Dequeinterface.ArrayList<E>Resizable-array implementation of the
Listinterface.This class contains various methods for manipulating arrays (such as sorting and searching).This class consists exclusively of static methods for obtaining encoders and decoders for the Base64 encoding scheme.This class implements a decoder for decoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.This class implements an encoder for encoding byte data using the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.This class implements a vector of bits that grows as needed.The
Calendarclass is an abstract class that provides methods for converting between a specific instant in time and a set of
calendar fieldssuch as
HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Calendar.Builderis used for creating a
Calendarfrom various date-time parameters.This class consists exclusively of static methods that operate on or return collections.Represents a currency.The class
Daterepresents a specific instant in time, with millisecond precision.Dictionary<K,V>The
Dictionaryclass is the abstract parent of any class, such as
Hashtable, which maps keys to values.A state object for collecting statistics such as count, min, max, sum, and average.A specialized
Mapimplementation for use with enum type keys.A specialized
Setimplementation for use with enum types.An abstract wrapper class for an
EventListenerclass which associates a set of additional parameters with the listener.The root class from which all event state objects shall be derived.An interpreter for printf-style format strings.
GregorianCalendaris a concrete subclass of
Calendarand provides the standard calendar system used by most of the world.HashMap<K,V>Hash table based implementation of the
Mapinterface.HashSet<E>This class implements the
Setinterface, backed by a hash table (actually a
HashMapinstance).Hashtable<K,V>This class implements a hash table, which maps keys to values.
HexFormatconverts between bytes and chars and hex-encoded strings which may include additional formatting markup such as prefixes, suffixes, and delimiters.IdentityHashMap<K,V>This class implements the
Mapinterface with a hash table, using reference-equality in place of object-equality when comparing keys (and values).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
Mapinterface, with predictable iteration order.Hash table and linked list implementation of the
Setinterface, with predictable iteration order.LinkedList<E>Doubly-linked list implementation of the
ListResourceBundleis an abstract subclass of
ResourceBundlethat manages resources for a locale in a convenient and easy to use list.A
Localeobject represents a specific geographical, political, or cultural region.
Builderis used to build instances of
Localefrom values configured by the setters.This class expresses a Language Range defined in RFC 4647 Matching of Language Tags.A state object for collecting statistics such as count, min, max, sum, and average.This class consists of
staticutility methods for operating on objects, or checking certain conditions before operation.Deprecated.This class and the
Observerinterface have been deprecated.Optional<T>A container object which may or may not contain a non-
nullvalue.A container object which may or may not contain a
doublevalue.A container object which may or may not contain an
intvalue.A container object which may or may not contain a
longvalue.An unbounded priority queue based on a priority heap.The
Propertiesclass represents a persistent set of properties.This class is for property permissions.
PropertyResourceBundleis a concrete subclass of
ResourceBundlethat manages resources for a locale using a set of static strings from a property file.An instance of this class is used to generate a stream of pseudorandom numbers; its period is only 248.Resource bundles contain locale-specific objects.
ResourceBundle.Controldefines a set of callback methods that are invoked by the
ResourceBundle.getBundlefactory methods during the bundle loading process.A simple text scanner which can parse primitive types and strings using regular expressions.A facility to load implementations of a service.
SimpleTimeZoneis a concrete subclass of
TimeZonethat represents a time zone for use with a Gregorian calendar.An abstract
trySplitto permit limited parallelism.An abstract
trySplitto permit limited parallelism.An abstract
trySplitto permit limited parallelism.An abstract
trySplitto permit limited parallelism.A generator of uniform pseudorandom values (with period 264) applicable for use in (among other contexts) isolated parallel computations that may generate subtasks.Stack<E>The
Stackclass represents a last-in-first-out (LIFO) stack of objects.
StringJoineris used to construct a sequence of characters separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix.The string tokenizer class allows an application to break a string into tokens.A facility for threads to schedule tasks for future execution in a background thread.A task that can be scheduled for one-time or repeated execution by a
TimeZonerepresents a time zone offset, and also figures out daylight savings.TreeMap<K,V>A Red-Black tree based
NavigableMapimplementation.TreeSet<E>A class that represents an immutable universally unique identifier (UUID).Vector<E>The
Vectorclass implements a growable array of objects.WeakHashMap<K,V>Hash table based implementation of the
Mapinterface, with weak keys.
ExceptionDescriptionThis exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.Unchecked exception thrown when duplicate flags are provided in the format specifier.Thrown by methods in the
Stackclass to indicate that the stack is empty.Unchecked exception thrown when a conversion and flag are incompatible.Unchecked exception thrown when the formatter has been closed.Unchecked exception thrown when the argument corresponding to the format specifier is of an incompatible type.Unchecked exception thrown when a format string contains an illegal syntax or a format specifier that is incompatible with the given arguments.Unchecked exception thrown when an illegal combination flags is given.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.Unchecked exception thrown when the format width is a negative value other than
-1or is otherwise unsupported.Thrown by a
Scannerto 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.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
Propertiesspecification.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.Unchecked exception thrown when the format width is required.Signals that a resource is missing.Thrown by various accessor methods to indicate that the element being requested does not exist.The
TooManyListenersExceptionException is used as part of the Java Event model to annotate and implement a unicast special case of a multicast Event Source.Unchecked exception thrown when an unknown conversion is given.Unchecked exception thrown when an unknown flag is given.
ErrorDescriptionError thrown when something goes wrong while locating, loading, or instantiating a service provider.