# Uses of Package
java.util

Packages that use java.util
java.applet: Provides the classes necessary to create an applet and the classes an applet uses to communicate with its applet context.
java.awt: Contains all of the classes for creating user interfaces and for painting graphics and images.
java.awt.datatransfer: Provides interfaces and classes for transferring data between and within applications.
java.awt.dnd: Drag and Drop is a direct manipulation gesture found in many Graphical User Interface systems that provides a mechanism to transfer information between two entities logically associated with presentation elements in the GUI.
java.awt.event: Provides interfaces and classes for dealing with different types of events fired by AWT components.
java.awt.font: Provides classes and interface relating to fonts.
java.awt.im: Provides classes and interfaces for the input method framework.
java.awt.im.spi: Provides interfaces that enable the development of input methods that can be used with any Java runtime environment.
java.awt.image: Provides classes for creating and modifying images.
java.awt.image.renderable: Provides classes and interfaces for producing rendering-independent images.
java.beans: Contains classes related to developing beans -- components based on the JavaBeans™ architecture.
java.beans.beancontext: Provides classes and interfaces relating to bean context.
java.io: Provides for system input and output through data streams, serialization and the file system.
java.lang: Provides classes that are fundamental to the design of the Java programming language.
java.lang.invoke: The `java.lang.invoke` package contains dynamic language support provided directly by the Java core class libraries and virtual machine.
java.lang.management: Provides the management interfaces for monitoring and management of the Java virtual machine and other components in the Java runtime.
java.math: Provides classes for performing arbitrary-precision integer arithmetic (`BigInteger`) and arbitrary-precision decimal arithmetic (`BigDecimal`).
java.net: Provides the classes for implementing networking applications.
java.nio.channels: Defines channels, which represent connections to entities that are capable of performing I/O operations, such as files and sockets; defines selectors, for multiplexed, non-blocking I/O operations.
java.nio.channels.spi: Service-provider classes for the ``java.nio.channels`` package.
java.nio.charset: Defines charsets, decoders, and encoders, for translating between bytes and Unicode characters.
java.nio.charset.spi: Service-provider classes for the ``java.nio.charset`` package.
java.nio.file: Defines interfaces and classes for the Java virtual machine to access files, file attributes, and file systems.
java.nio.file.attribute: Interfaces and classes providing access to file and file system attributes.
java.nio.file.spi: Service-provider classes for the ``java.nio.file`` package.
java.rmi.activation: Provides support for RMI Object Activation.
java.security: Provides the classes and interfaces for the security framework.
java.security.acl: The classes and interfaces in this package have been superseded by classes in the java.security package.
java.security.cert: Provides classes and interfaces for parsing and managing certificates, certificate revocation lists (CRLs), and certification paths.
java.sql: Provides the API for accessing and processing data stored in a data source (usually a relational database) using the JavaTM programming language.
java.text: Provides classes and interfaces for handling text, dates, numbers, and messages in a manner independent of natural languages.
java.text.spi: Service provider classes for the classes in the java.text package.
java.time: The main API for dates, times, instants, and durations.
java.time.chrono: Generic API for calendar systems other than the default ISO.
java.time.format: Provides classes to print and parse dates and times.
java.time.temporal: Access to date and time using fields and units, and date time adjusters.
java.time.zone: Support for time-zones and their rules.
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).
java.util.concurrent: Utility classes commonly useful in concurrent programming.
java.util.concurrent.locks: Interfaces and classes providing a framework for locking and waiting for conditions that is distinct from built-in synchronization and monitors.
java.util.function: Functional interfaces provide target types for lambda expressions and method references.
java.util.jar: 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.
java.util.logging: Provides the classes and interfaces of the JavaTM 2 platform's core logging facilities.
java.util.prefs: This package allows applications to store and retrieve user and system preference and configuration data.
java.util.spi: Service provider classes for the classes in the java.util package.
java.util.stream: Classes to support functional-style operations on streams of elements, such as map-reduce transformations on collections.
java.util.zip: Provides classes for reading and writing the standard ZIP and GZIP file formats.
javax.accessibility: Defines a contract between user-interface components and an assistive technology that provides access to those components.
javax.activation
javax.annotation.processing: Facilities for declaring annotation processors and for allowing annotation processors to communicate with an annotation processing tool environment.
javax.imageio: The main package of the Java Image I/O API.
javax.imageio.event: A package of the Java Image I/O API dealing with synchronous notification of events during the reading and writing of images.
javax.imageio.metadata: A package of the Java Image I/O API dealing with reading and writing metadata.
javax.imageio.plugins.bmp: Package containing the public classes used by the built-in BMP plug-in.
javax.imageio.plugins.jpeg: Classes supporting the built-in JPEG plug-in.
javax.imageio.spi: A package of the Java Image I/O API containing the plug-in interfaces for readers, writers, transcoders, and streams, and a runtime registry.
javax.lang.model: Classes and hierarchies of packages used to model the Java programming language.
javax.lang.model.element: Interfaces used to model elements of the Java programming language.
javax.lang.model.type: Interfaces used to model Java programming language types.
javax.lang.model.util: Utilities to assist in the processing of program elements and types.
javax.management: Provides the core classes for the Java Management Extensions.
javax.management.loading: Provides the classes which implement advanced dynamic loading.
javax.management.monitor: Provides the definition of the monitor classes.
javax.management.openmbean: Provides the open data types and Open MBean descriptor classes.
javax.management.relation: Provides the definition of the Relation Service.
javax.management.remote: Interfaces for remote access to JMX MBean servers.
javax.management.remote.rmi: The RMI connector is a connector for the JMX Remote API that uses RMI to transmit client requests to a remote MBean server.
javax.management.timer: Provides the definition of the Timer MBean.
javax.naming: Provides the classes and interfaces for accessing naming services.
javax.naming.directory: Extends the `javax.naming` package to provide functionality for accessing directory services.
javax.naming.event: Provides support for event notification when accessing naming and directory services.
javax.naming.ldap: Provides support for LDAPv3 extended operations and controls.
javax.naming.spi
javax.net.ssl: Provides classes for the secure socket package.
javax.print.attribute: Provides classes and interfaces that describe the types of JavaTM Print Service attributes and how they can be collected into attribute sets.
javax.print.attribute.standard: Package javax.print.attribute.standard contains classes for specific printing attributes.
javax.print.event: Package javax.print.event contains event classes and listener interfaces.
javax.script: The scripting API consists of interfaces and classes that define Java TM Scripting Engines and provides a framework for their use in Java applications.
javax.security.auth: This package provides a framework for authentication and authorization.
javax.security.auth.callback: This package provides the classes necessary for services to interact with applications in order to retrieve information (authentication data including usernames or passwords, for example) or to display information (error and warning messages, for example).
javax.security.auth.kerberos: This package contains utility classes related to the Kerberos network authentication protocol.
javax.security.auth.login: This package provides a pluggable authentication framework.
javax.security.auth.spi: This package provides the interface to be used for implementing pluggable authentication modules.
javax.security.auth.x500: This package contains the classes that should be used to store X500 Principal and X500 Private Credentials in a Subject.
javax.security.sasl: Contains class and interfaces for supporting SASL.
javax.sound.midi: Provides interfaces and classes for I/O, sequencing, and synthesis of MIDI (Musical Instrument Digital Interface) data.
javax.sound.sampled: Provides interfaces and classes for capture, processing, and playback of sampled audio data.
javax.sql: Provides the API for server side data source access and processing from the JavaTM programming language.
javax.sql.rowset: Standard interfaces and base classes for JDBC `RowSet` implementations.
javax.sql.rowset.serial: Provides utility classes to allow serializable mappings between SQL types and data types in the Java programming language.
javax.sql.rowset.spi: The standard classes and interfaces that a third party vendor has to use in its implementation of a synchronization provider.
javax.swing: Provides a set of "lightweight" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.
javax.swing.event: Provides for events fired by Swing components.
javax.swing.plaf.basic: Provides user interface objects built according to the Basic look and feel.
javax.swing.plaf.metal: Provides user interface objects built according to the Java look and feel (once codenamed Metal), which is the default look and feel.
javax.swing.plaf.multi: Provides user interface objects that combine two or more look and feels.
javax.swing.plaf.synth: Synth is a skinnable look and feel in which all painting is delegated.
javax.swing.table: Provides classes and interfaces for dealing with `javax.swing.JTable`.
javax.swing.text: Provides classes and interfaces that deal with editable and noneditable text components.
javax.swing.text.html: Provides the class `HTMLEditorKit` and supporting classes for creating HTML text editors.
javax.swing.text.html.parser: Provides the default HTML parser, along with support classes.
javax.swing.tree: Provides classes and interfaces for dealing with `javax.swing.JTree`.
javax.swing.undo: Allows developers to provide support for undo/redo in applications such as text editors.
javax.tools: Provides interfaces for tools which can be invoked from a program, for example, compilers.
javax.xml.bind: Provides a runtime binding framework for client applications including unmarshalling, marshalling, and validation capabilities.
javax.xml.crypto: Common classes for XML cryptography.
javax.xml.crypto.dom: DOM-specific classes for the `javax.xml.crypto` package.
javax.xml.crypto.dsig: Classes for generating and validating XML digital signatures.
javax.xml.crypto.dsig.keyinfo: Classes for parsing and processing `KeyInfo` elements and structures.
javax.xml.crypto.dsig.spec: Parameter classes for XML digital signatures.
javax.xml.datatype: XML/Java Type Mappings.
javax.xml.namespace: XML Namespace processing.
javax.xml.soap: Provides the API for creating and building SOAP messages.
javax.xml.stream
javax.xml.stream.events
javax.xml.stream.util
javax.xml.transform: This package defines the generic APIs for processing transformation instructions, and performing a transformation from source to result.
javax.xml.ws: This package contains the core JAX-WS APIs.
javax.xml.ws.handler: This package defines APIs for message handlers.
javax.xml.ws.handler.soap: This package defines APIs for SOAP message handlers.
javax.xml.ws.soap: This package defines APIs specific to the SOAP binding.
javax.xml.ws.spi: This package defines SPIs for JAX-WS.
javax.xml.ws.spi.http: Provides HTTP SPI that is used for portable deployment of JAX-WS web services in containers(for e.g.
javax.xml.xpath: This package provides an object-model neutral API for the evaluation of XPath expressions and access to the evaluation environment.
org.omg.CORBA: Provides the mapping of the OMG CORBA APIs to the JavaTM programming language, including the class `ORB`, which is implemented so that a programmer can use it as a fully-functional Object Request Broker (ORB).
org.xml.sax: This package provides the core SAX APIs.
org.xml.sax.helpers: This package contains "helper" classes, including support for bootstrapping SAX-based applications.

Classes in java.util used by java.applet
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Iterator An iterator over a collection.
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by java.awt
Class and Description
Collection The root interface in the collection hierarchy.
EmptyStackException Thrown by methods in the `Stack` class to indicate that the stack is empty.
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
Hashtable This class implements a hash table, which maps keys to values.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Properties The `Properties` class represents a persistent set of properties.
ResourceBundle Resource bundles contain locale-specific objects.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.awt.datatransfer
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.

Classes in java.util used by java.awt.dnd
Class and Description
ArrayList Resizable-array implementation of the `List` interface.
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
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.

Classes in java.util used by java.awt.event
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventListenerProxy An abstract wrapper class for an `EventListener` class which associates a set of additional parameters with the listener.
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by java.awt.font
Class and Description
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.awt.im
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.

Classes in java.util used by java.awt.im.spi
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by java.awt.image
Class and Description
Hashtable This class implements a hash table, which maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by java.awt.image.renderable
Class and Description
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by java.beans
Class and Description
Enumeration 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.
EventListenerProxy An abstract wrapper class for an `EventListener` class which associates a set of additional parameters with the listener.
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by java.beans.beancontext
Class and Description
ArrayList Resizable-array implementation of the `List` interface.
Collection The root interface in the collection hierarchy.
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
HashMap Hash table based implementation of the `Map` interface.
Iterator An iterator over a collection.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
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.

Classes in java.util used by java.io
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by java.lang
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Properties The `Properties` class represents a persistent set of properties.
Spliterator An object for traversing and partitioning elements of a source.

Classes in java.util used by java.lang.invoke
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by java.lang.management
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.math
Class and Description
Random An instance of this class is used to generate a stream of pseudorandom numbers.

Classes in java.util used by java.net
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.

Classes in java.util used by java.nio.channels
Class and Description
Set A collection that contains no duplicate elements.

Classes in java.util used by java.nio.channels.spi
Class and Description
Set A collection that contains no duplicate elements.

Classes in java.util used by java.nio.charset
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Set A collection that contains no duplicate elements.
SortedMap A `Map` that further provides a total ordering on its keys.

Classes in java.util used by java.nio.charset.spi
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by java.nio.file
Class and Description
ConcurrentModificationException This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.nio.file.attribute
Class and Description
List An ordered collection (also known as a sequence).
Set A collection that contains no duplicate elements.

Classes in java.util used by java.nio.file.spi
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.rmi.activation
Class and Description
Properties The `Properties` class represents a persistent set of properties.

Classes in java.util used by java.security
Class and Description
Collection The root interface in the collection hierarchy.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Dictionary The `Dictionary` class is the abstract parent of any class, such as `Hashtable`, which maps keys to values.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Hashtable This class implements a hash table, which maps keys to values.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Properties The `Properties` class represents a persistent set of properties.
Random An instance of this class is used to generate a stream of pseudorandom numbers.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.security.acl
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.

Classes in java.util used by java.security.cert
Class and Description
Collection The root interface in the collection hierarchy.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.sql
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Iterator An iterator over a collection.
Map An object that maps keys to values.
Properties The `Properties` class represents a persistent set of properties.

Classes in java.util used by java.text
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Currency Represents a currency.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.
TimeZone `TimeZone` represents a time zone offset, and also figures out daylight savings.

Classes in java.util used by java.text.spi
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by java.time
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.time.chrono
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.time.format
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.time.temporal
Class and Description
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.

Classes in java.util used by java.time.zone
Class and Description
List An ordered collection (also known as a sequence).
NavigableMap A `SortedMap` extended with navigation methods returning the closest matches for given search targets.
Set A collection that contains no duplicate elements.

Classes in java.util used by java.util
Class and Description
AbstractCollection This class provides a skeletal implementation of the `Collection` interface, to minimize the effort required to implement this interface.
AbstractList 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 This class provides a skeletal implementation of the `Map` interface, to minimize the effort required to implement this interface.
AbstractQueue This class provides skeletal implementations of some `Queue` operations.
AbstractSequentialList 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 This class provides a skeletal implementation of the `Set` interface to minimize the effort required to implement this interface.
ArrayDeque Resizable-array implementation of the `Deque` interface.
ArrayList Resizable-array implementation of the `List` interface.
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 The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `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 a `Calendar` from various date-time parameters.
Collection The root interface in the collection hierarchy.
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Currency Represents a currency.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Deque A linear collection that supports element insertion and removal at both ends.
Dictionary 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.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
EnumMap A specialized `Map` implementation for use with enum type keys.
EnumSet A specialized `Set` implementation for use with enum types.
EventListener A tagging interface that all event listener interfaces must extend.
Formatter An interpreter for printf-style format strings.
Formatter.BigDecimalLayoutForm Enum for `BigDecimal` formatting.
GregorianCalendar `GregorianCalendar` is a concrete subclass of `Calendar` and provides the standard calendar system used by most of the world.
HashMap Hash table based implementation of the `Map` interface.
HashSet This class implements the `Set` interface, backed by a hash table (actually a `HashMap` instance).
Hashtable This class implements a hash table, which maps keys to values.
IllegalFormatException Unchecked exception thrown when a format string contains an illegal syntax or a format specifier that is incompatible with the given arguments.
IntSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average.
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.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
ListIterator 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.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Locale.Builder `Builder` is used to build instances of `Locale` from values configured by the setters.
Locale.Category Enum for locale categories.
Locale.FilteringMode This enum provides constants to select a filtering mode for locale matching.
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.
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
MissingResourceException Signals that a resource is missing.
NavigableMap A `SortedMap` extended with navigation methods returning the closest matches for given search targets.
NavigableSet A `SortedSet` extended with navigation methods reporting closest matches for given search targets.
NoSuchElementException Thrown by various accessor methods to indicate that the element being requested does not exist.
Observable This class represents an observable object, or "data" in the model-view paradigm.
Observer A class can implement the `Observer` interface when it wants to be informed of changes in observable objects.
Optional 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.
PrimitiveIterator 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.
PriorityQueue An unbounded priority queue based on a priority heap.
Properties The `Properties` class represents a persistent set of properties.
Queue A collection designed for holding elements prior to processing.
Random An instance of this class is used to generate a stream of pseudorandom numbers.
RandomAccess Marker interface used by `List` implementations to indicate that they support fast (generally constant time) random access.
ResourceBundle Resource bundles contain locale-specific objects.
ResourceBundle.Control `ResourceBundle.Control` defines a set of callback methods that are invoked by the `ResourceBundle.getBundle` factory methods during the bundle loading process.
Scanner A simple text scanner which can parse primitive types and strings using regular expressions.
ServiceLoader A simple service-provider loading facility.
Set A collection that contains no duplicate elements.
SortedMap A `Map` that further provides a total ordering on its keys.
SortedSet A `Set` that further provides a total ordering on its elements.
Spliterator 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 A Spliterator specialized for primitive values.
SplittableRandom A generator of uniform pseudorandom values applicable for use in (among other contexts) isolated parallel computations that may generate subtasks.
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.
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.
UUID A class that represents an immutable universally unique identifier (UUID).
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by java.util.concurrent
Class and Description
AbstractCollection This class provides a skeletal implementation of the `Collection` interface, to minimize the effort required to implement this interface.
AbstractMap This class provides a skeletal implementation of the `Map` interface, to minimize the effort required to implement this interface.
AbstractQueue This class provides skeletal implementations of some `Queue` operations.
AbstractSet This class provides a skeletal implementation of the `Set` interface to minimize the effort required to implement this interface.
Collection The root interface in the collection hierarchy.
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Deque A linear collection that supports element insertion and removal at both ends.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
ListIterator 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 An object that maps keys to values.
Map.Entry A map entry (key-value pair).
NavigableMap A `SortedMap` extended with navigation methods returning the closest matches for given search targets.
NavigableSet A `SortedSet` extended with navigation methods reporting closest matches for given search targets.
Queue A collection designed for holding elements prior to processing.
Random An instance of this class is used to generate a stream of pseudorandom numbers.
RandomAccess Marker interface used by `List` implementations to indicate that they support fast (generally constant time) random access.
Set A collection that contains no duplicate elements.
SortedMap A `Map` that further provides a total ordering on its keys.
SortedSet A `Set` that further provides a total ordering on its elements.
Spliterator An object for traversing and partitioning elements of a source.

Classes in java.util used by java.util.concurrent.locks
Class and Description
Collection The root interface in the collection hierarchy.
Date The class `Date` represents a specific instant in time, with millisecond precision.

Classes in java.util used by java.util.function
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.

Classes in java.util used by java.util.jar
Class and Description
Collection The root interface in the collection hierarchy.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Set A collection that contains no duplicate elements.
SortedMap A `Map` that further provides a total ordering on its keys.

Classes in java.util used by java.util.logging
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
List An ordered collection (also known as a sequence).
ResourceBundle Resource bundles contain locale-specific objects.

Classes in java.util used by java.util.prefs
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by java.util.spi
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
ResourceBundle.Control `ResourceBundle.Control` defines a set of callback methods that are invoked by the `ResourceBundle.getBundle` factory methods during the bundle loading process.

Classes in java.util used by java.util.stream
Class and Description
Collection The root interface in the collection hierarchy.
Comparator A comparison function, which imposes a total ordering on some collection of objects.
DoubleSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average.
IntSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average.
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
LongSummaryStatistics A state object for collecting statistics such as count, min, max, sum, and average.
Map An object that maps keys to values.
Optional 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.
PrimitiveIterator.OfDouble An Iterator specialized for `double` values.
PrimitiveIterator.OfInt An Iterator specialized for `int` values.
PrimitiveIterator.OfLong An Iterator specialized for `long` values.
Set A collection that contains no duplicate elements.
Spliterator 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.

Classes in java.util used by java.util.zip
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.

Classes in java.util used by javax.accessibility
Class and Description
ListResourceBundle `ListResourceBundle` is an abstract subclass of `ResourceBundle` that manages resources for a locale in a convenient and easy to use list.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
ResourceBundle Resource bundles contain locale-specific objects.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.activation
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.

Classes in java.util used by javax.annotation.processing
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.imageio
Class and Description
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.imageio.event
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.

Classes in java.util used by javax.imageio.metadata
Class and Description
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.imageio.plugins.bmp
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.imageio.plugins.jpeg
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.imageio.spi
Class and Description
Iterator An iterator over a collection.
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.lang.model
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.lang.model.element
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.lang.model.type
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.lang.model.util
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.management
Class and Description
AbstractCollection This class provides a skeletal implementation of the `Collection` interface, to minimize the effort required to implement this interface.
AbstractList 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).
ArrayList Resizable-array implementation of the `List` interface.
Collection The root interface in the collection hierarchy.
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
Hashtable This class implements a hash table, which maps keys to values.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
RandomAccess Marker interface used by `List` implementations to indicate that they support fast (generally constant time) random access.
Set A collection that contains no duplicate elements.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.management.loading
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.management.monitor
Class and Description
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by javax.management.openmbean
Class and Description
Collection The root interface in the collection hierarchy.
Date The class `Date` represents a specific instant in time, with millisecond precision.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.management.relation
Class and Description
AbstractCollection This class provides a skeletal implementation of the `Collection` interface, to minimize the effort required to implement this interface.
AbstractList 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).
ArrayList Resizable-array implementation of the `List` interface.
Collection The root interface in the collection hierarchy.
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
RandomAccess Marker interface used by `List` implementations to indicate that they support fast (generally constant time) random access.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.management.remote
Class and Description
EventObject The root class from which all event state objects shall be derived.
Map An object that maps keys to values.

Classes in java.util used by javax.management.remote.rmi
Class and Description
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.management.timer
Class and Description
Date The class `Date` represents a specific instant in time, with millisecond precision.
EventObject The root class from which all event state objects shall be derived.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.naming
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Hashtable This class implements a hash table, which maps keys to values.
Properties The `Properties` class represents a persistent set of properties.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.naming.directory
Class and Description
Hashtable This class implements a hash table, which maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.naming.event
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by javax.naming.ldap
Class and Description
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
Hashtable This class implements a hash table, which maps keys to values.
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.naming.spi
Class and Description
Hashtable This class implements a hash table, which maps keys to values.

Classes in java.util used by javax.net.ssl
Class and Description
Collection The root interface in the collection hierarchy.
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.print.attribute
Class and Description
Date The class `Date` represents a specific instant in time, with millisecond precision.
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.print.attribute.standard
Class and Description
AbstractCollection This class provides a skeletal implementation of the `Collection` interface, to minimize the effort required to implement this interface.
AbstractMap This class provides a skeletal implementation of the `Map` interface, to minimize the effort required to implement this interface.
AbstractSet This class provides a skeletal implementation of the `Set` interface to minimize the effort required to implement this interface.
Collection The root interface in the collection hierarchy.
Date The class `Date` represents a specific instant in time, with millisecond precision.
HashMap Hash table based implementation of the `Map` interface.
HashSet This class implements the `Set` interface, backed by a hash table (actually a `HashMap` instance).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.print.event
Class and Description
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by javax.script
Class and Description
Collection The root interface in the collection hierarchy.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Map.Entry A map entry (key-value pair).
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.security.auth
Class and Description
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.security.auth.callback
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.security.auth.kerberos
Class and Description
Date The class `Date` represents a specific instant in time, with millisecond precision.

Classes in java.util used by javax.security.auth.login
Class and Description
Map An object that maps keys to values.

Classes in java.util used by javax.security.auth.spi
Class and Description
Map An object that maps keys to values.

Classes in java.util used by javax.security.auth.x500
Class and Description
Map An object that maps keys to values.

Classes in java.util used by javax.security.sasl
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Map An object that maps keys to values.

Classes in java.util used by javax.sound.midi
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.sound.sampled
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
Map An object that maps keys to values.

Classes in java.util used by javax.sql
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.
Map An object that maps keys to values.

Classes in java.util used by javax.sql.rowset
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Collection The root interface in the collection hierarchy.
Map An object that maps keys to values.

Classes in java.util used by javax.sql.rowset.serial
Class and Description
Map An object that maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.sql.rowset.spi
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.

Classes in java.util used by javax.swing
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Date The class `Date` represents a specific instant in time, with millisecond precision.
Dictionary The `Dictionary` class is the abstract parent of any class, such as `Hashtable`, which maps keys to values.
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
Hashtable This class implements a hash table, which maps keys to values.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.event
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
EventObject The root class from which all event state objects shall be derived.

Classes in java.util used by javax.swing.plaf.basic
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
Hashtable This class implements a hash table, which maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.plaf.metal
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.

Classes in java.util used by javax.swing.plaf.multi
Class and Description
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.plaf.synth
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.

Classes in java.util used by javax.swing.table
Class and Description
Comparator A comparison function, which imposes a total ordering on some collection of objects.
Enumeration 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.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.text
Class and Description
Dictionary The `Dictionary` class is the abstract parent of any class, such as `Hashtable`, which maps keys to values.
Enumeration 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.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.text.html
Class and Description
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.text.html.parser
Class and Description
BitSet This class implements a vector of bits that grows as needed.
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Hashtable This class implements a hash table, which maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.tree
Class and Description
Enumeration 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.
EventObject The root class from which all event state objects shall be derived.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.swing.undo
Class and Description
EventListener A tagging interface that all event listener interfaces must extend.
Hashtable This class implements a hash table, which maps keys to values.
Vector The `Vector` class implements a growable array of objects.

Classes in java.util used by javax.tools
Class and Description
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Locale A `Locale` object represents a specific geographical, political, or cultural region.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.xml.bind
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Map An object that maps keys to values.

Classes in java.util used by javax.xml.crypto
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by javax.xml.crypto.dom
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by javax.xml.crypto.dsig
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.xml.crypto.dsig.keyinfo
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.xml.crypto.dsig.spec
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.

Classes in java.util used by javax.xml.datatype
Class and Description
Calendar The `Calendar` class is an abstract class that provides methods for converting between a specific instant in time and a set of `calendar fields` such as `YEAR`, `MONTH`, `DAY_OF_MONTH`, `HOUR`, and so on, and for manipulating the calendar fields, such as getting the date of the next week.
Date The class `Date` represents a specific instant in time, with millisecond precision.
GregorianCalendar `GregorianCalendar` is a concrete subclass of `Calendar` and provides the standard calendar system used by most of the world.
Locale A `Locale` object represents a specific geographical, political, or cultural region.
TimeZone `TimeZone` represents a time zone offset, and also figures out daylight savings.

Classes in java.util used by javax.xml.namespace
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by javax.xml.soap
Class and Description
Iterator An iterator over a collection.
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by javax.xml.stream
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by javax.xml.stream.events
Class and Description
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.xml.stream.util
Class and Description
Iterator An iterator over a collection.

Classes in java.util used by javax.xml.transform
Class and Description
Properties The `Properties` class represents a persistent set of properties.

Classes in java.util used by javax.xml.ws
Class and Description
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.xml.ws.handler
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.

Classes in java.util used by javax.xml.ws.handler.soap
Class and Description
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.xml.ws.soap
Class and Description
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.xml.ws.spi
Class and Description
Iterator An iterator over a collection.
List An ordered collection (also known as a sequence).

Classes in java.util used by javax.xml.ws.spi.http
Class and Description
List An ordered collection (also known as a sequence).
Map An object that maps keys to values.
Set A collection that contains no duplicate elements.

Classes in java.util used by javax.xml.xpath
Class and Description
List An ordered collection (also known as a sequence).

Classes in java.util used by org.omg.CORBA
Class and Description
Properties The `Properties` class represents a persistent set of properties.

Classes in java.util used by org.xml.sax
Class and Description
Locale A `Locale` object represents a specific geographical, political, or cultural region.

Classes in java.util used by org.xml.sax.helpers
Class and Description
Enumeration An object that implements the Enumeration interface generates a series of elements, one at a time.
Locale A `Locale` object represents a specific geographical, political, or cultural region.