Uses of Class
java.util.Optional

Packages that use Optional

Package	Description
java.lang	Provides classes that are fundamental to the design of the Java programming language.
java.lang.module	Classes to support module descriptors and creating configurations of modules by means of resolution and service binding.
java.lang.reflect	Provides classes and interfaces for obtaining reflective information about modules, classes and objects.
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.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.

Uses of Optional in java.lang

Methods in java.lang that return Optional

Modifier and Type	Method	Description
Optional<String[]>	ProcessHandle.Info.arguments()	Returns an array of Strings of the arguments of the process.
Optional<Integer>	Runtime.Version.build()	Returns the build number.
Optional<String>	ProcessHandle.Info.command()	Returns the executable pathname of the process.
Optional<String>	ProcessHandle.Info.commandLine()	Returns the command line of the process.
static Optional<ProcessHandle>	ProcessHandle.of(long pid)	Returns an Optional<ProcessHandle> for an existing native process.
Optional<String>	Runtime.Version.optional()	Returns optional additional identifying build information.
Optional<ProcessHandle>	ProcessHandle.parent()	Returns an Optional<ProcessHandle> for the parent process.
Optional<String>	Runtime.Version.pre()	Returns the optional pre-release information.
Optional<Instant>	ProcessHandle.Info.startInstant()	Returns the start time of the process.
Optional<Duration>	ProcessHandle.Info.totalCpuDuration()	Returns the total cputime accumulated of the process.
Optional<String>	ProcessHandle.Info.user()	Return the user of the process.

Uses of Optional in java.lang.module

Methods in java.lang.module that return Optional

Modifier and Type	Method	Description
Optional<ModuleDescriptor.Version>	ModuleDescriptor.Requires.compiledVersion()	Returns the version of the module if recorded at compile-time.
Optional<ModuleReference>	ModuleFinder.find(String name)	Finds a reference to a module of a given name.
Optional<URI>	ModuleReader.find(String name)	Finds a resource, returning a URI to the resource in the module.
Optional<ResolvedModule>	Configuration.findModule(String name)	Finds a resolved module in this configuration, or if not in this configuration, the parent configurations.
Optional<URI>	ModuleReference.location()	Returns the location of this module's content, if known.
Optional<String>	ModuleDescriptor.mainClass()	Returns the module main class.
default Optional<InputStream>	ModuleReader.open(String name)	Opens a resource, returning an input stream to read the resource in the module.
Optional<String>	ModuleDescriptor.osArch()	Returns the operating system architecture if the module is operating system architecture specific.
Optional<String>	ModuleDescriptor.osName()	Returns the operating system name if the module is operating system specific.
Optional<String>	ModuleDescriptor.osVersion()	Returns the operating system version if the module is operating system version specific.
default Optional<ByteBuffer>	ModuleReader.read(String name)	Reads a resource, returning a byte buffer with the contents of the resource.
Optional<ModuleDescriptor.Version>	ModuleDescriptor.version()	Returns the module version.

Uses of Optional in java.lang.reflect

Methods in java.lang.reflect that return Optional

Modifier and Type	Method	Description
Optional<Module>	Layer.findModule(String name)	Returns the module with the given name in this layer, or if not in this layer, the parent layers.

Uses of Optional in java.util

Methods in java.util that return Optional

Modifier and Type	Method	Description
static <T> Optional<T>	Optional.empty()	Returns an empty Optional instance.
Optional<T>	Optional.filter(Predicate<? super T> predicate)	If a value is present, and the value matches the given predicate, returns an Optional describing the value, otherwise returns an empty Optional.
Optional<S>	ServiceLoader.findFirst()	Load the first available provider of this loader's service.
<U> Optional<U>	Optional.flatMap(Function<? super T,? extends Optional<? extends U>> mapper)	If a value is present, returns the result of applying the given Optional-bearing mapping function to the value, otherwise returns an empty Optional.
<U> Optional<U>	Optional.map(Function<? super T,? extends U> mapper)	If a value is present, returns an Optional describing (as if by ofNullable(T)) the result of applying the given mapping function to the value, otherwise returns an empty Optional.
static <T> Optional<T>	Optional.of(T value)	Returns an Optional describing the given non-null value.
static <T> Optional<T>	Optional.ofNullable(T value)	Returns an Optional describing the given value, if non-null, otherwise returns an empty Optional.
Optional<T>	Optional.or(Supplier<? extends Optional<? extends T>> supplier)	If a value is present, returns an Optional describing the value, otherwise returns an Optional produced by the supplying function.

Method parameters in java.util with type arguments of type Optional

Modifier and Type	Method	Description
<U> Optional<U>	Optional.flatMap(Function<? super T,? extends Optional<? extends U>> mapper)	If a value is present, returns the result of applying the given Optional-bearing mapping function to the value, otherwise returns an empty Optional.
Optional<T>	Optional.or(Supplier<? extends Optional<? extends T>> supplier)	If a value is present, returns an Optional describing the value, otherwise returns an Optional produced by the supplying function.

Uses of Optional in java.util.spi

Methods in java.util.spi that return Optional

Modifier and Type	Method	Description
static Optional<ToolProvider>	ToolProvider.findFirst(String name)	Returns the first instance of a ToolProvider with the given name, as loaded by ServiceLoader using the system class loader.

Uses of Optional in java.util.stream

Methods in java.util.stream that return Optional

Modifier and Type	Method	Description
Optional<T>	Stream.findAny()	Returns an Optional describing some element of the stream, or an empty Optional if the stream is empty.
Optional<T>	Stream.findFirst()	Returns an Optional describing the first element of this stream, or an empty Optional if the stream is empty.
Optional<T>	Stream.max(Comparator<? super T> comparator)	Returns the maximum element of this stream according to the provided Comparator.
Optional<T>	Stream.min(Comparator<? super T> comparator)	Returns the minimum element of this stream according to the provided Comparator.
Optional<T>	Stream.reduce(BinaryOperator<T> accumulator)	Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an Optional describing the reduced value, if any.

Methods in java.util.stream that return types with arguments of type Optional

Modifier and Type	Method	Description
static <T> Collector<T,?,Optional<T>>	Collectors.maxBy(Comparator<? super T> comparator)	Returns a Collector that produces the maximal element according to a given Comparator, described as an Optional<T>.
static <T> Collector<T,?,Optional<T>>	Collectors.minBy(Comparator<? super T> comparator)	Returns a Collector that produces the minimal element according to a given Comparator, described as an Optional<T>.
static <T> Collector<T,?,Optional<T>>	Collectors.reducing(BinaryOperator<T> op)	Returns a Collector which performs a reduction of its input elements under a specified BinaryOperator.