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.constant	Classes and interfaces to represent nominal descriptors for run-time entities such as classes or method handles, and classfile entities such as constant pool entries or invokedynamic call sites.
java.lang.invoke	The java.lang.invoke package provides low-level primitives for interacting with the Java Virtual Machine.
java.lang.module	Classes to support module descriptors and creating configurations of modules by means of resolution and service binding.
java.net	Provides the classes for implementing networking applications.
java.net.http	HTTP Client and WebSocket APIs
java.security.interfaces	Provides interfaces for generating RSA (Rivest, Shamir and Adleman AsymmetricCipher algorithm) keys as defined in the RSA Laboratory Technical Note PKCS#1, and DSA (Digital Signature Algorithm) keys as defined in NIST's FIPS-186.
java.util	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.
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.
javax.naming.ldap.spi
javax.net.ssl	Provides classes for the secure socket package.
jdk.incubator.foreign	Classes to support low-level, safe and efficient memory access.

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.
Optional<ClassDesc>	Class.describeConstable()	Returns a nominal descriptor for this instance, if one can be constructed, or an empty Optional if one cannot be.
Optional<Double>	Double.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
Optional<Enum.EnumDesc<E>>	Enum.describeConstable()	Returns an enum descriptor EnumDesc for this instance, if one can be constructed, or an empty Optional if one cannot be.
Optional<Float>	Float.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
Optional<Integer>	Integer.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
Optional<Long>	Long.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
Optional<String>	String.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
Optional<Module>	ModuleLayer.findModule(String name)	Returns the module with the given name in this layer, or if not in this layer, the parent layers.
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.constant

Methods in java.lang.constant that return Optional

Modifier and Type	Method	Description
Optional<? extends ConstantDesc>	Constable.describeConstable()	Returns an Optional containing the nominal descriptor for this instance, if one can be constructed, or an empty Optional if one cannot be constructed.

Uses of Optional in java.lang.invoke

Methods in java.lang.invoke that return Optional

Modifier and Type	Method	Description
Optional<MethodHandleDesc>	MethodHandle.describeConstable()	Return a nominal descriptor for this instance, if one can be constructed, or an empty Optional if one cannot be.
Optional<MethodTypeDesc>	MethodType.describeConstable()	Return a nominal descriptor for this instance, if one can be constructed, or an empty Optional if one cannot be.
Optional<VarHandle.VarHandleDesc>	VarHandle.describeConstable()	Return a nominal descriptor for this instance, if one can be constructed, or an empty Optional if one cannot be.

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.Requires.rawCompiledVersion()	Returns the string with the possibly-unparseable version of the module if recorded at compile-time.
Optional<String>	ModuleDescriptor.rawVersion()	Returns the string with the possibly-unparseable version of the module
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.net

Methods in java.net that return Optional

Modifier and Type	Method	Description
Optional<SSLSession>	SecureCacheResponse.getSSLSession()	Returns an Optional containing the SSLSession in use on the original connection that retrieved the network resource.

Uses of Optional in java.net.http

Methods in java.net.http that return Optional

Modifier and Type	Method	Description
abstract Optional<Authenticator>	HttpClient.authenticator()	Returns an Optional containing the Authenticator set on this client.
abstract Optional<HttpRequest.BodyPublisher>	HttpRequest.bodyPublisher()	Returns an Optional containing the HttpRequest.BodyPublisher set on this request.
abstract Optional<Duration>	HttpClient.connectTimeout()	Returns an Optional containing the connect timeout duration for this client.
abstract Optional<CookieHandler>	HttpClient.cookieHandler()	Returns an Optional containing this client's CookieHandler.
abstract Optional<Executor>	HttpClient.executor()	Returns an Optional containing this client's Executor.
Optional<String>	HttpHeaders.firstValue(String name)	Returns an Optional containing the first header string value of the given named (and possibly multi-valued) header.
Optional<HttpResponse<T>>	HttpResponse.previousResponse()	Returns an Optional containing the previous intermediate response if one was received.
abstract Optional<ProxySelector>	HttpClient.proxy()	Returns an Optional containing the ProxySelector supplied to this client.
Optional<SSLSession>	HttpResponse.sslSession()	Returns an Optional containing the SSLSession in effect for this response.
abstract Optional<Duration>	HttpRequest.timeout()	Returns an Optional containing this request's timeout duration.
abstract Optional<HttpClient.Version>	HttpRequest.version()	Returns an Optional containing the HTTP protocol version that will be requested for this HttpRequest.

Method parameters in java.net.http with type arguments of type Optional

Modifier and Type	Method	Description
static HttpResponse.BodyHandler<Void>	HttpResponse.BodyHandlers.ofByteArrayConsumer(Consumer<Optional<byte[]>> consumer)	Returns a BodyHandler<Void> that returns a BodySubscriber<Void> obtained from BodySubscribers.ofByteArrayConsumer(Consumer).
static HttpResponse.BodySubscriber<Void>	HttpResponse.BodySubscribers.ofByteArrayConsumer(Consumer<Optional<byte[]>> consumer)	Returns a BodySubscriber which provides the incoming body data to the provided Consumer of Optional<byte[]>.

Uses of Optional in java.security.interfaces

Methods in java.security.interfaces that return Optional

Modifier and Type	Method	Description
Optional<byte[]>	XECPrivateKey.getScalar()	Get the scalar value encoded as an unpruned byte array.

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 service 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.

Uses of Optional in javax.naming.ldap.spi

Methods in javax.naming.ldap.spi that return Optional

Modifier and Type	Method	Description
abstract Optional<LdapDnsProviderResult>	LdapDnsProvider.lookupEndpoints(String url, Map<?,?> env)	Lookup the endpoints and domain name for the given Context provider URL and environment.

Uses of Optional in javax.net.ssl

Methods in javax.net.ssl that return Optional

Modifier and Type	Method	Description
Optional<SSLSession>	HttpsURLConnection.getSSLSession()	Returns an Optional containing the SSLSession in use on this connection.

Uses of Optional in jdk.incubator.foreign

Methods in jdk.incubator.foreign that return Optional

Modifier and Type	Method	Description
Optional<DynamicConstantDesc<GroupLayout>>	GroupLayout.describeConstable()
Optional<? extends DynamicConstantDesc<? extends MemoryLayout>>	MemoryLayout.describeConstable()	Returns an Optional containing the nominal descriptor for this layout, if one can be constructed, or an empty Optional if one cannot be constructed.
Optional<DynamicConstantDesc<SequenceLayout>>	SequenceLayout.describeConstable()
Optional<DynamicConstantDesc<ValueLayout>>	ValueLayout.describeConstable()
Optional<String>	MemoryLayout.name()	Return the name (if any) associated with this layout.