Package com.globalmentor.util

Class Optionals

java.lang.Object

com.globalmentor.util.Optionals

public class Optionals
extends java.lang.Object

Utilities to use with Optional.

Author:

Garret Wilson

Constructor Summary

Constructors

Constructor	Description
Optionals()

Method Summary

Modifier and Type	Method	Description
static <T> void	ifPresentOrElse(java.util.Optional<T> optional, java.util.function.Consumer<? super T> action, java.lang.Runnable emptyAction)	Performs an action with the value if a value is present, otherwise performs another action.
static boolean	isPresentAndEquals(java.util.Optional<?> optional, java.lang.Object object)	Determines whether an optional value is present and is equal to some other nullable object.
static <T> java.util.Optional<T>	or(java.util.Optional<T> optional, java.util.function.Supplier<java.util.Optional<T>> supplier)	Returns another another optional from a supplier if the given optional is not present.
static <T> java.util.stream.Stream<T>	stream(java.util.Optional<T> optional)	Converts an optional to a stream.
static java.util.OptionalDouble	toOptionalDouble(java.util.Optional<java.lang.Double> optional)	Converts an optional wrapper Double instance to a primitive containing OptionalDouble instance.
static java.util.OptionalInt	toOptionalInt(java.util.Optional<java.lang.Integer> optional)	Converts an optional wrapper Integer instance to a primitive containing OptionalInt instance.
static java.util.OptionalLong	toOptionalLong(java.util.Optional<java.lang.Long> optional)	Converts an optional wrapper Long instance to a primitive containing OptionalLong instance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Optionals

public Optionals()

Method Detail

or

public static <T> java.util.Optional<T> or(@Nonnull
                                           java.util.Optional<T> optional,
                                           @Nonnull
                                           java.util.function.Supplier<java.util.Optional<T>> supplier)

Returns another another optional from a supplier if the given optional is not present.

API Note:

This method duplicates functionality in Java 9.

Type Parameters:

T - The type of value contained in the optional.

Parameters:

optional - The optional to check

supplier - The supplier of an alternative optional if the value of the given optional is not present.

Returns:

The given optional or, if the value is not present, an optional one returned by the given supplier.

Throws:

java.lang.NullPointerException - if the supplier is null or returns null.

See Also:

JDK-8080418, Optional.or()

ifPresentOrElse

public static <T> void ifPresentOrElse(@Nonnull
                                       java.util.Optional<T> optional,
                                       @Nonnull
                                       java.util.function.Consumer<? super T> action,
                                       @Nonnull
                                       java.lang.Runnable emptyAction)

Performs an action with the value if a value is present, otherwise performs another action.

API Note:

This method duplicates functionality in Java 9.

Type Parameters:

T - The type of value contained in the optional.

Parameters:

optional - The optional to check

action - The action to perform if the value is present.

emptyAction - The action to perform if no value is present.

Throws:

java.lang.NullPointerException - if a value is present and the given action is null, or if no value is present and the given empty action is null.

See Also:

Optional.ifPresentOrElse()

isPresentAndEquals

public static boolean isPresentAndEquals(@Nonnull
                                         java.util.Optional<?> optional,
                                         @Nullable
                                         java.lang.Object object)

Determines whether an optional value is present and is equal to some other nullable object.

API Note:

Note that the given object with which to compare the optional object can be null, as per the parameter of Object.equals(Object).

Implementation Specification:

This method is equivalent to calling Optional.isPresent() and if the result is true, calling Object.equals(Object) on the contained object.

Parameters:

optional - The optional to check

object - The object to compare for equality with the optional value.

Returns:

true if the given optional value is present and is equal to the given object.

Throws:

java.lang.NullPointerException - if the given optional is null.

See Also:

Optional.isPresent(), Optional.get(), Optional.equals(Object)

stream

public static <T> java.util.stream.Stream<T> stream(@Nonnull
                                                    java.util.Optional<T> optional)

Converts an optional to a stream.

API Note:

This method duplicates functionality in Java 9.

Type Parameters:

T - The type of value contained in the optional.

Parameters:

optional - The optional to check

Returns:

A stream, either containing the optional value, or empty if the optional is empty.

See Also:

Optional.stream()

toOptionalDouble

public static java.util.OptionalDouble toOptionalDouble(@Nonnull
                                                        java.util.Optional<java.lang.Double> optional)

Converts an optional wrapper Double instance to a primitive containing OptionalDouble instance.

Parameters:

optional - The Optional instance to convert.

Returns:

The equivalent primitive optional wrapper.

toOptionalInt

public static java.util.OptionalInt toOptionalInt(@Nonnull
                                                  java.util.Optional<java.lang.Integer> optional)

Converts an optional wrapper Integer instance to a primitive containing OptionalInt instance.

Parameters:

optional - The Optional instance to convert.

Returns:

The equivalent primitive optional wrapper.

toOptionalLong

public static java.util.OptionalLong toOptionalLong(@Nonnull
                                                    java.util.Optional<java.lang.Long> optional)

Converts an optional wrapper Long instance to a primitive containing OptionalLong instance.

Parameters:

optional - The Optional instance to convert.

Returns:

The equivalent primitive optional wrapper.