Package ru.progrm_jarvis.javacommons.object.extension

Class LegacyOptionalExtensions

java.lang.Object

ru.progrm_jarvis.javacommons.object.extension.LegacyOptionalExtensions

public final class LegacyOptionalExtensions
extends Object

Extensions to provide new Optional methods on older Java versions.

Method Summary

Modifier and Type	Method	Description
static <T> void	ifPresentOrElse(@NotNull Optional<T> optional, @NotNull Consumer<? super T> action, @NotNull Runnable emptyAction)	Runs the corresponding action depending on whether the optional is present.
static <T> boolean	isEmpty(@NotNull Optional<T> optional)	Checks if the given optional is empty.
static <T> @NotNull Optional<T>	or(@NotNull Optional<T> optional, @NonNull Supplier<@NonNull ? extends Optional<? extends T>> supplier)	Returns the given optional if it is present or an optional provided by the given supplier otherwise.
static <T> T	orElseThrow(@NotNull Optional<T> optional)	Returns the value of the optional if it is present or throws NoSuchElementException otherwise.
static <T> Stream<T>	stream(@NotNull Optional<T> optional)	Returns the stream created from the optional's value if it is present or an empty stream otherwise.

Methods inherited from class java.lang.Object

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

Method Details

isEmpty

public static <T> boolean isEmpty(@NotNull
 @NotNull Optional<T> optional)

Checks if the given optional is empty.

Type Parameters:

T - type of the value

Parameters:

optional - optional on which the operation happens

Returns:

true if the optional is Optional.empty() and false otherwise

API note

this method is available on Optional itself since Java 11

ifPresentOrElse

public static <T> void ifPresentOrElse(@NotNull
 @NotNull Optional<T> optional,
 @NotNull
 @NotNull Consumer<? super T> action,
 @NotNull
 @NotNull Runnable emptyAction)

Runs the corresponding action depending on whether the optional is present.

Type Parameters:

T - type of the value

Parameters:

optional - optional on which the operation happens

action - action to be run on non-empty optional's value

emptyAction - action to be run if the optional is empty

Throws:

NullPointerException - if the optional is present but action is null or if the optional is empty but emptyAction is null

API note

this method is available on Optional itself since Java 9

or

@Contract("_, null -> fail")
@NotNull
public static <T> @NotNull Optional<T> or(@NotNull
 @NotNull Optional<T> optional,
 @NonNull
 @NonNull Supplier<@NonNull ? extends Optional<? extends T>> supplier)

Returns the given optional if it is present or an optional provided by the given supplier otherwise.

Type Parameters:

T - type of the value

Parameters:

optional - optional on which the operation happens

supplier - supplier of the value in case of optional being Optional.empty()

Returns:

given optional if it is present or an optional provided by the given supplier otherwise

Throws:

NullPointerException - if supplier is null or the value provided by it is null

API note

this method is available on Optional itself since Java 9

stream

public static <T> Stream<T> stream(@NotNull
 @NotNull Optional<T> optional)

Returns the stream created from the optional's value if it is present or an empty stream otherwise.

Type Parameters:

T - type of the value

Parameters:

optional - optional on which the operation happens

Returns:

given optional if it is present or an optional provided by the given supplier otherwise

orElseThrow

public static <T> T orElseThrow(@NotNull
 @NotNull Optional<T> optional)

Returns the value of the optional if it is present or throws NoSuchElementException otherwise.

Type Parameters:

T - type of the value

Parameters:

optional - optional on which the operation happens

Returns:

the value of the optional if it is present