Package uk.ac.manchester.spinnaker.utils

Class OptionalUtils

java.lang.Object

uk.ac.manchester.spinnaker.utils.OptionalUtils

public abstract class OptionalUtils
extends Object

Extra utilities for working with Optional in Java 8.

Author:

Donal Fellows

Method Summary

Modifier and Type	Method	Description
static <T> Optional<T>	apply(Optional<T> source, Consumer<T>... actions)	How to apply a sequence of modification transforms to a value in an optional if there is a value there at all.
static <T, U> U	ifElse(Optional<T> source, Function<T,U> ifPresent, Supplier<U> ifAbsent)	How to do one thing if an optional is present, and another if it is absent.
static <T, U> Optional<U>	ifElseFlat(Optional<T> source, Function<T,U> ifPresent, Supplier<U> ifAbsent)	How to do one thing if an optional is present, and another if it is absent.

Methods inherited from class java.lang.Object

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

Method Details

apply

@SafeVarargs
public static <T> Optional<T> apply(Optional<T> source,
 Consumer<T>... actions)

How to apply a sequence of modification transforms to a value in an optional if there is a value there at all.

Type Parameters:

T - The type of value in the optional.

Parameters:

source - Where to get the value from.

actions - The transformations to apply to the value in the optional if it exists; these are expected to modify that object.

Returns:

The original optional.

ifElse

public static <T,
U> U ifElse(Optional<T> source,
 Function<T,U> ifPresent,
 Supplier<U> ifAbsent)

How to do one thing if an optional is present, and another if it is absent.

Type Parameters:

T - The type of value in the optional.

U - The type of the result.

Parameters:

source - Where to get the value from.

ifPresent - What to do if the value is available.

ifAbsent - What to do if the value is not available.

Returns:

The result, depending on which arm was taken.

ifElseFlat

public static <T,
U> Optional<U> ifElseFlat(Optional<T> source,
 Function<T,U> ifPresent,
 Supplier<U> ifAbsent)

How to do one thing if an optional is present, and another if it is absent.

Type Parameters:

T - The type of value in the optional.

U - The type of the result.

Parameters:

source - Where to get the value from.

ifPresent - What to do if the value is available.

ifAbsent - What to do if the value is not available.

Returns:

The result, depending on which arm was taken.