Package io.helidon.common

Class OptionalHelper<T>

java.lang.Object

io.helidon.common.OptionalHelper<T>

Type Parameters:

T - the type of the underlying optional value

public class OptionalHelper<T>
extends Object

A wrapper on top of Optional to replicate some of the new Java9 methods.

Method Summary

Modifier and Type	Method	Description
Optional<T>	asOptional()	Get the underlying Optional instance.
static <T> OptionalHelper<T>	from(Optional<T> optional)	Static factory method to create a new OptionalHelper instance.
void	ifPresentOrElse(Consumer<T> action, Runnable emptyAction)	If a value is present, performs the given action with the value, otherwise performs the given empty-based action.
OptionalHelper<T>	or(Supplier<? extends Optional<T>> supplier)	If the underlying Optional does not have a value, set it to the Optional produced by the supplying function.
Stream<T>	stream()	If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Methods inherited from class java.lang.Object

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

Method Detail

from

public static <T> OptionalHelper<T> from(Optional<T> optional)

Static factory method to create a new OptionalHelper instance.

Type Parameters:

T - the type of the underly optional value

Parameters:

optional - the optional to wrap

Returns:

the created OptionalHelper instance

asOptional

public Optional<T> asOptional()

Get the underlying Optional instance.

Returns:

the wrapped Optional

or

public OptionalHelper<T> or(Supplier<? extends Optional<T>> supplier)

If the underlying Optional does not have a value, set it to the Optional produced by the supplying function.

Parameters:

supplier - the supplying function that produces an Optional

Returns:

returns this instance of OptionalHelper with the same the underlying Optional if a value is present, otherwise with the Optional produced by the supplying function.

Throws:

NullPointerException - if the supplying function is null or produces a null result

ifPresentOrElse

public void ifPresentOrElse(Consumer<T> action,
                            Runnable emptyAction)

If a value is present, performs the given action with the value, otherwise performs the given empty-based action.

Parameters:

action - the action to be performed, if a value is present

emptyAction - the empty-based action to be performed, if no value is present

Throws:

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

stream

public Stream<T> stream()

If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Returns:

the optional value as a Stream