Package io.vertx.rxjava3

## Class MaybeHelper

- java.lang.Object
- - io.vertx.rxjava3.MaybeHelper

-     public class MaybeHelper
      extends Object

  Author:
    Julien Viet

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `MaybeHelper()` |

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `static <T> MaybeObserver<T>` | `nullObserver()` |
    `static <T> Future<T>` | `toFuture​(Maybe<T> maybe)` | Adapts an RxJava2 `Maybe<T>` to a Vert.x `Future`.
    `static <T,​U> Future<U>` | `toFuture​(Maybe<T> maybe, Function<T,​U> adapter)` | Like `toFuture(Maybe)` but with an `adapter` of the result.
    `static <T> Maybe<T>` | `toMaybe​(Consumer<Handler<AsyncResult<T>>> handler)` | Returns a `Maybe` that, when subscribed, uses the provided `handler` to adapt a callback-based asynchronous method.
    `static <T> MaybeObserver<T>` | `toObserver​(Handler<AsyncResult<T>> handler)` | Adapts an Vert.x `Handler<AsyncResult<T>>` to an RxJava2 `MaybeObserver`.
    `static <T> MaybeTransformer<Buffer,​T>` | `unmarshaller​(TypeReference<T> mappedTypeRef)` |
    `static <T> MaybeTransformer<Buffer,​T>` | `unmarshaller​(TypeReference<T> mappedTypeRef, ObjectCodec mapper)` |
    `static <T> MaybeTransformer<Buffer,​T>` | `unmarshaller​(Class<T> mappedType)` |
    `static <T> MaybeTransformer<Buffer,​T>` | `unmarshaller​(Class<T> mappedType, ObjectCodec mapper)` |

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### MaybeHelper

          public MaybeHelper()

  - ### Method Detail

    - #### nullObserver

          public static <T> MaybeObserver<T> nullObserver()

      Returns:
        a `MaybeObserver` that does nothing

    - #### toMaybe

          public static <T> Maybe<T> toMaybe​(Consumer<Handler<AsyncResult<T>>> handler)

      Returns a `Maybe` that, when subscribed, uses the provided `handler` to adapt a callback-based asynchronous method.

      For example:

           io.vertx.core.Vertx vertx = Vertx.vertx();
           Maybe<String> blockingMethodResult = MaybeHelper.toMaybe(handler -> vertx.<String>executeBlocking(fut -> fut.complete(invokeBlocking()), handler));

      This is useful when using RxJava without the Vert.x Rxified API or your own asynchronous methods.

      Parameters:
        `handler` - the code executed when the returned `Maybe` is subscribed

    - #### toObserver

          public static <T> MaybeObserver<T> toObserver​(Handler<AsyncResult<T>> handler)

      Adapts an Vert.x `Handler<AsyncResult<T>>` to an RxJava2 `MaybeObserver`.

      The returned observer can be subscribed to an `Maybe.subscribe(MaybeObserver)`.

      Parameters:
        `handler` - the handler to adapt
      Returns:
        the observer

    - #### toFuture

          public static <T> Future<T> toFuture​(Maybe<T> maybe)

      Adapts an RxJava2 `Maybe<T>` to a Vert.x `Future`.

      The maybe will be immediately subscribed and the returned future will be updated with the result of the single.

      Parameters:
        `maybe` - the single to adapt
      Returns:
        the future

    - #### toFuture

          public static <T,​U> Future<U> toFuture​(Maybe<T> maybe,
                                                       Function<T,​U> adapter)

      Like `toFuture(Maybe)` but with an `adapter` of the result.

    - #### unmarshaller

          public static <T> MaybeTransformer<Buffer,​T> unmarshaller​(Class<T> mappedType)

    - #### unmarshaller

          public static <T> MaybeTransformer<Buffer,​T> unmarshaller​(TypeReference<T> mappedTypeRef)

    - #### unmarshaller

          public static <T> MaybeTransformer<Buffer,​T> unmarshaller​(Class<T> mappedType,
                                                                          ObjectCodec mapper)

    - #### unmarshaller

          public static <T> MaybeTransformer<Buffer,​T> unmarshaller​(TypeReference<T> mappedTypeRef,
                                                                          ObjectCodec mapper)