Either is a value of one of two possible types.

Inspired by Jeffrey van Gogh's discussion with the Rx.Net users, RxEither is a port of Scala's Either for the RxJava world.

• Progress reporting

  public class ProgressExample {
       public static void main(String[] args) {
              PublishSubject<Integer> progress = PublishSubject.create();
              Observable<String> results = Observable.fromCallable(() -> {
                  progress.onNext(0);
                  TimeUnit.SECONDS.sleep(1);
                  progress.onNext(100);
                  return "Hello, world!";
              }).subscribeOn(Schedulers.io());
              Observable<Either<Integer, String>> either = RxEither.from(progress, results).share();
              RxEither.filterLeft(either).subscribe(System.out::println);
              RxEither.filterRight(either).toBlocking().subscribe(System.out::println);
          }
  }

  Prints:

  0
  100
  Hello, world!
  

• Switch

  public class SwitchActionExample {
      public static void main(String[] args) {
          System.out.println("Type Either a string or an Int: ");
          String in = "";
          Either<String, Integer> either;
          try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
              in = reader.readLine();
              either = Either.right(Integer.parseInt(in));
          } catch (NumberFormatException | IOException e) {
              either = Either.left(in);
          }
          either.fold(
              s -> {
                  System.out.println("You passed me the String: " + s);
              },
              x -> {
                  System.out.println(
                          "You passed me the Int: " + x
                                  + ", which I will increment. " + x + " + 1 = "
                                  + (x + 1));
              });
      }
  }

  Prints:

  Type Either a string or an Int:
  1
  You passed me the Int: 1, which I will increment. 1 + 1 = 2
  

Maven:

<dependency>
  <groupId>net.jokubasdargis.rxeither</groupId>
  <artifactId>rxeither</artifactId>
  <version>1.2.0</version>
</dependency>

Gradle:

compile 'net.jokubasdargis.rxeither:rxeither:1.2.0'

Snapshots of the development version are available in Sonatype's snapshots repository.

Copyright 2016 Jokubas Dargis
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
   https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.