Tag: rxjava

Constructs a sequence from a pre-existing source or generator type.
Signals the items from a java.lang.Iterable source (such as Lists, Sets or Collections or custom Iterables) and then completes the sequence.

List<String> list = new ArrayList<>();
list.add("1");
list.add("2");
list.add("3");

Observable<String> observable = Observable.fromIterable(list);

observable.subscribe(s -> {
    System.out.println(s);
});

References
https://github.com/ReactiveX/RxJava/wiki/Creating-Observables#fromiterable

Constructs a reactive type by taking a pre-existing object and emitting that specific object to the downstream consumer upon subscription.

Observable<String> observable = Observable.just("1");

observable.subscribe(s -> {
    System.out.println(s);
});

Observable<String> observable = Observable.just("1", "2", "3", "4");

observable.subscribe(s -> {
    System.out.println(s);
});

References
https://github.com/ReactiveX/RxJava/wiki/Creating-Observables#just

Construct a safe reactive type instance which when subscribed to by a consumer, runs an user-provided function and provides a type-specific Emitter for this function to generate the signal(s) the designated business logic requires. This method allows bridging the non-reactive, usually listener/callback-style world, with the reactive world.

Observable<String> observable = Observable.create(emitter -> {
    emitter.onNext("1");
    emitter.onNext("2");
    emitter.onComplete();
});

observable.subscribe(s -> {
    System.out.println(s);
});

References
https://www.vogella.com/tutorials/RxJava/article.html#creating-observables
https://www.tutorialspoint.com/rxjava/rxjava_creating_operators.htm
https://github.com/ReactiveX/RxJava/wiki/Creating-Observables#create