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3.x update Conditional-and-Boolean-Operators.md (#7000)
* Fixed image link and added java examples * 3.x:Update Getting started docs * Conditional-and-Boolean-Operators documentation update
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| This section explains operators with which you conditionally emit or transform Observables, or can do boolean evaluations of them: | ||
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| ### Conditional Operators | ||
| * [**`amb( )`**](http://reactivex.io/documentation/operators/amb.html) — given two or more source Observables, emits all of the items from the first of these Observables to emit an item | ||
| * [**`defaultIfEmpty( )`**](http://reactivex.io/documentation/operators/defaultifempty.html) — emit items from the source Observable, or emit a default item if the source Observable completes after emitting no items | ||
| * (`rxjava-computation-expressions`) [**`doWhile( )`**](http://reactivex.io/documentation/operators/repeat.html) — emit the source Observable's sequence, and then repeat the sequence as long as a condition remains true | ||
| * (`rxjava-computation-expressions`) [**`ifThen( )`**](http://reactivex.io/documentation/operators/defer.html) — only emit the source Observable's sequence if a condition is true, otherwise emit an empty or default sequence | ||
| * [**`skipUntil( )`**](http://reactivex.io/documentation/operators/skipuntil.html) — discard items emitted by a source Observable until a second Observable emits an item, then emit the remainder of the source Observable's items | ||
| * [**`skipWhile( )`**](http://reactivex.io/documentation/operators/skipwhile.html) — discard items emitted by an Observable until a specified condition is false, then emit the remainder | ||
| * (`rxjava-computation-expressions`) [**`switchCase( )`**](http://reactivex.io/documentation/operators/defer.html) — emit the sequence from a particular Observable based on the results of an evaluation | ||
| * [**`takeUntil( )`**](http://reactivex.io/documentation/operators/takeuntil.html) — emits the items from the source Observable until a second Observable emits an item or issues a notification | ||
| * [**`takeWhile( )` and `takeWhileWithIndex( )`**](http://reactivex.io/documentation/operators/takewhile.html) — emit items emitted by an Observable as long as a specified condition is true, then skip the remainder | ||
| * (`rxjava-computation-expressions`) [**`whileDo( )`**](http://reactivex.io/documentation/operators/repeat.html) — if a condition is true, emit the source Observable's sequence and then repeat the sequence as long as the condition remains true | ||
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| > (`rxjava-computation-expressions`) — indicates that this operator is currently part of the optional `rxjava-computation-expressions` package under `rxjava-contrib` and is not included with the standard RxJava set of operators | ||
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| ### Outline | ||
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| - [`amb`](#all) | ||
| - [`defaultIfEmpty`](#defaultIfEmpty) | ||
| - [`skipUntil`](#skipUntil) | ||
| - [`skipWhile`](#skipWhile) | ||
| - [`takeUntil`](#takeUntil) | ||
| - [`takeWhile`](#takeUntil) | ||
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| ## amb | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/amb.html](http://reactivex.io/documentation/operators/amb.html) | ||
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| given two or more source Observables, emits all of the items from the first of these Observables to emit an item | ||
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| ```java | ||
| Observable source1 = Observable.range(1, 5); | ||
| Observable source2 = Observable.range(6, 5); | ||
| Observable.amb(new ArrayList(Arrays.asList(source1, source2))) | ||
| .subscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s\n", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
| ## defaultIfEmpty | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/defaultifempty.html](http://reactivex.io/documentation/operators/defaultifempty.html) | ||
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| emit items from the source Observable, or emit a default item if the source Observable completes after emitting no items | ||
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| ```java | ||
| Observable.empty().defaultIfEmpty(1).blockingSubscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
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| ## skipUntil | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/skipuntil.html](http://reactivex.io/documentation/operators/skipuntil.html) | ||
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| discard items emitted by a source Observable until a second Observable emits an item, then emit the remainder of the source Observable's items | ||
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| ```java | ||
| Observable observable1 = Observable.range(1, 10).doOnNext(next -> Thread.sleep(1000)); | ||
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| observable1.skipUntil(Observable.timer(3, TimeUnit.SECONDS)) | ||
| .subscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
| ## skipWhile | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/skipwhile.html](http://reactivex.io/documentation/operators/skipwhile.html) | ||
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| discard items emitted by an Observable until a specified condition is false, then emit the remainder | ||
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| ```java | ||
| Observable.range(1, 10).skipWhile(next -> next < 5) | ||
| .subscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
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| ## takeUntil | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/takeuntil.html](http://reactivex.io/documentation/operators/takeuntil.html) | ||
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| emits the items from the source Observable until a second Observable emits an item or issues a notification | ||
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| ```java | ||
| Observable.range(1, 10).takeUntil(value -> value >= 5) | ||
| .subscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
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| ## takeWhile | ||
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| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/takewhile.html](http://reactivex.io/documentation/operators/takewhile.html) | ||
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| emit items emitted by an Observable as long as a specified condition is true, then skip the remainder | ||
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| ```java | ||
| Observable.range(1, 10).takeWhile(value -> value <= 5) | ||
| .subscribe(next -> System.out.printf("next: %s\n", next), // onNext | ||
| throwable -> System.out.printf("error: %s", throwable), //onError | ||
| () -> System.out.println("Completed") //onComplete | ||
| ); | ||
| ``` | ||
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| ### Boolean Operators | ||
| * [**`all( )`**](http://reactivex.io/documentation/operators/all.html) — determine whether all items emitted by an Observable meet some criteria | ||
| * [**`contains( )`**](http://reactivex.io/documentation/operators/contains.html) — determine whether an Observable emits a particular item or not | ||
| * [**`exists( )` and `isEmpty( )`**](http://reactivex.io/documentation/operators/contains.html) — determine whether an Observable emits any items or not | ||
| * [**`sequenceEqual( )`**](http://reactivex.io/documentation/operators/sequenceequal.html) — test the equality of the sequences emitted by two Observables | ||
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| ### Outline | ||
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| - [`all`](#all) | ||
| - [`contains`](#contains) | ||
| - [`isEmpty`](#isEmpty) | ||
| - [`sequenceEqual`](#sequenceEqual) | ||
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| ## all | ||
| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/all.html](http://reactivex.io/documentation/operators/all.html) | ||
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| determine whether all items emitted by an Observable meet some criteria | ||
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| ```java | ||
| Flowable.range(0,10).doOnNext(next -> System.out.println(next)).all(integer -> integer<10). | ||
| blockingSubscribe(success->System.out.println("Success: "+success)); | ||
| ``` | ||
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| ## contains | ||
| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/contains.html](http://reactivex.io/documentation/operators/contains.html) | ||
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| determine whether an Observable emits a particular item or not | ||
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| ```java | ||
| Flowable.range(1,10).doOnNext(next->System.out.println(next)) | ||
| .contains(4).blockingSubscribe(contains->System.out.println("contains: "+contains)); | ||
| ``` | ||
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| ## isEmpty | ||
| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/contains.html](http://reactivex.io/documentation/operators/contains.html) | ||
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| determine whether the source Publisher is empty | ||
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| ```java | ||
| Flowable.empty().isEmpty().subscribe(isEmpty -> System.out.printf("isEmpty: %s", isEmpty)); | ||
| ``` | ||
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| ## sequenceEqual | ||
| **Available in:**  `Flowable`,  `Observable`,  `Maybe`,  `Single`,  `Completable` | ||
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| **ReactiveX documentation:** [http://reactivex.io/documentation/operators/sequenceequal.html](http://reactivex.io/documentation/operators/sequenceequal.html) | ||
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| test the equality of the sequences emitted by two Observables | ||
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| ```java | ||
| Flowable<Integer> flowable1 = Flowable.range(1,3).doOnNext(next-> System.out.print("flowable1: "+next + " ")); | ||
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| Flowable<Integer> flowable2 = Flowable.range(1,3).doOnNext(next-> System.out.println("flowable2: "+next)); | ||
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| Flowable.sequenceEqual(Flowable.fromPublisher(flowable1),Flowable.fromPublisher(flowable2)) | ||
| .blockingSubscribe(sequenceEqual->System.out.println("sequenceEqual: "+sequenceEqual)); | ||
| ``` |