io.reactivex.Flowable.switchIfEmpty()方法的使用及代码示例

x33g5p2x  于2022-01-19 转载在 其他  
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本文整理了Java中io.reactivex.Flowable.switchIfEmpty()方法的一些代码示例，展示了Flowable.switchIfEmpty()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Flowable.switchIfEmpty()方法的具体详情如下：
包路径：io.reactivex.Flowable
类名称：Flowable
方法名：switchIfEmpty

Flowable.switchIfEmpty介绍

[英]Returns a Flowable that emits the items emitted by the source Publisher or the items of an alternate Publisher if the source Publisher is empty.

Backpressure: If the source Publisher is empty, the alternate Publisher is expected to honor backpressure. If the source Publisher is non-empty, it is expected to honor backpressure as instead. In either case, if violated, a MissingBackpressureException may get signaled somewhere downstream. Scheduler: switchIfEmpty does not operate by default on a particular Scheduler.
[中]返回一个可流动项，该可流动项发出源发布服务器发出的项目，或者如果源发布服务器为空，则发出备用发布服务器的项目。
背压：如果源发布服务器为空，则备用发布服务器应接受背压。如果源发布服务器为非空，则应将背压作为默认值。在任何一种情况下，如果违反，可能会在下游某处发出缺失背压异常*的信号。Scheduler:switchIfEmpty默认情况下不会在特定计划程序上运行。

代码示例

代码示例来源：origin: ReactiveX/RxJava

  1. @Test(expected = NullPointerException.class)
  2. public void switchIfEmptyNull() {
  3.   just1.switchIfEmpty(null);
  4. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Override
  2.   public Publisher<Integer> createPublisher(long elements) {
  3.     return
  4.         Flowable.<Integer>empty().switchIfEmpty(Flowable.range(1, (int)elements))
  5.       ;
  6.   }
  7. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSwitchWhenEmpty() throws Exception {
  3.   final Flowable<Integer> flowable = Flowable.<Integer>empty()
  4.       .switchIfEmpty(Flowable.fromIterable(Arrays.asList(42)));
  5.   assertEquals(42, flowable.blockingSingle().intValue());
  6. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSwitchWhenNotEmpty() throws Exception {
  3.   final AtomicBoolean subscribed = new AtomicBoolean(false);
  4.   final Flowable<Integer> flowable = Flowable.just(4)
  5.       .switchIfEmpty(Flowable.just(2)
  6.       .doOnSubscribe(new Consumer<Subscription>() {
  7.         @Override
  8.         public void accept(Subscription s) {
  9.           subscribed.set(true);
  10.         }
  11.       }));
  12.   assertEquals(4, flowable.blockingSingle().intValue());
  13.   assertFalse(subscribed.get());
  14. }

代码示例来源：origin: ReactiveX/RxJava

  1. /**
  2.  * Returns a Flowable that emits the items emitted by the source Publisher or a specified default item
  3.  * if the source Publisher is empty.
  4.  * <p>
  5.  * <img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/defaultIfEmpty.png" alt="">
  6.  * <dl>
  7.  *  <dt><b>Backpressure:</b></dt>
  8.  *  <dd>If the source {@code Publisher} is empty, this operator is guaranteed to honor backpressure from downstream.
  9.  *  If the source {@code Publisher} is non-empty, it is expected to honor backpressure as well; if the rule is violated,
  10.  *  a {@code MissingBackpressureException} <em>may</em> get signaled somewhere downstream.
  11.  *  </dd>
  12.  *  <dt><b>Scheduler:</b></dt>
  13.  *  <dd>{@code defaultIfEmpty} does not operate by default on a particular {@link Scheduler}.</dd>
  14.  * </dl>
  15.  *
  16.  * @param defaultItem
  17.  *            the item to emit if the source Publisher emits no items
  18.  * @return a Flowable that emits either the specified default item if the source Publisher emits no
  19.  *         items, or the items emitted by the source Publisher
  20.  * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
  21.  */
  22. @CheckReturnValue
  23. @NonNull
  24. @BackpressureSupport(BackpressureKind.FULL)
  25. @SchedulerSupport(SchedulerSupport.NONE)
  26. public final Flowable<T> defaultIfEmpty(T defaultItem) {
  27.   ObjectHelper.requireNonNull(defaultItem, "item is null");
  28.   return switchIfEmpty(just(defaultItem));
  29. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSwitchWithProducer() throws Exception {
  3.   final AtomicBoolean emitted = new AtomicBoolean(false);
  4.   Flowable<Long> withProducer = Flowable.unsafeCreate(new Publisher<Long>() {
  5.     @Override
  6.     public void subscribe(final Subscriber<? super Long> subscriber) {
  7.       subscriber.onSubscribe(new Subscription() {
  8.         @Override
  9.         public void request(long n) {
  10.           if (n > 0 && emitted.compareAndSet(false, true)) {
  11.             emitted.set(true);
  12.             subscriber.onNext(42L);
  13.             subscriber.onComplete();
  14.           }
  15.         }
  16.         @Override
  17.         public void cancel() {
  18.         }
  19.       });
  20.     }
  21.   });
  22.   final Flowable<Long> flowable = Flowable.<Long>empty().switchIfEmpty(withProducer);
  23.   assertEquals(42, flowable.blockingSingle().intValue());
  24. }

代码示例来源：origin: redisson/redisson

  1. /**
  2.  * Returns a Flowable that emits the items emitted by the source Publisher or a specified default item
  3.  * if the source Publisher is empty.
  4.  * <p>
  5.  * <img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/defaultIfEmpty.png" alt="">
  6.  * <dl>
  7.  *  <dt><b>Backpressure:</b></dt>
  8.  *  <dd>If the source {@code Publisher} is empty, this operator is guaranteed to honor backpressure from downstream.
  9.  *  If the source {@code Publisher} is non-empty, it is expected to honor backpressure as well; if the rule is violated,
  10.  *  a {@code MissingBackpressureException} <em>may</em> get signaled somewhere downstream.
  11.  *  </dd>
  12.  *  <dt><b>Scheduler:</b></dt>
  13.  *  <dd>{@code defaultIfEmpty} does not operate by default on a particular {@link Scheduler}.</dd>
  14.  * </dl>
  15.  *
  16.  * @param defaultItem
  17.  *            the item to emit if the source Publisher emits no items
  18.  * @return a Flowable that emits either the specified default item if the source Publisher emits no
  19.  *         items, or the items emitted by the source Publisher
  20.  * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
  21.  */
  22. @CheckReturnValue
  23. @BackpressureSupport(BackpressureKind.FULL)
  24. @SchedulerSupport(SchedulerSupport.NONE)
  25. public final Flowable<T> defaultIfEmpty(T defaultItem) {
  26.   ObjectHelper.requireNonNull(defaultItem, "item is null");
  27.   return switchIfEmpty(just(defaultItem));
  28. }

代码示例来源：origin: micronaut-projects/micronaut-core

  1. ).switchIfEmpty(Flowable.error(new FunctionNotFoundException(functionName)));
  2. return serviceInstanceLocator.map(instance -> {
  3.   Optional<String> uri = instance.getMetadata().get(LocalFunctionRegistry.FUNCTION_PREFIX + functionName, String.class);

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testBackpressureNoRequest() {
  3.   TestSubscriber<Integer> ts = new TestSubscriber<Integer>(0L);
  4.   Flowable.<Integer>empty().switchIfEmpty(Flowable.just(1, 2, 3)).subscribe(ts);
  5.   ts.assertNoValues();
  6.   ts.assertNoErrors();
  7. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSwitchShouldNotTriggerUnsubscribe() {
  3.   final BooleanSubscription bs = new BooleanSubscription();
  4.   Flowable.unsafeCreate(new Publisher<Long>() {
  5.     @Override
  6.     public void subscribe(final Subscriber<? super Long> subscriber) {
  7.       subscriber.onSubscribe(bs);
  8.       subscriber.onComplete();
  9.     }
  10.   }).switchIfEmpty(Flowable.<Long>never()).subscribe();
  11.   assertFalse(bs.isCancelled());
  12. }

代码示例来源：origin: micronaut-projects/micronaut-core

  1. routePublisher = routePublisher.switchIfEmpty(Flowable.create((emitter) -> {
  2.   HttpRequest<?> httpRequest = requestReference.get();
  3.   MutableHttpResponse<?> response;

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSwitchRequestAlternativeObservableWithBackpressure() {
  3.   TestSubscriber<Integer> ts = new TestSubscriber<Integer>(1L);
  4.   Flowable.<Integer>empty().switchIfEmpty(Flowable.just(1, 2, 3)).subscribe(ts);
  5.   assertEquals(Arrays.asList(1), ts.values());
  6.   ts.assertNoErrors();
  7.   ts.request(1);
  8.   ts.assertValueCount(2);
  9.   ts.request(1);
  10.   ts.assertValueCount(3);
  11. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testBackpressureOnFirstObservable() {
  3.   TestSubscriber<Integer> ts = new TestSubscriber<Integer>(0L);
  4.   Flowable.just(1, 2, 3).switchIfEmpty(Flowable.just(4, 5, 6)).subscribe(ts);
  5.   ts.assertNotComplete();
  6.   ts.assertNoErrors();
  7.   ts.assertNoValues();
  8. }

代码示例来源：origin: micronaut-projects/micronaut-core

  1. setBodyContent(response, bodyContent)
  2. );
  3. return bodyToResponse.switchIfEmpty(Flowable.just(response));

代码示例来源：origin: ReactiveX/RxJava

  1. .switchIfEmpty(Flowable.fromIterable(Arrays.asList(1L, 2L, 3L)))
  2. .subscribeOn(Schedulers.computation())
  3. .subscribe(ts);

代码示例来源：origin: ReactiveX/RxJava

  1. .switchIfEmpty(withProducer)
  2.   .lift(new FlowableOperator<Long, Long>() {
  3. @Override

代码示例来源：origin: fengzhizi715/RxCache

  1. @Override
  2. public <T> Publisher<Record<T>> execute(RxCache rxCache, String key, Flowable<T> source, Type type) {
  3.   Flowable<Record<T>> cache = rxCache.<T>load2Flowable(key, type);
  4.   Flowable<Record<T>> remote = source
  5.       .map(new Function<T, Record<T>>() {
  6.         @Override
  7.         public Record<T> apply(@NonNull T t) throws Exception {
  8.           rxCache.save(key, t);
  9.           return new Record<>(Source.CLOUD, key, t);
  10.         }
  11.       });
  12.   return cache.switchIfEmpty(remote);
  13. }

代码示例来源：origin: fengzhizi715/RxCache

  1. @Override
  2. public <T> Publisher<Record<T>> execute(RxCache rxCache, String key, Flowable<T> source, Type type) {
  3.   Flowable<Record<T>> cache = rxCache.<T>load2Flowable(key, type);
  4.   Flowable<Record<T>> remote = source
  5.       .map(new Function<T, Record<T>>() {
  6.         @Override
  7.         public Record<T> apply(@NonNull T t) throws Exception {
  8.           rxCache.save(key, t);
  9.           return new Record<>(Source.CLOUD, key, t);
  10.         }
  11.       });
  12.   return remote.switchIfEmpty(cache);
  13. }

代码示例来源：origin: fengzhizi715/RxCache

  1. @Override
  2. public <T> Publisher<Record<T>> execute(RxCache rxCache, String key, Flowable<T> source, Type type) {
  3.   Flowable<Record<T>> cache = rxCache.<T>load2Flowable(key, type)
  4.       .filter(new Predicate<Record<T>>() {
  5.         @Override
  6.         public boolean test(Record<T> record) throws Exception {
  7.           return System.currentTimeMillis() - record.getCreateTime() <= timestamp;
  8.         }
  9.       });
  10.   Flowable<Record<T>> remote = source
  11.       .map(new Function<T, Record<T>>() {
  12.         @Override
  13.         public Record<T> apply(@NonNull T t) throws Exception {
  14.           rxCache.save(key, t);
  15.           return new Record<>(Source.CLOUD, key, t);
  16.         }
  17.       });
  18.   return cache.switchIfEmpty(remote);
  19. }

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