io.reactivex.Observable.single()方法的使用及代码示例

x33g5p2x  于2022-01-25 转载在 其他  
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本文整理了Java中io.reactivex.Observable.single()方法的一些代码示例，展示了Observable.single()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。Observable.single()方法的具体详情如下：
包路径：io.reactivex.Observable
类名称：Observable
方法名：single

Observable.single介绍

[英]Returns a Single that emits the single item emitted by this Observable, if this Observable emits only a single item, or a default item if the source ObservableSource emits no items. If the source ObservableSource emits more than one item, an IllegalArgumentException is signalled instead.

Scheduler: single does not operate by default on a particular Scheduler.
[中]如果此可观测对象仅发射单个项，则返回发射此可观测对象发射的单个项的单个项；如果源可观测源不发射任何项，则返回默认项。如果源ObservableSource发出多个项，则会发出IllegalArgumentException信号。
调度程序：默认情况下，single不会在特定调度程序上运行。

代码示例

代码示例来源：origin: ReactiveX/RxJava

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

代码示例来源：origin: ReactiveX/RxJava

  1. /**
  2.  * If this {@code Observable} completes after emitting a single item, return that item; if it emits
  3.  * more than one item, throw an {@code IllegalArgumentException}; if it emits no items, return a default
  4.  * value.
  5.  * <p>
  6.  * <img width="640" height="315" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/blockingSingleDefault.o.png" alt="">
  7.  * <dl>
  8.  *  <dt><b>Scheduler:</b></dt>
  9.  *  <dd>{@code blockingSingle} does not operate by default on a particular {@link Scheduler}.</dd>
  10.  *  <dt><b>Error handling:</b></dt>
  11.  *  <dd>If the source signals an error, the operator wraps a checked {@link Exception}
  12.  *  into {@link RuntimeException} and throws that. Otherwise, {@code RuntimeException}s and
  13.  *  {@link Error}s are rethrown as they are.</dd>
  14.  * </dl>
  15.  *
  16.  * @param defaultItem
  17.  *            a default value to return if this {@code Observable} emits no items
  18.  * @return the single item emitted by this {@code Observable}, or the default value if it emits no
  19.  *         items
  20.  * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
  21.  */
  22. @CheckReturnValue
  23. @SchedulerSupport(SchedulerSupport.NONE)
  24. public final T blockingSingle(T defaultItem) {
  25.   return single(defaultItem).blockingGet();
  26. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefault() {
  3.   Single<Integer> o = Observable.just(1).single(2);
  4.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  5.   o.subscribe(observer);
  6.   InOrder inOrder = inOrder(observer);
  7.   inOrder.verify(observer, times(1)).onSuccess(1);
  8.   inOrder.verifyNoMoreInteractions();
  9. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultObservable() {
  3.   Observable<Integer> o = Observable.just(1).single(2).toObservable();
  4.   Observer<Integer> observer = TestHelper.mockObserver();
  5.   o.subscribe(observer);
  6.   InOrder inOrder = inOrder(observer);
  7.   inOrder.verify(observer, times(1)).onNext(1);
  8.   inOrder.verify(observer, times(1)).onComplete();
  9.   inOrder.verifyNoMoreInteractions();
  10. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithTooManyElements() {
  3.   Single<Integer> o = Observable.just(1, 2).single(3);
  4.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  5.   o.subscribe(observer);
  6.   InOrder inOrder = inOrder(observer);
  7.   inOrder.verify(observer, times(1)).onError(
  8.       isA(IllegalArgumentException.class));
  9.   inOrder.verifyNoMoreInteractions();
  10. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithEmpty() {
  3.   Single<Integer> o = Observable.<Integer> empty()
  4.       .single(1);
  5.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  6.   o.subscribe(observer);
  7.   InOrder inOrder = inOrder(observer);
  8.   inOrder.verify(observer, times(1)).onSuccess(1);
  9.   inOrder.verifyNoMoreInteractions();
  10. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithTooManyElementsObservable() {
  3.   Observable<Integer> o = Observable.just(1, 2).single(3).toObservable();
  4.   Observer<Integer> observer = TestHelper.mockObserver();
  5.   o.subscribe(observer);
  6.   InOrder inOrder = inOrder(observer);
  7.   inOrder.verify(observer, times(1)).onError(
  8.       isA(IllegalArgumentException.class));
  9.   inOrder.verifyNoMoreInteractions();
  10. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithEmptyObservable() {
  3.   Observable<Integer> o = Observable.<Integer> empty()
  4.       .single(1).toObservable();
  5.   Observer<Integer> observer = TestHelper.mockObserver();
  6.   o.subscribe(observer);
  7.   InOrder inOrder = inOrder(observer);
  8.   inOrder.verify(observer, times(1)).onNext(1);
  9.   inOrder.verify(observer, times(1)).onComplete();
  10.   inOrder.verifyNoMoreInteractions();
  11. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicateAndEmpty() {
  3.   Single<Integer> o = Observable.just(1)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(2);
  11.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onSuccess(2);
  15.   inOrder.verifyNoMoreInteractions();
  16. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void singleDefault() {
  3.   Observable.just(1).single(100).test().assertResult(1);
  4.   Observable.empty().single(100).test().assertResult(100);
  5. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicate() {
  3.   Single<Integer> o = Observable.just(1, 2)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(4);
  11.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onSuccess(2);
  15.   inOrder.verifyNoMoreInteractions();
  16. }

代码示例来源：origin: redisson/redisson

  1. /**
  2.  * If this {@code Observable} completes after emitting a single item, return that item; if it emits
  3.  * more than one item, throw an {@code IllegalArgumentException}; if it emits no items, return a default
  4.  * value.
  5.  * <p>
  6.  * <img width="640" height="315" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/blockingSingleDefault.o.png" alt="">
  7.  * <dl>
  8.  *  <dt><b>Scheduler:</b></dt>
  9.  *  <dd>{@code blockingSingle} does not operate by default on a particular {@link Scheduler}.</dd>
  10.  *  <dt><b>Error handling:</b></dt>
  11.  *  <dd>If the source signals an error, the operator wraps a checked {@link Exception}
  12.  *  into {@link RuntimeException} and throws that. Otherwise, {@code RuntimeException}s and
  13.  *  {@link Error}s are rethrown as they are.</dd>
  14.  * </dl>
  15.  *
  16.  * @param defaultItem
  17.  *            a default value to return if this {@code Observable} emits no items
  18.  * @return the single item emitted by this {@code Observable}, or the default value if it emits no
  19.  *         items
  20.  * @see <a href="http://reactivex.io/documentation/operators/first.html">ReactiveX documentation: First</a>
  21.  */
  22. @CheckReturnValue
  23. @SchedulerSupport(SchedulerSupport.NONE)
  24. public final T blockingSingle(T defaultItem) {
  25.   return single(defaultItem).blockingGet();
  26. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicateObservable() {
  3.   Observable<Integer> o = Observable.just(1, 2)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(4).toObservable();
  11.   Observer<Integer> observer = TestHelper.mockObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onNext(2);
  15.   inOrder.verify(observer, times(1)).onComplete();
  16.   inOrder.verifyNoMoreInteractions();
  17. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicateAndEmptyObservable() {
  3.   Observable<Integer> o = Observable.just(1)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(2).toObservable();
  11.   Observer<Integer> observer = TestHelper.mockObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onNext(2);
  15.   inOrder.verify(observer, times(1)).onComplete();
  16.   inOrder.verifyNoMoreInteractions();
  17. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicateAndTooManyElements() {
  3.   Single<Integer> o = Observable.just(1, 2, 3, 4)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(6);
  11.   SingleObserver<Integer> observer = TestHelper.mockSingleObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onError(
  15.       isA(IllegalArgumentException.class));
  16.   inOrder.verifyNoMoreInteractions();
  17. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void testSingleOrDefaultWithPredicateAndTooManyElementsObservable() {
  3.   Observable<Integer> o = Observable.just(1, 2, 3, 4)
  4.       .filter(new Predicate<Integer>() {
  5.         @Override
  6.         public boolean test(Integer t1) {
  7.           return t1 % 2 == 0;
  8.         }
  9.       })
  10.       .single(6).toObservable();
  11.   Observer<Integer> observer = TestHelper.mockObserver();
  12.   o.subscribe(observer);
  13.   InOrder inOrder = inOrder(observer);
  14.   inOrder.verify(observer, times(1)).onError(
  15.       isA(IllegalArgumentException.class));
  16.   inOrder.verifyNoMoreInteractions();
  17. }

代码示例来源：origin: ReactiveX/RxJava

  1. @Test
  2. public void singleDefaultObservable() {
  3.   Observable.just(1).single(100).toObservable().test().assertResult(1);
  4.   Observable.empty().single(100).toObservable().test().assertResult(100);
  5. }

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