rx.Observable.singleOrDefault()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rx.Observable.singleOrDefault()方法的一些代码示例，展示了Observable.singleOrDefault()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.singleOrDefault()方法的具体详情如下：
包路径：rx.Observable
类名称：Observable
方法名：singleOrDefault

Observable.singleOrDefault介绍

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

Scheduler: singleOrDefault does not operate by default on a particular Scheduler.
[中]如果源可观测对象仅发射单个项，则返回发射源可观测对象发射的单个项的可观测对象；如果源可观测对象未发射任何项，则返回默认项。如果源Observable发出多个项，则抛出IllegalArgumentException。
调度程序：默认情况下，singleOrDefault不会在特定调度程序上运行。

代码示例

代码示例来源：origin: jooby-project/jooby

  1. @Override
  2. public <T> Observable<List<T>> query(final N1qlQuery query) {
  3.  return bucket.query(query)
  4.    .flatMap(aqr -> Observable.zip(aqr.rows().toList(),
  5.      aqr.errors().toList(),
  6.      aqr.finalSuccess().singleOrDefault(Boolean.FALSE),
  7.      (rows, errors, finalSuccess) -> {
  8.       if (!finalSuccess) {
  9.        throw new QueryExecutionException(
  10.          "execution of query resulted in exception: ",
  11.          Try.apply(() -> errors.get(0)).orElse(null));
  12.       }
  13.       List<T> value = new ArrayList<>();
  14.       for (AsyncN1qlQueryRow row : rows) {
  15.        try {
  16.         T v = converter.fromBytes(row.byteValue());
  17.         value.add(v);
  18.        } catch (IOException ex) {
  19.         throw new QueryExecutionException(
  20.           "execution of query resulted in exception", null, ex);
  21.        }
  22.       }
  23.       return value;
  24.      }));
  25. }

代码示例来源：origin: leeowenowen/rxjava-examples

  1. @Override
  2.  public void run() {
  3.   Observable.<Integer>empty().singleOrDefault(10).subscribe(new Action1<Integer>() {
  4.    @Override
  5.    public void call(Integer integer) {
  6.     log(integer);
  7.    }
  8.   });
  9.  }
  10. });

代码示例来源：origin: alex-shpak/rx-jersey

  1. @Override
  2.   public Single convert(Observable<?> result) throws Throwable {
  3.     return result.singleOrDefault(null).toSingle();
  4.   }
  5. }

代码示例来源：origin: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * Returns an Observable that emits only the very first item emitted by the source Observable, or a default
  3.  * item if the source Observable completes without emitting anything.
  4.  * <p>
  5.  * <img width="640" height="305" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/firstOrDefault.png" alt="">
  6.  * <dl>
  7.  *  <dt><b>Scheduler:</b></dt>
  8.  *  <dd>{@code firstOrDefault} does not operate by default on a particular {@link Scheduler}.</dd>
  9.  * </dl>
  10.  * 
  11.  * @param defaultValue
  12.  *            the default item to emit if the source Observable doesn't emit anything
  13.  * @return an Observable that emits only the very first item from the source, or a default item if the
  14.  *         source Observable completes without emitting any items
  15.  * @see <a href="https://github.com/Netflix/RxJava/wiki/Filtering-Observables#firstordefault">RxJava wiki: firstOrDefault</a>
  16.  * @see "MSDN: Observable.firstOrDefaultAsync"
  17.  */
  18. public final Observable<T> firstOrDefault(T defaultValue) {
  19.   return take(1).singleOrDefault(defaultValue);
  20. }

代码示例来源：origin: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * Returns an Observable that emits only the last item emitted by the source Observable, or a default item
  3.  * if the source Observable completes without emitting any items.
  4.  * <p>
  5.  * <img width="640" height="305" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/lastOrDefault.png" alt="">
  6.  * <dl>
  7.  *  <dt><b>Scheduler:</b></dt>
  8.  *  <dd>{@code lastOrDefault} does not operate by default on a particular {@link Scheduler}.</dd>
  9.  * </dl>
  10.  * 
  11.  * @param defaultValue
  12.  *            the default item to emit if the source Observable is empty
  13.  * @return an Observable that emits only the last item emitted by the source Observable, or a default item
  14.  *         if the source Observable is empty
  15.  * @see <a href="https://github.com/Netflix/RxJava/wiki/Filtering-Observables#lastordefault">RxJava wiki: lastOrDefault</a>
  16.  * @see "MSDN: Observable.lastOrDefaultAsync"
  17.  */
  18. public final Observable<T> lastOrDefault(T defaultValue) {
  19.   return takeLast(1).singleOrDefault(defaultValue);
  20. }

代码示例来源：origin: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * Returns an Observable that emits only the very first item emitted by the source Observable that satisfies
  3.  * a specified condition, or a default item if the source Observable emits no such items.
  4.  * <p>
  5.  * <img width="640" height="310" src="https://raw.github.com/wiki/Netflix/RxJava/images/rx-operators/firstOrDefaultN.png" alt="">
  6.  * <dl>
  7.  *  <dt><b>Scheduler:</b></dt>
  8.  *  <dd>{@code firstOrDefault} does not operate by default on a particular {@link Scheduler}.</dd>
  9.  * </dl>
  10.  * 
  11.  * @param predicate
  12.  *            the condition any item emitted by the source Observable has to satisfy
  13.  * @param defaultValue
  14.  *            the default item to emit if the source Observable doesn't emit anything that satisfies the
  15.  *            {@code predicate}
  16.  * @return an Observable that emits only the very first item emitted by the source Observable that satisfies
  17.  *         the {@code predicate}, or a default item if the source Observable emits no such items
  18.  * @see <a href="https://github.com/Netflix/RxJava/wiki/Filtering-Observables#firstordefault">RxJava wiki: firstOrDefault</a>
  19.  * @see "MSDN: Observable.firstOrDefaultAsync"
  20.  */
  21. public final Observable<T> firstOrDefault(T defaultValue, Func1<? super T, Boolean> predicate) {
  22.   return takeFirst(predicate).singleOrDefault(defaultValue);
  23. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public DesignDocument getDesignDocument(final String name, final long timeout, final TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(
  4.     asyncBucketManager.getDesignDocument(name).singleOrDefault(null), timeout, timeUnit
  5.   );
  6. }

代码示例来源：origin: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * If this {@code BlockingObservable} completes after emitting a single item that matches a predicate,
  3.  * return that item; if it emits more than one such item, throw an {@code IllegalArgumentException}; if it
  4.  * emits no items, return a default value.
  5.  * <p>
  6.  * <img width="640" height="315" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/B.singleOrDefault.p.png" alt="">
  7.  *
  8.  * @param defaultValue
  9.  *            a default value to return if this {@code BlockingObservable} emits no matching items
  10.  * @param predicate
  11.  *            a predicate function to evaluate items emitted by this {@code BlockingObservable}
  12.  * @return the single item emitted by the {@code BlockingObservable} that matches the predicate, or the
  13.  *         default value if no such items are emitted
  14.  * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Blocking-Observable-Operators#single-and-singleordefault">RxJava Wiki: singleOrDefault()</a>
  15.  * @see <a href="http://msdn.microsoft.com/en-us/library/system.reactive.linq.observable.singleordefault.aspx">MSDN: Observable.SingleOrDefault</a>
  16.  */
  17. public T singleOrDefault(T defaultValue, Func1<? super T, Boolean> predicate) {
  18.   return blockForSingle(o.filter(predicate).map(Functions.<T>identity()).singleOrDefault(defaultValue));
  19. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public DesignDocument getDesignDocument(final String name, final boolean development, final long timeout,
  3.   final TimeUnit timeUnit) {
  4.   return Blocking.blockForSingle(
  5.     asyncBucketManager.getDesignDocument(name, development).singleOrDefault(null), timeout, timeUnit
  6.   );
  7. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public BucketSettings getBucket(String name, long timeout, TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(asyncClusterManager.getBucket(name).singleOrDefault(null), timeout, timeUnit);
  4. }

代码示例来源：origin: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * If this {@code BlockingObservable} 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/B.singleOrDefault.png" alt="">
  7.  *
  8.  * @param defaultValue
  9.  *            a default value to return if this {@code BlockingObservable} emits no items
  10.  * @return the single item emitted by this {@code BlockingObservable}, or the default value if it emits no
  11.  *         items
  12.  * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Blocking-Observable-Operators#single-and-singleordefault">RxJava Wiki: singleOrDefault()</a>
  13.  * @see <a href="http://msdn.microsoft.com/en-us/library/system.reactive.linq.observable.singleordefault.aspx">MSDN: Observable.SingleOrDefault</a>
  14.  */
  15. public T singleOrDefault(T defaultValue) {
  16.   return blockForSingle(o.map(Functions.<T>identity()).singleOrDefault(defaultValue));
  17. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public JsonDocument document(long timeout, TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(asyncViewRow.document().singleOrDefault(null), timeout, timeUnit);
  4. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public <D extends Document<?>> D document(Class<D> target, long timeout, TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(asyncViewRow.document(target).singleOrDefault(null), timeout, timeUnit);
  4. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public JsonDocument document(long timeout, TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(asyncViewRow.document().singleOrDefault(null), timeout, timeUnit);
  4. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2. public <D extends Document<?>> D document(Class<D> target, long timeout, TimeUnit timeUnit) {
  3.   return Blocking.blockForSingle(asyncViewRow.document(target).singleOrDefault(null), timeout, timeUnit);
  4. }

代码示例来源：origin: com.couchbase.client/java-client

  1. /**
  2.  * Maps a raw {@link ViewQueryResponse} into a {@link AsyncViewResult}.
  3.  *
  4.  * @param bucket reference to the bucket.
  5.  * @param query the original query object.
  6.  * @param response the response from the server.
  7.  * @return a converted {@link AsyncViewResult}.
  8.  */
  9. public static Observable<AsyncViewResult> mapToViewResult(final AsyncBucket bucket, final ViewQuery query,
  10.   final ViewQueryResponse response) {
  11.   return response
  12.     .info()
  13.     .singleOrDefault(null)
  14.     .map(new ByteBufToJsonObject())
  15.     .map(new BuildViewResult(bucket, query, response));
  16. }

代码示例来源：origin: com.couchbase.client/java-client

  1. /**
  2.  * Maps a raw {@link ViewQueryResponse} into a {@link AsyncSpatialViewResult}.
  3.  *
  4.  * @param bucket reference to the bucket.
  5.  * @param query the original query object.
  6.  * @param response the response from the server.
  7.  * @return a converted {@link AsyncSpatialViewResult}.
  8.  */
  9. public static Observable<AsyncSpatialViewResult> mapToSpatialViewResult(final AsyncBucket bucket,
  10.   final SpatialViewQuery query, final ViewQueryResponse response) {
  11.   return response
  12.     .info()
  13.     .singleOrDefault(null)
  14.     .map(new ByteBufToJsonObject())
  15.     .map(new BuildSpatialViewResult(bucket, query, response));
  16. }

代码示例来源：origin: nurkiewicz/rxjava-book-examples

  1. default Observable<Integer> populationOf(String query) {
  2.   return search(query)
  3.       .concatMapIterable(SearchResult::getGeonames)
  4.       .map(Geoname::getPopulation)
  5.       .filter(p -> p != null)
  6.       .singleOrDefault(0)
  7.       .doOnError(th ->
  8.           log.warn("Falling back to 0 for {}", query, th))
  9.       .onErrorReturn(th -> 0)
  10.       .subscribeOn(Schedulers.io());
  11. }

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2.   public Observable<AnalyticsQueryResult> call(final AsyncAnalyticsQueryResult aqr) {
  3.     final boolean parseSuccess = aqr.parseSuccess();
  4.     final String requestId = aqr.requestId();
  5.     final String clientContextId = aqr.clientContextId();
  6.     return Observable.zip(aqr.signature().singleOrDefault(JsonObject.empty()),
  7.         aqr.info().singleOrDefault(AnalyticsMetrics.EMPTY_METRICS),
  8.         aqr.errors().toList(),
  9.         aqr.status(),
  10.         aqr.finalSuccess().singleOrDefault(Boolean.FALSE),
  11.         new Func5<Object, AnalyticsMetrics, List<JsonObject>, String, Boolean, AnalyticsQueryResult>() {
  12.           @Override
  13.           public AnalyticsQueryResult call(Object signature, AnalyticsMetrics info, List<JsonObject> errors, String finalStatus, Boolean finalSuccess) {
  14.             return new DefaultAnalyticsQueryResult(aqr.handle(), signature, info, errors, finalStatus, finalSuccess,
  15.                 parseSuccess, requestId, clientContextId);
  16.           }
  17.         });
  18.   }
  19. };

代码示例来源：origin: com.couchbase.client/java-client

  1. @Override
  2.   public Observable<AnalyticsQueryResult> call(AsyncAnalyticsQueryResult aqr) {
  3.     final boolean parseSuccess = aqr.parseSuccess();
  4.     final String requestId = aqr.requestId();
  5.     final String clientContextId = aqr.clientContextId();
  6.     return Observable.zip(aqr.rows().toList(),
  7.       aqr.signature().singleOrDefault(JsonObject.empty()),
  8.       aqr.info().singleOrDefault(AnalyticsMetrics.EMPTY_METRICS),
  9.       aqr.errors().toList(),
  10.       aqr.status(),
  11.       aqr.finalSuccess().singleOrDefault(Boolean.FALSE),
  12.       new Func6<List<AsyncAnalyticsQueryRow>, Object, AnalyticsMetrics, List<JsonObject>, String, Boolean, AnalyticsQueryResult>() {
  13.         @Override
  14.         public AnalyticsQueryResult call(List<AsyncAnalyticsQueryRow> rows, Object signature,
  15.           AnalyticsMetrics info, List<JsonObject> errors, String finalStatus, Boolean finalSuccess) {
  16.           return new DefaultAnalyticsQueryResult(rows, signature, info, errors, finalStatus, finalSuccess,
  17.             parseSuccess, requestId, clientContextId);
  18.         }
  19.       });
  20.   }
  21. };

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