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

Observable.switchIfEmpty介绍

[英]Returns an Observable that emits the items emitted by the source ObservableSource or the items of an alternate ObservableSource if the source ObservableSource is empty.

Scheduler: switchIfEmpty does not operate by default on a particular Scheduler.
[中]返回一个ObservableSource，该ObservableSource发出源ObservableSource发出的项，如果源ObservableSource为空，则返回备用ObservableSource发出的项。
调度器：switchIfEmpty默认情况下不会在特定的调度器上运行。

代码示例

代码示例来源：origin: ReactiveX/RxJava

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

代码示例来源：origin: ReactiveX/RxJava

/**
 * Returns an Observable that emits the items emitted by the source ObservableSource or a specified default item
 * if the source ObservableSource is empty.
 * <p>
 * <img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/defaultIfEmpty.png" alt="">
 * <dl>
 *  <dt><b>Scheduler:</b></dt>
 *  <dd>{@code defaultIfEmpty} does not operate by default on a particular {@link Scheduler}.</dd>
 * </dl>
 *
 * @param defaultItem
 *            the item to emit if the source ObservableSource emits no items
 * @return an Observable that emits either the specified default item if the source ObservableSource emits no
 *         items, or the items emitted by the source ObservableSource
 * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
 */
@CheckReturnValue
@SchedulerSupport(SchedulerSupport.NONE)
public final Observable<T> defaultIfEmpty(T defaultItem) {
  ObjectHelper.requireNonNull(defaultItem, "defaultItem is null");
  return switchIfEmpty(just(defaultItem));
}

代码示例来源：origin: redisson/redisson

/**
 * Returns an Observable that emits the items emitted by the source ObservableSource or a specified default item
 * if the source ObservableSource is empty.
 * <p>
 * <img width="640" height="305" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/defaultIfEmpty.png" alt="">
 * <dl>
 *  <dt><b>Scheduler:</b></dt>
 *  <dd>{@code defaultIfEmpty} does not operate by default on a particular {@link Scheduler}.</dd>
 * </dl>
 *
 * @param defaultItem
 *            the item to emit if the source ObservableSource emits no items
 * @return an Observable that emits either the specified default item if the source ObservableSource emits no
 *         items, or the items emitted by the source ObservableSource
 * @see <a href="http://reactivex.io/documentation/operators/defaultifempty.html">ReactiveX operators documentation: DefaultIfEmpty</a>
 */
@CheckReturnValue
@SchedulerSupport(SchedulerSupport.NONE)
public final Observable<T> defaultIfEmpty(T defaultItem) {
  ObjectHelper.requireNonNull(defaultItem, "defaultItem is null");
  return switchIfEmpty(just(defaultItem));
}

代码示例来源：origin: ReactiveX/RxJava

@Test
public void testSwitchWhenNotEmpty() throws Exception {
  final AtomicBoolean subscribed = new AtomicBoolean(false);
  final Observable<Integer> o = Observable.just(4)
      .switchIfEmpty(Observable.just(2)
      .doOnSubscribe(new Consumer<Disposable>() {
        @Override
        public void accept(Disposable d) {
          subscribed.set(true);
        }
      }));
  assertEquals(4, o.blockingSingle().intValue());
  assertFalse(subscribed.get());
}

代码示例来源：origin: ReactiveX/RxJava

@Test
public void testSwitchWhenEmpty() throws Exception {
  final Observable<Integer> o = Observable.<Integer>empty()
      .switchIfEmpty(Observable.fromIterable(Arrays.asList(42)));
  assertEquals(42, o.blockingSingle().intValue());
}

代码示例来源：origin: ReactiveX/RxJava

@Test
  public void testSwitchShouldTriggerUnsubscribe() {
    final Disposable d = Disposables.empty();

    Observable.unsafeCreate(new ObservableSource<Long>() {
      @Override
      public void subscribe(final Observer<? super Long> observer) {
        observer.onSubscribe(d);
        observer.onComplete();
      }
    }).switchIfEmpty(Observable.<Long>never()).subscribe();
    assertTrue(d.isDisposed());
  }
}

代码示例来源：origin: ReactiveX/RxJava

.switchIfEmpty(withProducer)
  .lift(new ObservableOperator<Long, Long>() {
@Override

代码示例来源：origin: GrossumUA/TAS_Android_Boilerplate

/**
 * Replaces observable of objects with observable of optionals.
 * Result observable always contains optionals, Optional.empty() if source observable has no items.
 */
public static <T> Observable<Optional<T>> toOptObs(Observable<T> source) {
  return source.map(Optional::ofNullable)
    .switchIfEmpty(just(Optional.empty()));
}

代码示例来源：origin: fengzhizi715/RxCache

@Override
  public <T> Observable<Record<T>> execute(RxCache rxCache, String key, Observable<T> source, Type type) {

    Observable<Record<T>> cache = rxCache.<T>load2Observable(key, type);

    Observable<Record<T>> remote = source
        .map(new Function<T, Record<T>>() {
          @Override
          public Record<T> apply(@NonNull T t) throws Exception {

            rxCache.save(key, t);

            return new Record<>(Source.CLOUD, key, t);
          }
        });

    return cache.switchIfEmpty(remote);
  }
}

代码示例来源：origin: fengzhizi715/RxCache

@Override
  public <T> Observable<Record<T>> execute(RxCache rxCache, String key, Observable<T> source, Type type) {

    Observable<Record<T>> cache = rxCache.<T>load2Observable(key, type);

    Observable<Record<T>> remote = source
        .map(new Function<T, Record<T>>() {
          @Override
          public Record<T> apply(@NonNull T t) throws Exception {

            rxCache.save(key, t);

            return new Record<>(Source.CLOUD, key, t);
          }
        });

    return remote.switchIfEmpty(cache);
  }
}

代码示例来源：origin: WallaceXiao/StockChart-MPAndroidChart

@Override
  public <T> Observable<CacheResult<T>> execute(RxCache rxCache, String key, long time, Observable<T> source, Type type) {
    Observable<CacheResult<T>> cache = loadCache(rxCache, type, key, time, true);
    Observable<CacheResult<T>> remote = loadRemote(rxCache, key, source, false);
    return cache.switchIfEmpty(remote);
  }
}

代码示例来源：origin: TetraTutorials/clean-android

@Override
  public Observable<Result> getResultData() {
    return getResultsFromMemory().switchIfEmpty(getResultsFromNetwork());
  }
}

代码示例来源：origin: TetraTutorials/clean-android

@Override
public Observable<String> getCountryData() {
  return getCountriesFromMemory().switchIfEmpty(getCountriesFromNetwork());
}

代码示例来源：origin: fengzhizi715/RxCache

@Override
  public <T> Observable<Record<T>> execute(RxCache rxCache, String key, Observable<T> source, Type type) {

    Observable<Record<T>> cache = rxCache.<T>load2Observable(key, type)
        .filter(new Predicate<Record<T>>() {
          @Override
          public boolean test(Record<T> record) throws Exception {
            return System.currentTimeMillis() - record.getCreateTime() <= timestamp;
          }
        });

    Observable<Record<T>> remote = source
        .map(new Function<T, Record<T>>() {
          @Override
          public Record<T> apply(@NonNull T t) throws Exception {

            rxCache.save(key, t);

            return new Record<>(Source.CLOUD, key, t);
          }
        });

    return cache.switchIfEmpty(remote);
  }
}

代码示例来源：origin: io.gravitee.am.gateway.handlers/gravitee-am-gateway-handler

public Single<Token> grant(TokenRequest tokenRequest, Client client) {
  return Observable
      .fromIterable(tokenGranters.values())
      .filter(tokenGranter -> tokenGranter.handle(tokenRequest.getGrantType()))
      .switchIfEmpty(Observable.error(new UnsupportedGrantTypeException("Unsupported grant type: " + tokenRequest.getGrantType())))
      .flatMapSingle(tokenGranter -> tokenGranter.grant(tokenRequest, client)).singleOrError();
}

代码示例来源：origin: gravitee-io/graviteeio-access-management

public Single<Token> grant(TokenRequest tokenRequest, Client client) {
  return Observable
      .fromIterable(tokenGranters.values())
      .filter(tokenGranter -> tokenGranter.handle(tokenRequest.getGrantType()))
      .switchIfEmpty(Observable.error(new UnsupportedGrantTypeException("Unsupported grant type: " + tokenRequest.getGrantType())))
      .flatMapSingle(tokenGranter -> tokenGranter.grant(tokenRequest, client)).singleOrError();
}

代码示例来源：origin: gravitee-io/graviteeio-access-management

@Override
public Single<AuthorizationResponse> run(AuthorizationRequest authorizationRequest, Client client, User endUser) {
  return Observable
      .fromIterable(flows)
      .filter(flow -> flow.handle(authorizationRequest.getResponseType()))
      .switchIfEmpty(Observable.error(new UnsupportedResponseTypeException("Unsupported response type: " + authorizationRequest.getResponseType())))
      .flatMapSingle(flow -> flow.run(authorizationRequest, client, endUser)).singleOrError();
}

代码示例来源：origin: io.gravitee.am.gateway.handlers/gravitee-am-gateway-handler

@Override
public Single<AuthorizationResponse> run(AuthorizationRequest authorizationRequest, Client client, User endUser) {
  return Observable
      .fromIterable(flows)
      .filter(flow -> flow.handle(authorizationRequest.getResponseType()))
      .switchIfEmpty(Observable.error(new UnsupportedResponseTypeException("Unsupported response type: " + authorizationRequest.getResponseType())))
      .flatMapSingle(flow -> flow.run(authorizationRequest, client, endUser)).singleOrError();
}

代码示例来源：origin: com.firstdata.clovergo/domain

}).switchIfEmpty(Observable.<EmployeeMerchant>error(new Error("no_employee_to_set_passcode", "PassCode set failed please re-activate")));

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