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

Observable.first介绍

[英]Returns an Observable that emits only the very first item emitted by the source Observable, or notifies of an NoSuchElementException if the source Observable is empty.

Scheduler: first does not operate by default on a particular Scheduler.
[中]返回一个Observable，该Observable只发出源Observable发出的第一个项，或者如果源Observable为空，则通知NoSuchElementException。
调度器：第一个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: jaydenxiao2016/AndroidFire

} else {
  return Observable.concat(fromCache, fromNetwork).first();

代码示例来源：origin: THEONE10211024/RxJavaSamples

@OnClick(R.id.btn_start_pseudo_cache)
public void onDemoPseudoCacheClicked() {
  _adapter = new ArrayAdapter<>(getActivity(),
     R.layout.item_log,
     R.id.item_log,
     new ArrayList<String>());
  _resultList.setAdapter(_adapter);
  _initializeCache();
  Observable.concat(_getCachedData(), _getFreshData())
      .first()
     .observeOn(AndroidSchedulers.mainThread())
     .subscribe(new Subscriber<Contributor>() {
       @Override
       public void onCompleted() {
         Timber.d("done loading all data");
       }
       @Override
       public void onError(Throwable e) {
         Timber.e(e, "arr something went wrong");
       }
       @Override
       public void onNext(Contributor contributor) {
         _contributionMap.put(contributor.login, contributor.contributions);
         _adapter.clear();
         _adapter.addAll(getListStringFromMap());
       }
     });
}

代码示例来源：origin: com.netflix.eureka/eureka2-test-utils

/**
 * Return {@link RxItem} that will give first value of the provided observable or will
 * time out. The timeout is measured from the time this method is called.
 */
public static <T> RxItem<T> firstFrom(long timeout, TimeUnit timeUnit, final Observable<T> observable) {
  return new SingleValueRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), observable.first());
}

代码示例来源：origin: com.netflix.eureka2/eureka-test-utils

/**
 * Return {@link RxItem} that will give first value of the provided observable or will
 * time out. The timeout is measured from the time this method is called.
 */
public static <T> RxItem<T> firstFrom(long timeout, TimeUnit timeUnit, final Observable<T> observable) {
  return new SingleValueRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), observable.first());
}

代码示例来源：origin: com.netflix.eureka2/eureka-test-utils

/**
 * Return {@link RxItem} that will give list of first values of the provided observables or will
 * time out. The timeout is measured from the time this method is called.
 */
public static <T> RxItem<List<T>> firstFromEach(long timeout, TimeUnit timeUnit, final Observable<T>... observables) {
  List<Observable<T>> firstItems = new ArrayList<Observable<T>>(observables.length);
  for (Observable<T> o : observables) {
    firstItems.add(o.first());
  }
  return new ListRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), firstItems);
}

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

@Override
 public void run() {
  Observable.range(1, 10).first().subscribe(new Action1<Integer>() {
   @Override
   public void call(Integer integer) {
    log(integer);
   }
  });
 }
});

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

/**
 * Returns the first item emitted by this {@code BlockingObservable}, or throws
 * {@code NoSuchElementException} if it emits no items.
 *
 * @return the first item emitted by this {@code BlockingObservable}
 * @throws NoSuchElementException
 *             if this {@code BlockingObservable} emits no items
 * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Blocking-Observable-Operators#first-and-firstordefault">RxJava Wiki: first()</a>
 * @see <a href="http://msdn.microsoft.com/en-us/library/hh229177.aspx">MSDN: Observable.First</a>
 */
public T first() {
  return blockForSingle(o.first());
}

代码示例来源：origin: com.netflix.eureka/eureka2-test-utils

/**
 * Return {@link RxItem} that will give list of first values of the provided observables or will
 * time out. The timeout is measured from the time this method is called.
 */
public static <T> RxItem<List<T>> firstFromEach(long timeout, TimeUnit timeUnit, final Observable<T>... observables) {
  List<Observable<T>> firstItems = new ArrayList<Observable<T>>(observables.length);
  for (Observable<T> o : observables) {
    firstItems.add(o.first());
  }
  return new ListRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), firstItems);
}

代码示例来源：origin: MaksTuev/ferro

/**
 * @return book with bookId
 */
public Observable<Book> getBook(String bookId) {
  return Observable.timer(3, TimeUnit.SECONDS)
      .flatMap(t -> Observable.from(books))
      .filter(book -> book.getId().equals(bookId))
      .first();
}

代码示例来源：origin: jacek-marchwicki/JavaWebsocketClient

@Nonnull
public Observable<DataMessage> sendMessageOnceWhenConnected(final Func1<String, Observable<Object>> createMessage) {
  return connectedAndRegistered
      .compose(isConnected())
      .first()
      .flatMap(new Func1<RxObjectEventConn, Observable<DataMessage>>() {
        @Override
        public Observable<DataMessage> call(final RxObjectEventConn rxEventConn) {
          return requestData(rxEventConn, createMessage);
        }
      });
}

代码示例来源：origin: NimbleDroid/FriendlyDemo

@NonNull
private Observable<List<Post>> getPostsFromDB() {
  return db.get().createQuery(TABLE_NAME, Post.SELECT_ALL)
      .mapToList(Post.MAPPER::map)
      .first();
}

代码示例来源：origin: Aptoide/aptoide-client-v8

public Single<Notification> getLastShowed(Integer[] notificationType) {
 return getAllSorted(Sort.DESCENDING, notificationType).first()
   .map(notifications -> {
    for (Notification notification : notifications) {
     if (!notification.isDismissed()) {
      return notification;
     }
    }
    return null;
   })
   .toSingle();
}

代码示例来源：origin: hantsy/spring-reactive-sample

Single<Post> findById(Long id) {
  return this.db.select("select * from posts where id=?")
    .parameter(id)
    .get(
      rs -> new Post(rs.getLong("id"),
        rs.getString("title"),
        rs.getString("content")
      )
    )
    .first()
    .toSingle();
}

代码示例来源：origin: bravekingzhang/CleanArch

@Override
  public Observable<List<SampleModel>> lists(int count, int page) {
    Realm realm = Realm.getDefaultInstance();
    Observable observable = realm.where(SampleModel.class).findAll().asObservable().map(new Func1<RealmResults<SampleModel>, List<SampleModel>>() {
      @Override
      public List<SampleModel> call(RealmResults<SampleModel> sampleModels) {
        return Converter.RealmResultList2SampleModel(sampleModels);
      }
    });
    return observable.first();
  }
//realm maybe have some bugs....,fuck

代码示例来源：origin: ArturVasilov/AndroidSchool

@Test
public void testSimpleObservable() throws Exception {
  Observable.just(5, 6, 7)
      .reduce((integer, integer2) -> integer + integer2)
      .first()
      .subscribe(integer -> assertEquals(18, integer.intValue()));
}

代码示例来源：origin: Aptoide/aptoide-client-v8

@Override public Completable removeDownload(String md5) {
 return downloadsRepository.getDownload(md5)
   .first()
   .flatMap(download -> getAppDownloader(download.getMd5()).flatMap(
     appDownloader -> appDownloader.removeAppDownload()
       .andThen(downloadsRepository.remove(md5))
       .andThen(Observable.just(download))))
   .doOnNext(download -> removeDownloadFiles(download))
   .toCompletable();
}

代码示例来源：origin: Aptoide/aptoide-client-v8

@Override public Completable pauseDownload(String md5) {
 return downloadsRepository.getDownload(md5)
   .first()
   .map(download -> {
    download.setOverallDownloadStatus(Download.PAUSED);
    downloadsRepository.save(download);
    return download;
   })
   .flatMap(download -> getAppDownloader(download.getMd5()))
   .flatMapCompletable(appDownloader -> appDownloader.pauseAppDownload())
   .toCompletable();
}

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

@Test
public void sample_161() throws Exception {
  Observable<Person> person = Observable.just(new Person());
  Observable<Income> income = person
      .flatMap(this::determineIncome)
      .flatMap(
          Observable::just,
          th -> Observable.empty(),
          Observable::empty)
      .concatWith(person.flatMap(this::guessIncome))
      .first();
}

代码示例来源：origin: Aptoide/aptoide-client-v8

private Observable<Download> handleDownloadProgress(AppDownloader appDownloader) {
 return appDownloader.observeDownloadProgress()
   .flatMap(appDownloadStatus -> downloadsRepository.getDownload(appDownloadStatus.getMd5())
     .first()
     .flatMap(download -> updateDownload(download, appDownloadStatus)))
   .filter(download -> download.getOverallDownloadStatus() == Download.COMPLETED)
   .doOnNext(download -> removeAppDownloader(download.getMd5()))
   .doOnNext(download -> downloadAnalytics.onDownloadComplete(download.getMd5(),
     download.getPackageName(), download.getVersionCode()))
   .takeUntil(download -> download.getOverallDownloadStatus() == Download.COMPLETED);
}

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

@Test
public void sample_570() throws Exception {
  Observable<Car> fromCache = loadFromCache();
  Observable<Car> fromDb = loadFromDb();
  Observable<Car> found = Observable
      .concat(fromCache, fromDb)
      .first();
}

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