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

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

代码示例来源：origin: THEONE10211024/RxJavaSamples

  1. @OnClick(R.id.btn_start_pseudo_cache)
  2. public void onDemoPseudoCacheClicked() {
  3.   _adapter = new ArrayAdapter<>(getActivity(),
  4.      R.layout.item_log,
  5.      R.id.item_log,
  6.      new ArrayList<String>());
  7.   _resultList.setAdapter(_adapter);
  8.   _initializeCache();
  9.   Observable.concat(_getCachedData(), _getFreshData())
  10.       .first()
  11.      .observeOn(AndroidSchedulers.mainThread())
  12.      .subscribe(new Subscriber<Contributor>() {
  13.        @Override
  14.        public void onCompleted() {
  15.          Timber.d("done loading all data");
  16.        }
  17.        @Override
  18.        public void onError(Throwable e) {
  19.          Timber.e(e, "arr something went wrong");
  20.        }
  21.        @Override
  22.        public void onNext(Contributor contributor) {
  23.          _contributionMap.put(contributor.login, contributor.contributions);
  24.          _adapter.clear();
  25.          _adapter.addAll(getListStringFromMap());
  26.        }
  27.      });
  28. }

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

  1. /**
  2.  * Return {@link RxItem} that will give first value of the provided observable or will
  3.  * time out. The timeout is measured from the time this method is called.
  4.  */
  5. public static <T> RxItem<T> firstFrom(long timeout, TimeUnit timeUnit, final Observable<T> observable) {
  6.   return new SingleValueRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), observable.first());
  7. }

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

  1. /**
  2.  * Return {@link RxItem} that will give first value of the provided observable or will
  3.  * time out. The timeout is measured from the time this method is called.
  4.  */
  5. public static <T> RxItem<T> firstFrom(long timeout, TimeUnit timeUnit, final Observable<T> observable) {
  6.   return new SingleValueRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), observable.first());
  7. }

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

  1. /**
  2.  * Return {@link RxItem} that will give list of first values of the provided observables or will
  3.  * time out. The timeout is measured from the time this method is called.
  4.  */
  5. public static <T> RxItem<List<T>> firstFromEach(long timeout, TimeUnit timeUnit, final Observable<T>... observables) {
  6.   List<Observable<T>> firstItems = new ArrayList<Observable<T>>(observables.length);
  7.   for (Observable<T> o : observables) {
  8.     firstItems.add(o.first());
  9.   }
  10.   return new ListRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), firstItems);
  11. }

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

  1. @Override
  2.  public void run() {
  3.   Observable.range(1, 10).first().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: com.netflix.rxjava/rxjava-core

  1. /**
  2.  * Returns the first item emitted by this {@code BlockingObservable}, or throws
  3.  * {@code NoSuchElementException} if it emits no items.
  4.  *
  5.  * @return the first item emitted by this {@code BlockingObservable}
  6.  * @throws NoSuchElementException
  7.  *             if this {@code BlockingObservable} emits no items
  8.  * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Blocking-Observable-Operators#first-and-firstordefault">RxJava Wiki: first()</a>
  9.  * @see <a href="http://msdn.microsoft.com/en-us/library/hh229177.aspx">MSDN: Observable.First</a>
  10.  */
  11. public T first() {
  12.   return blockForSingle(o.first());
  13. }

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

  1. /**
  2.  * Return {@link RxItem} that will give list of first values of the provided observables or will
  3.  * time out. The timeout is measured from the time this method is called.
  4.  */
  5. public static <T> RxItem<List<T>> firstFromEach(long timeout, TimeUnit timeUnit, final Observable<T>... observables) {
  6.   List<Observable<T>> firstItems = new ArrayList<Observable<T>>(observables.length);
  7.   for (Observable<T> o : observables) {
  8.     firstItems.add(o.first());
  9.   }
  10.   return new ListRxItem<T>(TimeUnit.MILLISECONDS.convert(timeout, timeUnit), firstItems);
  11. }

代码示例来源：origin: MaksTuev/ferro

  1. /**
  2.  * @return book with bookId
  3.  */
  4. public Observable<Book> getBook(String bookId) {
  5.   return Observable.timer(3, TimeUnit.SECONDS)
  6.       .flatMap(t -> Observable.from(books))
  7.       .filter(book -> book.getId().equals(bookId))
  8.       .first();
  9. }

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

  1. @Nonnull
  2. public Observable<DataMessage> sendMessageOnceWhenConnected(final Func1<String, Observable<Object>> createMessage) {
  3.   return connectedAndRegistered
  4.       .compose(isConnected())
  5.       .first()
  6.       .flatMap(new Func1<RxObjectEventConn, Observable<DataMessage>>() {
  7.         @Override
  8.         public Observable<DataMessage> call(final RxObjectEventConn rxEventConn) {
  9.           return requestData(rxEventConn, createMessage);
  10.         }
  11.       });
  12. }

代码示例来源：origin: NimbleDroid/FriendlyDemo

  1. @NonNull
  2. private Observable<List<Post>> getPostsFromDB() {
  3.   return db.get().createQuery(TABLE_NAME, Post.SELECT_ALL)
  4.       .mapToList(Post.MAPPER::map)
  5.       .first();
  6. }

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

  1. public Single<Notification> getLastShowed(Integer[] notificationType) {
  2.  return getAllSorted(Sort.DESCENDING, notificationType).first()
  3.    .map(notifications -> {
  4.     for (Notification notification : notifications) {
  5.      if (!notification.isDismissed()) {
  6.       return notification;
  7.      }
  8.     }
  9.     return null;
  10.    })
  11.    .toSingle();
  12. }

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

  1. Single<Post> findById(Long id) {
  2.   return this.db.select("select * from posts where id=?")
  3.     .parameter(id)
  4.     .get(
  5.       rs -> new Post(rs.getLong("id"),
  6.         rs.getString("title"),
  7.         rs.getString("content")
  8.       )
  9.     )
  10.     .first()
  11.     .toSingle();
  12. }

代码示例来源：origin: bravekingzhang/CleanArch

  1. @Override
  2.   public Observable<List<SampleModel>> lists(int count, int page) {
  3.     Realm realm = Realm.getDefaultInstance();
  4.     Observable observable = realm.where(SampleModel.class).findAll().asObservable().map(new Func1<RealmResults<SampleModel>, List<SampleModel>>() {
  5.       @Override
  6.       public List<SampleModel> call(RealmResults<SampleModel> sampleModels) {
  7.         return Converter.RealmResultList2SampleModel(sampleModels);
  8.       }
  9.     });
  10.     return observable.first();
  11.   }
  12. //realm maybe have some bugs....,fuck

代码示例来源：origin: ArturVasilov/AndroidSchool

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

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

  1. @Override public Completable removeDownload(String md5) {
  2.  return downloadsRepository.getDownload(md5)
  3.    .first()
  4.    .flatMap(download -> getAppDownloader(download.getMd5()).flatMap(
  5.      appDownloader -> appDownloader.removeAppDownload()
  6.        .andThen(downloadsRepository.remove(md5))
  7.        .andThen(Observable.just(download))))
  8.    .doOnNext(download -> removeDownloadFiles(download))
  9.    .toCompletable();
  10. }

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

  1. @Override public Completable pauseDownload(String md5) {
  2.  return downloadsRepository.getDownload(md5)
  3.    .first()
  4.    .map(download -> {
  5.     download.setOverallDownloadStatus(Download.PAUSED);
  6.     downloadsRepository.save(download);
  7.     return download;
  8.    })
  9.    .flatMap(download -> getAppDownloader(download.getMd5()))
  10.    .flatMapCompletable(appDownloader -> appDownloader.pauseAppDownload())
  11.    .toCompletable();
  12. }

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

  1. @Test
  2. public void sample_161() throws Exception {
  3.   Observable<Person> person = Observable.just(new Person());
  4.   Observable<Income> income = person
  5.       .flatMap(this::determineIncome)
  6.       .flatMap(
  7.           Observable::just,
  8.           th -> Observable.empty(),
  9.           Observable::empty)
  10.       .concatWith(person.flatMap(this::guessIncome))
  11.       .first();
  12. }

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

  1. private Observable<Download> handleDownloadProgress(AppDownloader appDownloader) {
  2.  return appDownloader.observeDownloadProgress()
  3.    .flatMap(appDownloadStatus -> downloadsRepository.getDownload(appDownloadStatus.getMd5())
  4.      .first()
  5.      .flatMap(download -> updateDownload(download, appDownloadStatus)))
  6.    .filter(download -> download.getOverallDownloadStatus() == Download.COMPLETED)
  7.    .doOnNext(download -> removeAppDownloader(download.getMd5()))
  8.    .doOnNext(download -> downloadAnalytics.onDownloadComplete(download.getMd5(),
  9.      download.getPackageName(), download.getVersionCode()))
  10.    .takeUntil(download -> download.getOverallDownloadStatus() == Download.COMPLETED);
  11. }

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

  1. @Test
  2. public void sample_570() throws Exception {
  3.   Observable<Car> fromCache = loadFromCache();
  4.   Observable<Car> fromDb = loadFromDb();
  5.   Observable<Car> found = Observable
  6.       .concat(fromCache, fromDb)
  7.       .first();
  8. }

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