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

Observable.defaultIfEmpty介绍

[英]Returns an Observable that emits the items emitted by the source Observable or a specified default item if the source Observable is empty.

Scheduler: defaultIfEmpty does not operate by default on a particular Scheduler.
[中]返回一个Observable，该Observable发出源Observable发出的项，如果源Observable为空，则返回指定的默认项。
调度程序：默认情况下，defaultIfEmpty不会在特定调度程序上运行。

代码示例

代码示例来源：origin: apache/usergrid

  1. private void advance(){
  2.    //map to our old results objects, return a default empty if required
  3.   final Observable<Results>
  4.     observable = buildNewResultsPage( cursor ).map( resultsPage -> createResultsInternal( resultsPage ) ).defaultIfEmpty(
  5.     new Results() );
  6.   if (logger.isTraceEnabled()) {
  7.     logger.trace("Trying to load results page");
  8.   }
  9.   //take the first from our observable
  10.   final Results resultsPage = observable.take(1).toBlocking().first();
  11.   if (logger.isTraceEnabled()) {
  12.     logger.trace("Results page loaded {}", resultsPage);
  13.   }
  14.   //set the results for the iterator
  15.   this.results = resultsPage;
  16.   //set the complete flag
  17.   this.complete =  !resultsPage.hasCursor();
  18.   //if not comlete, set our cursor for the next iteration
  19.   if(!complete){
  20.     this.cursor = Optional.of( results.getCursor());
  21.   }else{
  22.     this.cursor = Optional.absent();
  23.   }
  24. }

代码示例来源：origin: ReactiveX/RxNetty

  1. @Override
  2.   public Void call() throws Exception {
  3.     PooledConnection<String, String> connection =
  4.         preferCurrentELHolderRule.holder.pollThisEventLoopConnections()
  5.                         .defaultIfEmpty(null)
  6.                         .toBlocking().single();
  7.     assertThat("Connection available in the eventloop.", connection, is(connection1));
  8.     return null;
  9.   }
  10. }).get(1, TimeUnit.MINUTES);

代码示例来源：origin: ReactiveX/RxNetty

  1. @Override
  2.   public Void call() throws Exception {
  3.     PooledConnection<String, String> connection = preferCurrentELHolderRule.holder.poll()
  4.                                            .defaultIfEmpty(null)
  5.                                            .toBlocking()
  6.                                            .single();
  7.     assertThat("Connection available in the eventloop.", connection, is(connection1));
  8.     return null;
  9.   }
  10. }).get(1, TimeUnit.MINUTES);

代码示例来源：origin: ReactiveX/RxNetty

  1. @Test(timeout = 60000)
  2. public void testPeek() throws Exception {
  3.   PooledConnection<String, String> connection1 = preferCurrentELHolderRule.addConnection();
  4.   PooledConnection<String, String> connection = preferCurrentELHolderRule.holder.peek()
  5.                                          .defaultIfEmpty(null)
  6.                                          .toBlocking().single();
  7.   assertThat("Connection not available with peek.", connection, is(connection1));
  8.   connection = preferCurrentELHolderRule.holder.peek().defaultIfEmpty(null)
  9.                          .toBlocking().single();
  10.   assertThat("Connection not available after peek.", connection, not(nullValue()));
  11.   assertThat("Unexpected connection on peek.", connection, is(connection1));
  12. }

代码示例来源：origin: ReactiveX/RxNetty

  1. @Test(timeout = 60000)
  2. public void testPollRemovesItem() throws Exception {
  3.   PooledConnection<String, String> connection1 = preferCurrentELHolderRule.addConnection();
  4.   PooledConnection<String, String> connection = preferCurrentELHolderRule.holder.poll()
  5.                                          .defaultIfEmpty(null)
  6.                                          .toBlocking().single();
  7.   assertThat("Connection not available with poll.", connection, is(connection1));
  8.   connection = preferCurrentELHolderRule.holder.poll()
  9.                          .defaultIfEmpty(null)
  10.                          .toBlocking().single();
  11.   assertThat("Connection available after poll.", connection, is(nullValue()));
  12. }

代码示例来源：origin: ReactiveX/RxNetty

  1. @Test(timeout = 60000)
  2. public void testRemove() throws Exception {
  3.   PooledConnection<String, String> connection1 = preferCurrentELHolderRule.addConnection();
  4.   PooledConnection<String, String> connection = preferCurrentELHolderRule.holder.peek()
  5.                                          .defaultIfEmpty(null)
  6.                                          .toBlocking().single();
  7.   assertThat("Connection not available with peek.", connection, is(connection1));
  8.   preferCurrentELHolderRule.holder.remove(connection1);
  9.   connection = preferCurrentELHolderRule.holder.peek().defaultIfEmpty(null).toBlocking().single();
  10.   assertThat("Connection not removed.", connection, is(nullValue()));
  11. }

代码示例来源：origin: ReactiveX/RxNetty

  1. private PooledConnection<String, String> _testRelease() throws Exception {
  2.   final Connection<String, String> connection = pooledFactoryRule.getAConnection();
  3.   pooledFactoryRule.assertNoIdleConnection();
  4.   /* Close will release */
  5.   pooledFactoryRule.closeAndAwait(connection); /*Throw error or close quietly*/
  6.   PooledConnection<String, String> connIdle =
  7.       pooledFactoryRule.holder.peek().defaultIfEmpty(null).toBlocking().single();
  8.   assertThat("Release did not add to idle.", connIdle, not(nullValue()));
  9.   return connIdle;
  10. }

代码示例来源：origin: ReactiveX/RxNetty

  1. @Test(timeout = 60000)
  2. public void testPollOutOfEventloop() throws Exception {
  3.   PooledConnection<String, String> connection1 = preferCurrentELHolderRule.addConnection();
  4.   PooledConnection<String, String> connection = preferCurrentELHolderRule.holder.poll()
  5.                                          .defaultIfEmpty(null).toBlocking()
  6.                                          .single();
  7.   assertThat("Unexpected connection.", connection, is(connection1));
  8. }

代码示例来源：origin: apache/usergrid

  1. } )
  2. .defaultIfEmpty( 0 );

代码示例来源：origin: apache/usergrid

  1. } ).count().defaultIfEmpty( 0 ).toBlocking().last();

代码示例来源：origin: ribot/ribot-app-android

  1. public void loadVenues() {
  2.   getMvpView().showVenuesProgress(true);
  3.   mSubscriptions.add(Observable.combineLatest(
  4.       getTodayLatestCheckInAtVenue().defaultIfEmpty(null), mDataManager.getVenues(),
  5.       new Func2<CheckIn, List<Venue>, VenuesInfo>() {
  6.         @Override
  7.         public VenuesInfo call(CheckIn checkIn, List<Venue> venues) {
  8.           return new VenuesInfo(checkIn, venues);
  9.         }
  10.       })
  11.       .observeOn(AndroidSchedulers.mainThread())
  12.       .subscribeOn(Schedulers.io())
  13.       .subscribe(new Subscriber<VenuesInfo>() {
  14.         @Override
  15.         public void onCompleted() {
  16.         }
  17.         @Override
  18.         public void onError(Throwable e) {
  19.           Timber.e("Error loading venues " + e);
  20.           getMvpView().showVenuesProgress(false);
  21.         }
  22.         @Override
  23.         public void onNext(VenuesInfo venuesInfo) {
  24.           getMvpView().showVenues(
  25.               venuesInfo.listVenues,
  26.               venuesInfo.getTodayLatestCheckInAtVenueId());
  27.           getMvpView().showVenuesProgress(false);
  28.         }
  29.       }));
  30. }

代码示例来源：origin: henrymorgen/android-advanced-light

  1. private void defaultIfEmpty() {
  2.   Observable.create(new Observable.OnSubscribe<Integer>() {
  3.     @Override
  4.     public void call(Subscriber<? super Integer> subscriber) {
  5.       subscriber.onCompleted();
  6.     }
  7.   }).defaultIfEmpty(3).subscribe(new Action1<Integer>() {
  8.     @Override
  9.     public void call(Integer integer) {
  10.       Log.d(TAG, "defaultIfEmpty:"+integer);
  11.     }
  12.   });
  13. }

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

  1. @Override
  2.  public void run() {
  3.   Observable.<Integer>empty().defaultIfEmpty(3).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: Aptoide/aptoide-client-v8

  1. public <E extends RealmObject> Observable<Long> count(RealmQuery<E> query) {
  2.  return Observable.just(query.count())
  3.    .flatMap(count -> Observable.just(count)
  4.      .unsubscribeOn(RealmSchedulers.getScheduler()))
  5.    .defaultIfEmpty(0L);
  6. }

代码示例来源：origin: org.hawkular.metrics/hawkular-metrics-core-service

  1. @Override
  2. public Observable<Map<String, String>> getMetricTags(MetricId<?> id) {
  3.   return dataAccess.getMetricTags(id)
  4.       .take(1)
  5.       .map(row -> row.getMap(0, String.class, String.class))
  6.       .defaultIfEmpty(new HashMap<>());
  7. }

代码示例来源：origin: hawkular/hawkular-metrics

  1. @Override
  2. public Observable<Map<String, String>> getMetricTags(MetricId<?> id) {
  3.   return dataAccess.getMetricTags(id)
  4.       .take(1)
  5.       .map(row -> row.getMap(0, String.class, String.class))
  6.       .defaultIfEmpty(new HashMap<>());
  7. }

代码示例来源：origin: uk.os.search/search

  1. public Observable<List<SearchResult>> query(String searchTerm) {
  2.   List<Observable<ServerResponse>> responses = queryProviders(searchTerm);
  3.   return Transform.toSearchResults(responses).map(deduplicate()).defaultIfEmpty(new ArrayList<SearchResult>());
  4. }

代码示例来源：origin: uk.os.search/search

  1. public Observable<List<SearchResult>> query(String searchTerm, double lat, double lon) {
  2.   List<Observable<ServerResponse>> responses = queryProviders(searchTerm);
  3.   responses.addAll(queryProviders(lat, lon));
  4.   return Transform.toSearchResults(responses).map(deduplicate()).defaultIfEmpty(new ArrayList<SearchResult>());
  5. }

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

  1. public <E extends RealmObject> Observable<E> findFirst(RealmQuery<E> query) {
  2.  return Observable.just(query.findFirst())
  3.    .filter(realmObject -> realmObject != null)
  4.    .flatMap(realmObject -> realmObject.<E>asObservable().unsubscribeOn(
  5.      RealmSchedulers.getScheduler()))
  6.    .flatMap(realmObject -> copyFromRealm(realmObject))
  7.    .defaultIfEmpty(null);
  8. }

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

  1. public <E extends RealmObject> Observable<List<E>> findAsList(RealmQuery<E> query) {
  2.  return Observable.just(query.findAll())
  3.    .filter(realmObject -> realmObject != null)
  4.    .flatMap(realmObject -> realmObject.<E>asObservable().unsubscribeOn(
  5.      RealmSchedulers.getScheduler()))
  6.    .flatMap(realmObject -> copyFromRealm(realmObject))
  7.    .defaultIfEmpty(null);
  8. }

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