rx.subjects

Class BehaviorSubject<T>

java.lang.Object

rx.Observable<R>

rx.subjects.Subject<T,T>

rx.subjects.BehaviorSubject<T>

Type Parameters:

T - the type of item expected to be observed by the Subject

All Implemented Interfaces:

Observer<T>

public final class BehaviorSubject<T>
extends Subject<T,T>

Subject that emits the most recent item it has observed and all subsequent observed items to each subscribed Observer.

Example usage:

 

  // observer will receive all 4 events (including "default").
  BehaviorSubject<Object> subject = BehaviorSubject.create("default");
  subject.subscribe(observer);
  subject.onNext("one");
  subject.onNext("two");
  subject.onNext("three");

  // observer will receive the "one", "two" and "three" events, but not "default" and "zero"
  BehaviorSubject<Object> subject = BehaviorSubject.create("default");
  subject.onNext("zero");
  subject.onNext("one");
  subject.subscribe(observer);
  subject.onNext("two");
  subject.onNext("three");

  // observer will receive only onCompleted
  BehaviorSubject<Object> subject = BehaviorSubject.create("default");
  subject.onNext("zero");
  subject.onNext("one");
  subject.onCompleted();
  subject.subscribe(observer);

  // observer will receive only onError
  BehaviorSubject<Object> subject = BehaviorSubject.create("default");
  subject.onNext("zero");
  subject.onNext("one");
  subject.onError(new RuntimeException("error"));
  subject.subscribe(observer);
   

Nested Class Summary

Nested classes/interfaces inherited from class rx.Observable

Observable.OnSubscribe<T>, Observable.Operator<R,T>, Observable.Transformer<T,R>

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BehaviorSubject(Observable.OnSubscribe<T> onSubscribe, rx.subjects.SubjectSubscriptionManager<T> state)

Method Summary

Modifier and Type	Method and Description
static <T> BehaviorSubject<T>	create() Creates a BehaviorSubject without a default item.
static <T> BehaviorSubject<T>	create(T defaultValue) Creates a BehaviorSubject that emits the last item it observed and all subsequent items to each Observer that subscribes to it.
java.lang.Throwable	getThrowable() Returns the Throwable that terminated the Subject.
T	getValue() Returns the current value of the Subject if there is such a value and the subject hasn't terminated yet.
java.lang.Object[]	getValues() Returns a snapshot of the currently buffered non-terminal events.
T[]	getValues(T[] a) Returns a snapshot of the currently buffered non-terminal events into the provided a array or creates a new array if it has not enough capacity.
boolean	hasCompleted() Check if the Subject has terminated normally.
boolean	hasObservers() Indicates whether the Subject has Observers subscribed to it.
boolean	hasThrowable() Check if the Subject has terminated with an exception.
boolean	hasValue() Check if the Subject has a value.
void	onCompleted() Notifies the Observer that the Observable has finished sending push-based notifications.
void	onError(java.lang.Throwable e) Notifies the Observer that the Observable has experienced an error condition.
void	onNext(T v) Provides the Observer with a new item to observe.

Methods inherited from class rx.subjects.Subject

toSerialized

Methods inherited from class rx.Observable

all, amb, amb, amb, amb, amb, amb, amb, amb, amb, ambWith, asObservable, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, cache, cache, cacheWithInitialCapacity, cast, collect, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatestDelayError, compose, concat, concat, concat, concat, concat, concat, concat, concat, concat, concat, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatEager, concatMap, concatMapDelayError, concatMapEager, concatMapEager, concatMapEager, concatMapIterable, concatWith, contains, count, countLong, create, debounce, debounce, debounce, defaultIfEmpty, defer, delay, delay, delay, delay, delaySubscription, delaySubscription, delaySubscription, delaySubscription, dematerialize, distinct, distinct, distinctUntilChanged, distinctUntilChanged, distinctUntilChanged, doAfterTerminate, doOnCompleted, doOnEach, doOnEach, doOnError, doOnNext, doOnRequest, doOnSubscribe, doOnTerminate, doOnUnsubscribe, elementAt, elementAtOrDefault, empty, error, exists, filter, finallyDo, first, first, firstOrDefault, firstOrDefault, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMapCompletable, flatMapCompletable, flatMapCompletable, flatMapIterable, flatMapIterable, flatMapIterable, flatMapIterable, flatMapSingle, flatMapSingle, flatMapSingle, forEach, forEach, forEach, from, from, from, from, from, fromCallable, groupBy, groupBy, groupBy, groupBy, groupJoin, ignoreElements, interval, interval, interval, interval, isEmpty, join, just, just, just, just, just, just, just, just, just, just, last, last, lastOrDefault, lastOrDefault, lift, limit, map, materialize, merge, merge, merge, merge, merge, merge, merge, merge, merge, merge, merge, merge, merge, merge, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeWith, nest, never, observeOn, observeOn, observeOn, observeOn, ofType, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureDrop, onBackpressureDrop, onBackpressureLatest, onErrorResumeNext, onErrorResumeNext, onErrorReturn, onExceptionResumeNext, onTerminateDetach, publish, publish, range, range, rebatchRequests, reduce, reduce, repeat, repeat, repeat, repeat, repeatWhen, repeatWhen, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, retry, retry, retry, retryWhen, retryWhen, sample, sample, sample, scan, scan, sequenceEqual, sequenceEqual, serialize, share, single, single, singleOrDefault, singleOrDefault, skip, skip, skip, skipLast, skipLast, skipLast, skipUntil, skipWhile, sorted, sorted, startWith, startWith, startWith, startWith, startWith, startWith, startWith, startWith, startWith, startWith, startWith, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribeOn, subscribeOn, switchIfEmpty, switchMap, switchMapDelayError, switchOnNext, switchOnNextDelayError, take, take, take, takeFirst, takeLast, takeLast, takeLast, takeLast, takeLast, takeLastBuffer, takeLastBuffer, takeLastBuffer, takeLastBuffer, takeLastBuffer, takeUntil, takeUntil, takeWhile, test, test, throttleFirst, throttleFirst, throttleLast, throttleLast, throttleWithTimeout, throttleWithTimeout, timeInterval, timeInterval, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timer, timer, timer, timer, timestamp, timestamp, to, toBlocking, toCompletable, toList, toMap, toMap, toMap, toMultimap, toMultimap, toMultimap, toMultimap, toSingle, toSortedList, toSortedList, toSortedList, toSortedList, unsafeCreate, unsafeSubscribe, unsubscribeOn, using, using, window, window, window, window, window, window, window, window, window, window, window, window, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zipWith, zipWith

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BehaviorSubject

protected BehaviorSubject(Observable.OnSubscribe<T> onSubscribe,
                          rx.subjects.SubjectSubscriptionManager<T> state)

Method Detail

create

public static <T> BehaviorSubject<T> create()

Creates a BehaviorSubject without a default item.

Type Parameters:

T - the type of item the Subject will emit

Returns:

the constructed BehaviorSubject

create

public static <T> BehaviorSubject<T> create(T defaultValue)

Creates a BehaviorSubject that emits the last item it observed and all subsequent items to each Observer that subscribes to it.

Type Parameters:

T - the type of item the Subject will emit

Parameters:

defaultValue - the item that will be emitted first to any Observer as long as the BehaviorSubject has not yet observed any items from its source Observable

Returns:

the constructed BehaviorSubject

onCompleted

public void onCompleted()

Description copied from interface: Observer

Notifies the Observer that the Observable has finished sending push-based notifications.

The Observable will not call this method if it calls Observer.onError(java.lang.Throwable).

onError

public void onError(java.lang.Throwable e)

Description copied from interface: Observer

Notifies the Observer that the Observable has experienced an error condition.

If the Observable calls this method, it will not thereafter call Observer.onNext(T) or Observer.onCompleted().

Parameters:

e - the exception encountered by the Observable

onNext

public void onNext(T v)

Description copied from interface: Observer

Provides the Observer with a new item to observe.

The Observable may call this method 0 or more times.

The Observable will not call this method again after it calls either Observer.onCompleted() or Observer.onError(java.lang.Throwable).

Parameters:

v - the item emitted by the Observable

hasObservers

public boolean hasObservers()

Description copied from class: Subject

Indicates whether the Subject has Observers subscribed to it.

Specified by:

hasObservers in class Subject<T,T>

Returns:

true if there is at least one Observer subscribed to this Subject, false otherwise

hasValue

public boolean hasValue()

Check if the Subject has a value.

Use the getValue() method to retrieve such a value.

Note that unless hasCompleted() or hasThrowable() returns true, the value retrieved by getValue() may get outdated.

Returns:

true if and only if the subject has some value and hasn't terminated yet.

Since:

1.2

hasThrowable

public boolean hasThrowable()

Check if the Subject has terminated with an exception.

Returns:

true if the subject has received a throwable through onError.

Since:

1.2

hasCompleted

public boolean hasCompleted()

Check if the Subject has terminated normally.

Returns:

true if the subject completed normally via onCompleted()

Since:

1.2

getValue

public T getValue()

Returns the current value of the Subject if there is such a value and the subject hasn't terminated yet.

The method can return null for various reasons. Use hasValue(), hasThrowable() and hasCompleted() to determine if such null is a valid value, there was an exception or the Subject terminated (with or without receiving any value).

Returns:

the current value or null if the Subject doesn't have a value, has terminated or has an actual null as a valid value.

Since:

1.2

getThrowable

public java.lang.Throwable getThrowable()

Returns the Throwable that terminated the Subject.

Returns:

the Throwable that terminated the Subject or null if the subject hasn't terminated yet or it terminated normally.

Since:

1.2

getValues

public T[] getValues(T[] a)

Returns a snapshot of the currently buffered non-terminal events into the provided a array or creates a new array if it has not enough capacity.

Parameters:

a - the array to fill in

Returns:

the array a if it had enough capacity or a new array containing the available values

Since:

1.2

getValues

public java.lang.Object[] getValues()

Returns a snapshot of the currently buffered non-terminal events.

The operation is thread-safe.

Returns:

a snapshot of the currently buffered non-terminal events.

Since:

(If this graduates from being an Experimental class method, replace this parenthetical with the release number), 1.2