rx.observables

Class BlockingObservable<T>

java.lang.Object

rx.observables.BlockingObservable<T>

Type Parameters:

T - the type of item emitted by the BlockingObservable

public final class BlockingObservable<T>
extends java.lang.Object

BlockingObservable is a variety of Observable that provides blocking operators. It can be useful for testing and demo purposes, but is generally inappropriate for production applications (if you think you need to use a BlockingObservable this is usually a sign that you should rethink your design).

You construct a BlockingObservable from an Observable with from(Observable) or Observable.toBlocking().

The documentation for this interface makes use of a form of marble diagram that has been modified to illustrate blocking operators. The following legend explains these marble diagrams:

See Also:

RxJava wiki: Blocking Observable Operators

Method Summary

Modifier and Type	Method and Description
T	first() Returns the first item emitted by this BlockingObservable, or throws NoSuchElementException if it emits no items.
T	first(Func1<? super T,java.lang.Boolean> predicate) Returns the first item emitted by this BlockingObservable that matches a predicate, or throws NoSuchElementException if it emits no such item.
T	firstOrDefault(T defaultValue) Returns the first item emitted by this BlockingObservable, or a default value if it emits no items.
T	firstOrDefault(T defaultValue, Func1<? super T,java.lang.Boolean> predicate) Returns the first item emitted by this BlockingObservable that matches a predicate, or a default value if it emits no such items.
void	forEach(Action1<? super T> onNext) Invokes a method on each item emitted by this BlockingObservable and blocks until the Observable completes.
static <T> BlockingObservable<T>	from(Observable<? extends T> o) Converts an Observable into a BlockingObservable.
java.util.Iterator<T>	getIterator() Returns an Iterator that iterates over all items emitted by this BlockingObservable.
T	last() Returns the last item emitted by this BlockingObservable, or throws NoSuchElementException if this BlockingObservable emits no items.
T	last(Func1<? super T,java.lang.Boolean> predicate) Returns the last item emitted by this BlockingObservable that matches a predicate, or throws NoSuchElementException if it emits no such items.
T	lastOrDefault(T defaultValue) Returns the last item emitted by this BlockingObservable, or a default value if it emits no items.
T	lastOrDefault(T defaultValue, Func1<? super T,java.lang.Boolean> predicate) Returns the last item emitted by this BlockingObservable that matches a predicate, or a default value if it emits no such items.
java.lang.Iterable<T>	latest() Returns an Iterable that returns the latest item emitted by this BlockingObservable, waiting if necessary for one to become available.
java.lang.Iterable<T>	mostRecent(T initialValue) Returns an Iterable that always returns the item most recently emitted by this BlockingObservable.
java.lang.Iterable<T>	next() Returns an Iterable that blocks until this BlockingObservable emits another item, then returns that item.
T	single() If this BlockingObservable completes after emitting a single item, return that item, otherwise throw a NoSuchElementException.
T	single(Func1<? super T,java.lang.Boolean> predicate) If this BlockingObservable completes after emitting a single item that matches a given predicate, return that item, otherwise throw a NoSuchElementException.
T	singleOrDefault(T defaultValue) If this BlockingObservable completes after emitting a single item, return that item; if it emits more than one item, throw an IllegalArgumentException; if it emits no items, return a default value.
T	singleOrDefault(T defaultValue, Func1<? super T,java.lang.Boolean> predicate) If this BlockingObservable completes after emitting a single item that matches a predicate, return that item; if it emits more than one such item, throw an IllegalArgumentException; if it emits no items, return a default value.
void	subscribe() Runs the source observable to a terminal event, ignoring any values and rethrowing any exception.
void	subscribe(Action1<? super T> onNext) Subscribes to the source and calls the given action on the current thread and rethrows any exception wrapped into OnErrorNotImplementedException.
void	subscribe(Action1<? super T> onNext, Action1<? super java.lang.Throwable> onError) Subscribes to the source and calls the given actions on the current thread.
void	subscribe(Action1<? super T> onNext, Action1<? super java.lang.Throwable> onError, Action0 onCompleted) Subscribes to the source and calls the given actions on the current thread.
void	subscribe(Observer<? super T> observer) Subscribes to the source and calls back the Observer methods on the current thread.
void	subscribe(Subscriber<? super T> subscriber) Subscribes to the source and calls the Subscriber methods on the current thread.
java.util.concurrent.Future<T>	toFuture() Returns a Future representing the single value emitted by this BlockingObservable.
java.lang.Iterable<T>	toIterable() Converts this BlockingObservable into an Iterable.

Methods inherited from class java.lang.Object

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

Method Detail

from

public static <T> BlockingObservable<T> from(Observable<? extends T> o)

Converts an Observable into a BlockingObservable.

Type Parameters:

T - the observed value type

Parameters:

o - the Observable you want to convert

Returns:

a BlockingObservable version of o

forEach

public void forEach(Action1<? super T> onNext)

Invokes a method on each item emitted by this BlockingObservable and blocks until the Observable completes.

Note: This will block even if the underlying Observable is asynchronous.

This is similar to Observable.subscribe(Subscriber), but it blocks. Because it blocks it does not need the Observer.onCompleted() or Observer.onError(Throwable) methods. If the underlying Observable terminates with an error, rather than calling onError, this method will throw an exception.

The difference between this method and subscribe(Action1) is that the onNext action is executed on the emission thread instead of the current thread.

Parameters:

onNext - the Action1 to invoke for each item emitted by the BlockingObservable

Throws:

java.lang.RuntimeException - if an error occurs

See Also:

ReactiveX documentation: Subscribe, subscribe(Action1)

getIterator

public java.util.Iterator<T> getIterator()

Returns an Iterator that iterates over all items emitted by this BlockingObservable.

Returns:

an Iterator that can iterate over the items emitted by this BlockingObservable

See Also:

ReactiveX documentation: To

first

public T first()

Returns the first item emitted by this BlockingObservable, or throws NoSuchElementException if it emits no items.

Returns:

the first item emitted by this BlockingObservable

Throws:

java.util.NoSuchElementException - if this BlockingObservable emits no items

See Also:

ReactiveX documentation: First

first

public T first(Func1<? super T,java.lang.Boolean> predicate)

Returns the first item emitted by this BlockingObservable that matches a predicate, or throws NoSuchElementException if it emits no such item.

Parameters:

predicate - a predicate function to evaluate items emitted by this BlockingObservable

Returns:

the first item emitted by this BlockingObservable that matches the predicate

Throws:

java.util.NoSuchElementException - if this BlockingObservable emits no such items

See Also:

ReactiveX documentation: First

firstOrDefault

public T firstOrDefault(T defaultValue)

Returns the first item emitted by this BlockingObservable, or a default value if it emits no items.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no items

Returns:

the first item emitted by this BlockingObservable, or the default value if it emits no items

See Also:

ReactiveX documentation: First

firstOrDefault

public T firstOrDefault(T defaultValue,
                        Func1<? super T,java.lang.Boolean> predicate)

Returns the first item emitted by this BlockingObservable that matches a predicate, or a default value if it emits no such items.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no matching items

predicate - a predicate function to evaluate items emitted by this BlockingObservable

Returns:

the first item emitted by this BlockingObservable that matches the predicate, or the default value if this BlockingObservable emits no matching items

See Also:

ReactiveX documentation: First

last

public T last()

Returns the last item emitted by this BlockingObservable, or throws NoSuchElementException if this BlockingObservable emits no items.

Returns:

the last item emitted by this BlockingObservable

Throws:

java.util.NoSuchElementException - if this BlockingObservable emits no items

See Also:

ReactiveX documentation: Last

last

public T last(Func1<? super T,java.lang.Boolean> predicate)

Returns the last item emitted by this BlockingObservable that matches a predicate, or throws NoSuchElementException if it emits no such items.

Parameters:

predicate - a predicate function to evaluate items emitted by the BlockingObservable

Returns:

the last item emitted by the BlockingObservable that matches the predicate

Throws:

java.util.NoSuchElementException - if this BlockingObservable emits no items

See Also:

ReactiveX documentation: Last

lastOrDefault

public T lastOrDefault(T defaultValue)

Returns the last item emitted by this BlockingObservable, or a default value if it emits no items.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no items

Returns:

the last item emitted by the BlockingObservable, or the default value if it emits no items

See Also:

ReactiveX documentation: Last

lastOrDefault

public T lastOrDefault(T defaultValue,
                       Func1<? super T,java.lang.Boolean> predicate)

Returns the last item emitted by this BlockingObservable that matches a predicate, or a default value if it emits no such items.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no matching items

predicate - a predicate function to evaluate items emitted by this BlockingObservable

Returns:

the last item emitted by this BlockingObservable that matches the predicate, or the default value if it emits no matching items

See Also:

ReactiveX documentation: Last

mostRecent

public java.lang.Iterable<T> mostRecent(T initialValue)

Returns an Iterable that always returns the item most recently emitted by this BlockingObservable.

Parameters:

initialValue - the initial value that the Iterable sequence will yield if this BlockingObservable has not yet emitted an item

Returns:

an Iterable that on each iteration returns the item that this BlockingObservable has most recently emitted

See Also:

ReactiveX documentation: First

next

public java.lang.Iterable<T> next()

Returns an Iterable that blocks until this BlockingObservable emits another item, then returns that item.

Returns:

an Iterable that blocks upon each iteration until this BlockingObservable emits a new item, whereupon the Iterable returns that item

See Also:

ReactiveX documentation: TakeLast

latest

public java.lang.Iterable<T> latest()

Returns an Iterable that returns the latest item emitted by this BlockingObservable, waiting if necessary for one to become available.

If this BlockingObservable produces items faster than Iterator.next takes them, onNext events might be skipped, but onError or onCompleted events are not.

Note also that an onNext directly followed by onCompleted might hide the onNext event.

Returns:

an Iterable that always returns the latest item emitted by this BlockingObservable

See Also:

ReactiveX documentation: First

single

public T single()

If this BlockingObservable completes after emitting a single item, return that item, otherwise throw a NoSuchElementException.

Returns:

the single item emitted by this BlockingObservable

See Also:

ReactiveX documentation: First

single

public T single(Func1<? super T,java.lang.Boolean> predicate)

If this BlockingObservable completes after emitting a single item that matches a given predicate, return that item, otherwise throw a NoSuchElementException.

Parameters:

predicate - a predicate function to evaluate items emitted by this BlockingObservable

Returns:

the single item emitted by this BlockingObservable that matches the predicate

See Also:

ReactiveX documentation: First

singleOrDefault

public T singleOrDefault(T defaultValue)

If this BlockingObservable completes after emitting a single item, return that item; if it emits more than one item, throw an IllegalArgumentException; if it emits no items, return a default value.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no items

Returns:

the single item emitted by this BlockingObservable, or the default value if it emits no items

See Also:

ReactiveX documentation: First

singleOrDefault

public T singleOrDefault(T defaultValue,
                         Func1<? super T,java.lang.Boolean> predicate)

If this BlockingObservable completes after emitting a single item that matches a predicate, return that item; if it emits more than one such item, throw an IllegalArgumentException; if it emits no items, return a default value.

Parameters:

defaultValue - a default value to return if this BlockingObservable emits no matching items

predicate - a predicate function to evaluate items emitted by this BlockingObservable

Returns:

the single item emitted by the BlockingObservable that matches the predicate, or the default value if no such items are emitted

See Also:

ReactiveX documentation: First

toFuture

public java.util.concurrent.Future<T> toFuture()

Returns a Future representing the single value emitted by this BlockingObservable.

If BlockingObservable emits more than one item, Future will receive an IllegalArgumentException. If BlockingObservable is empty, Future will receive an NoSuchElementException.

If the BlockingObservable may emit more than one item, use Observable.toList().toBlocking().toFuture().

Returns:

a Future that expects a single item to be emitted by this BlockingObservable

See Also:

ReactiveX documentation: To

toIterable

public java.lang.Iterable<T> toIterable()

Converts this BlockingObservable into an Iterable.

Returns:

an Iterable version of this BlockingObservable

See Also:

ReactiveX documentation: To

subscribe

public void subscribe()

Runs the source observable to a terminal event, ignoring any values and rethrowing any exception.

Since:

1.3

subscribe

public void subscribe(Observer<? super T> observer)

Subscribes to the source and calls back the Observer methods on the current thread.

Parameters:

observer - the observer to call event methods on

Since:

1.3

subscribe

public void subscribe(Subscriber<? super T> subscriber)

Subscribes to the source and calls the Subscriber methods on the current thread.

The unsubscription and backpressure is composed through.

Parameters:

subscriber - the subscriber to forward events and calls to in the current thread

Since:

1.3

subscribe

public void subscribe(Action1<? super T> onNext)

Subscribes to the source and calls the given action on the current thread and rethrows any exception wrapped into OnErrorNotImplementedException.

The difference between this method and forEach(Action1) is that the action is always executed on the current thread.

Parameters:

onNext - the callback action for each source value

Since:

1.3

See Also:

forEach(Action1)

subscribe

public void subscribe(Action1<? super T> onNext,
                      Action1<? super java.lang.Throwable> onError)

Subscribes to the source and calls the given actions on the current thread.

Parameters:

onNext - the callback action for each source value

onError - the callback action for an error event

Since:

1.3

subscribe

public void subscribe(Action1<? super T> onNext,
                      Action1<? super java.lang.Throwable> onError,
                      Action0 onCompleted)

Subscribes to the source and calls the given actions on the current thread.

Parameters:

onNext - the callback action for each source value

onError - the callback action for an error event

onCompleted - the callback action for the completion event.

Since:

1.3