rx.observers.Subscribers Maven / Gradle / Ivy
/**
* Copyright 2014 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rx.observers;
import rx.*;
import rx.exceptions.OnErrorNotImplementedException;
import rx.functions.*;
/**
* Helper methods and utilities for creating and working with {@link Subscriber} objects.
*/
public final class Subscribers {
private Subscribers() {
throw new IllegalStateException("No instances!");
}
/**
* Returns an inert {@link Subscriber} that does nothing in response to the emissions or notifications from
* any {@code Observable} it subscribes to. This is different, however, from an {@code EmptyObserver}, in
* that it will throw an exception if its {@link Subscriber#onError onError} method is called (whereas
* {@code EmptyObserver} will swallow the error in such a case).
*
* @return an inert {@code Observer}
*/
public static Subscriber empty() {
return from(Observers.empty());
}
/**
* Converts an {@link Observer} into a {@link Subscriber}.
*
* @param o
* the {@link Observer} to convert
* @return a {@link Subscriber} version of {@code o}
*/
public static Subscriber from(final Observer o) {
return new Subscriber() {
@Override
public void onCompleted() {
o.onCompleted();
}
@Override
public void onError(Throwable e) {
o.onError(e);
}
@Override
public void onNext(T t) {
o.onNext(t);
}
};
}
/**
* Creates a {@link Subscriber} that receives the emissions of any {@code Observable} it subscribes to via
* {@link Subscriber#onNext onNext} but ignores {@link Subscriber#onError onError} and
* {@link Subscriber#onCompleted onCompleted} notifications.
*
* @param onNext
* a function that handles each item emitted by an {@code Observable}
* @throws IllegalArgument Exception
* if {@code onNext} is {@code null}
* @return a {@code Subscriber} that calls {@code onNext} for each emitted item from the {@code Observable}
* the {@code Subscriber} subscribes to
*/
public static final Subscriber create(final Action1 onNext) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
return new Subscriber() {
@Override
public final void onCompleted() {
// do nothing
}
@Override
public final void onError(Throwable e) {
throw new OnErrorNotImplementedException(e);
}
@Override
public final void onNext(T args) {
onNext.call(args);
}
};
}
/**
* Creates an {@link Subscriber} that receives the emissions of any {@code Observable} it subscribes to via
* {@link Subscriber#onNext onNext} and handles any {@link Subscriber#onError onError} notification but
* ignores an {@link Subscriber#onCompleted onCompleted} notification.
*
* @param onNext
* a function that handles each item emitted by an {@code Observable}
* @param onError
* a function that handles an error notification if one is sent by an {@code Observable}
* @throws IllegalArgument Exception
* if either {@code onNext} or {@code onError} are {@code null}
* @return an {@code Subscriber} that calls {@code onNext} for each emitted item from the {@code Observable}
* the {@code Subscriber} subscribes to, and calls {@code onError} if the {@code Observable}
* notifies of an error
*/
public static final Subscriber create(final Action1 onNext, final Action1 onError) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
return new Subscriber() {
@Override
public final void onCompleted() {
// do nothing
}
@Override
public final void onError(Throwable e) {
onError.call(e);
}
@Override
public final void onNext(T args) {
onNext.call(args);
}
};
}
/**
* Creates an {@link Subscriber} that receives the emissions of any {@code Observable} it subscribes to via
* {@link Subscriber#onNext onNext} and handles any {@link Subscriber#onError onError} or
* {@link Subscriber#onCompleted onCompleted} notifications.
*
* @param onNext
* a function that handles each item emitted by an {@code Observable}
* @param onError
* a function that handles an error notification if one is sent by an {@code Observable}
* @param onComplete
* a function that handles a sequence complete notification if one is sent by an {@code Observable}
* @throws IllegalArgument Exception
* if either {@code onNext}, {@code onError}, or {@code onComplete} are {@code null}
* @return an {@code Subscriber} that calls {@code onNext} for each emitted item from the {@code Observable}
* the {@code Subscriber} subscribes to, calls {@code onError} if the {@code Observable} notifies
* of an error, and calls {@code onComplete} if the {@code Observable} notifies that the observable
* sequence is complete
*/
public static final Subscriber create(final Action1 onNext, final Action1 onError, final Action0 onComplete) {
if (onNext == null) {
throw new IllegalArgumentException("onNext can not be null");
}
if (onError == null) {
throw new IllegalArgumentException("onError can not be null");
}
if (onComplete == null) {
throw new IllegalArgumentException("onComplete can not be null");
}
return new Subscriber() {
@Override
public final void onCompleted() {
onComplete.call();
}
@Override
public final void onError(Throwable e) {
onError.call(e);
}
@Override
public final void onNext(T args) {
onNext.call(args);
}
};
}
/**
* Returns a new {@link Subscriber} that passes all events to
* subscriber, has backpressure controlled by
* subscriber and uses the subscription list of
* subscriber when {@link Subscriber#add(rx.Subscription)} is
* called.
*
* @param subscriber
* the Subscriber to wrap.
*
* @return a new Subscriber that passes all events to
* subscriber, has backpressure controlled by
* subscriber and uses subscriber to
* manage unsubscription.
* @since 1.1.0
*/
public static Subscriber wrap(final Subscriber subscriber) {
return new Subscriber(subscriber) {
@Override
public void onCompleted() {
subscriber.onCompleted();
}
@Override
public void onError(Throwable e) {
subscriber.onError(e);
}
@Override
public void onNext(T t) {
subscriber.onNext(t);
}
};
}
}