rx.subjects.PublishSubject 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.subjects;
import java.util.*;
import rx.Observer;
import rx.annotations.Beta;
import rx.exceptions.Exceptions;
import rx.functions.Action1;
import rx.internal.operators.NotificationLite;
import rx.subjects.SubjectSubscriptionManager.SubjectObserver;
/**
* Subject that, once an {@link Observer} has subscribed, emits all subsequently observed items to the
* subscriber.
*
* 
*
* Example usage:
*
*
{@code
PublishSubject
*
* @param
* the type of items observed and emitted by the Subject
*/
public final class PublishSubject extends Subject {
/**
* Creates and returns a new {@code PublishSubject}.
*
* @param the value type
* @return the new {@code PublishSubject}
*/
public static PublishSubject create() {
final SubjectSubscriptionManager state = new SubjectSubscriptionManager();
state.onTerminated = new Action1>() {
@Override
public void call(SubjectObserver o) {
o.emitFirst(state.getLatest(), state.nl);
}
};
return new PublishSubject(state, state);
}
final SubjectSubscriptionManager state;
private final NotificationLite nl = NotificationLite.instance();
protected PublishSubject(OnSubscribe onSubscribe, SubjectSubscriptionManager state) {
super(onSubscribe);
this.state = state;
}
@Override
public void onCompleted() {
if (state.active) {
Object n = nl.completed();
for (SubjectObserver bo : state.terminate(n)) {
bo.emitNext(n, state.nl);
}
}
}
@Override
public void onError(final Throwable e) {
if (state.active) {
Object n = nl.error(e);
List errors = null;
for (SubjectObserver bo : state.terminate(n)) {
try {
bo.emitNext(n, state.nl);
} catch (Throwable e2) {
if (errors == null) {
errors = new ArrayList();
}
errors.add(e2);
}
}
Exceptions.throwIfAny(errors);
}
}
@Override
public void onNext(T v) {
for (SubjectObserver bo : state.observers()) {
bo.onNext(v);
}
}
@Override
public boolean hasObservers() {
return state.observers().length > 0;
}
/**
* Check if the Subject has terminated with an exception.
* @return true if the subject has received a throwable through {@code onError}.
*/
@Beta
public boolean hasThrowable() {
Object o = state.getLatest();
return nl.isError(o);
}
/**
* Check if the Subject has terminated normally.
* @return true if the subject completed normally via {@code onCompleted}
*/
@Beta
public boolean hasCompleted() {
Object o = state.getLatest();
return o != null && !nl.isError(o);
}
/**
* Returns the Throwable that terminated the Subject.
* @return the Throwable that terminated the Subject or {@code null} if the
* subject hasn't terminated yet or it terminated normally.
*/
@Beta
public Throwable getThrowable() {
Object o = state.getLatest();
if (nl.isError(o)) {
return nl.getError(o);
}
return null;
}
}