rx.subscriptions.Subscriptions 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.subscriptions;
import java.util.concurrent.Future;
import rx.Subscription;
import rx.functions.Action0;
/**
* Helper methods and utilities for creating and working with {@link Subscription} objects
*/
public final class Subscriptions {
/**
* A {@link Subscription} that does nothing when its unsubscribe method is called.
*/
private static final Unsubscribed UNSUBSCRIBED = new Unsubscribed();
private Subscriptions() {
throw new IllegalStateException("No instances!");
}
/**
* Returns a {@link Subscription} to which {@code unsubscribe} does nothing except to change
* {@code isUnsubscribed} to {@code true}. It's stateful and {@code isUnsubscribed} indicates if
* {@code unsubscribe} is called, which is different from {@link #unsubscribed()}.
*
*
* Subscription empty = Subscriptions.empty();
* System.out.println(empty.isUnsubscribed()); // false
* empty.unsubscribe();
* System.out.println(empty.isUnsubscribed()); // true
*
*
* @return a {@link Subscription} to which {@code unsubscribe} does nothing except to change
* {@code isUnsubscribed} to {@code true}
*/
public static Subscription empty() {
return BooleanSubscription.create();
}
/**
* Returns a {@link Subscription} to which {@code unsubscribe} does nothing, as it is already unsubscribed.
* Its {@code isUnsubscribed} always returns {@code true}, which is different from {@link #empty()}.
*
*
* Subscription unsubscribed = Subscriptions.unsubscribed();
* System.out.println(unsubscribed.isUnsubscribed()); // true
*
*
* @return a {@link Subscription} to which {@code unsubscribe} does nothing, as it is already unsubscribed
* @since 1.1.0
*/
public static Subscription unsubscribed() {
return UNSUBSCRIBED;
}
/**
* Creates and returns a {@link Subscription} that invokes the given {@link Action0} when unsubscribed.
*
* @param unsubscribe
* Action to invoke on unsubscribe.
* @return {@link Subscription}
*/
public static Subscription create(final Action0 unsubscribe) {
return BooleanSubscription.create(unsubscribe);
}
/**
* Converts a {@link Future} into a {@link Subscription} and cancels it when unsubscribed.
*
* @param f
* the {@link Future} to convert
* @return a {@link Subscription} that wraps {@code f}
*/
public static Subscription from(final Future> f) {
return new FutureSubscription(f);
}
/** Naming classes helps with debugging. */
static final class FutureSubscription implements Subscription {
final Future> f;
public FutureSubscription(Future> f) {
this.f = f;
}
@Override
public void unsubscribe() {
f.cancel(true);
}
@Override
public boolean isUnsubscribed() {
return f.isCancelled();
}
}
/**
* Converts a set of {@link Subscription}s into a {@link CompositeSubscription} that groups the multiple
* Subscriptions together and unsubscribes from all of them together.
*
* @param subscriptions
* the Subscriptions to group together
* @return a {@link CompositeSubscription} representing the {@code subscriptions} set
*/
public static CompositeSubscription from(Subscription... subscriptions) {
return new CompositeSubscription(subscriptions);
}
/** Naming classes helps with debugging. */
static final class Unsubscribed implements Subscription {
@Override
public void unsubscribe() {
// deliberately ignored
}
@Override
public boolean isUnsubscribed() {
return true;
}
}
}
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