/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex;
import io.reactivex.annotations.*;
import io.reactivex.disposables.Disposable;
/**
* Provides a mechanism for receiving push-based notifications.
* <p>
* After a SingleObserver calls a {@link Single}'s {@link Single#subscribe subscribe} method,
* first the Single calls {@link #onSubscribe(Disposable)} with a {@link Disposable} that allows
* cancelling the sequence at any time, then the
* {@code Single} calls only one of the SingleObserver {@link #onSuccess} and {@link #onError} methods to provide
* notifications.
*
* @see <a href="http://reactivex.io/documentation/observable.html">ReactiveX documentation: Observable</a>
* @param <T>
* the type of item the SingleObserver expects to observe
* @since 2.0
*/
public interface SingleObserver<T> {
/**
* Provides the SingleObserver with the means of cancelling (disposing) the
* connection (channel) with the Single in both
* synchronous (from within {@code onSubscribe(Disposable)} itself) and asynchronous manner.
* @param d the Disposable instance whose {@link Disposable#dispose()} can
* be called anytime to cancel the connection
* @since 2.0
*/
void onSubscribe(@NonNull Disposable d);
/**
* Notifies the SingleObserver with a single item and that the {@link Single} has finished sending
* push-based notifications.
* <p>
* The {@link Single} will not call this method if it calls {@link #onError}.
*
* @param t
* the item emitted by the Single
*/
void onSuccess(@NonNull T t);
/**
* Notifies the SingleObserver that the {@link Single} has experienced an error condition.
* <p>
* If the {@link Single} calls this method, it will not thereafter call {@link #onSuccess}.
*
* @param e
* the exception encountered by the Single
*/
void onError(@NonNull Throwable e);
}