T - the type of item the SingleObserver expects to observepublic interface SingleObserver<T>
 After a SingleObserver calls a Single's subscribe method,
 first the Single calls onSubscribe(Disposable) with a Disposable that allows
 cancelling the sequence at any time, then the
 Single calls only one of the SingleObserver onSuccess(T) and onError(java.lang.Throwable) methods to provide
 notifications.
| Modifier and Type | Method and Description | 
|---|---|
| void | onError(java.lang.Throwable e)Notifies the SingleObserver that the  Singlehas experienced an error condition. | 
| void | onSubscribe(Disposable d)Provides the SingleObserver with the means of cancelling (disposing) the
 connection (channel) with the Single in both
 synchronous (from within  onSubscribe(Disposable)itself) and asynchronous manner. | 
| void | onSuccess(T t)Notifies the SingleObserver with a single item and that the  Singlehas finished sending
 push-based notifications. | 
void onSubscribe(@NonNull Disposable d)
onSubscribe(Disposable) itself) and asynchronous manner.d - the Disposable instance whose Disposable.dispose() can
 be called anytime to cancel the connectionvoid onSuccess(@NonNull T t)
Single has finished sending
 push-based notifications.
 
 The Single will not call this method if it calls onError(java.lang.Throwable).
t - the item emitted by the Singlevoid onError(@NonNull java.lang.Throwable e)
Single has experienced an error condition.
 
 If the Single calls this method, it will not thereafter call onSuccess(T).
e - the exception encountered by the Single