问题
I have read Android documentation in which a piece of code is synchronized inside the onCreate method, Sync Adapter. AFAIK Android only creates one instance of a Service so, can Android call onCreate from different threads at the same time? or is it possible to call a Service method before onCreate has finished (using AIDL)?
回答1:
The documentation you linked to (regarding creating SyncAdapter in a thread-safe manner) makes no sense. onCreate() of a Service is only ever called on the main thread, so there is no possibility that this isn't thread-safe.
Also, you cannot call any methods using AIDL before the onCreate() completes, because you would first need to bind to the Service, and you can't bind to the Service until onCreate() completes.
来源：https://stackoverflow.com/questions/29926361/calling-oncreate-from-different-threads-at-the-same-time