I am studying the Cloud Recognition application on Android platform and have a specific question regarding a callback function. In CloudReco.java, the initApplicationNative method is called in the main thread in the onCreate method. Looking at the implementation of this method in CloudReco.cpp, it registers a callback function through "QCAR::registerCallback(&updateCallback);". Digging into the updateCallback object, the function to be called is identified as virtual void QCAR_onUpdate(QCAR::State& state). My question is: when this function is called, does it start a new thread or not? If so, what other functions in CloudReco.cpp also live in this new thread? Thank you for your time.