question: @ MainThread public final void register ( StorageAccessListener storageAccessListener ) { if ( CHECK_THREADS ) { UiThreadContext . assertUiThread ( ) ; } if ( listeners . contains ( storageAccessListener ) ) { throw new StorageAccessException ( "Listener already registered" ) ; } listeners . add ( storageAccessListener ) ; }
target:  Registers a listener. If you want to read/write data, you'll need to implement this to know when file access is ready.