I have read the thread below however I did not see AutoCompleteEditText in the list.
Is it not possible to "save" the value of an AutoCompletEditText?
Apparently EditTexts are possible so maybe the AutoComplete too?
The Settingsmanager is a class.
Look at the code and adapt it to understand the AutoCompleteEditText too.
Please note that the statemanager is a class from 2011