Android -room persistent library - DAO calls are async, therefore how to get callback?

Question

From what i have read Room doesn’t allow you to issue database queries on the main thread (as can cause delays on the main thread)). so imagine i am trying to

Answer 1

There is a way to turn off async and allow synchronous access.

when building the database you can use :allowMainThreadQueries()

and for in memory use: Room.inMemoryDatabaseBuilder()

Although its not recommended. So in the end i can use a in memory database and main thread access if i wanted super fast access. i guess it depends how big my data is and in this case is very small.

but if you did want to use a callback.... using rxJava here is one i made for a list of countries i wanted to store in a database:

public Observable queryCountryInfoFor(final String isoCode) {
    return Observable.fromCallable(new Callable() {
        @Override
        public CountryModel call() throws Exception {
            return db.countriesDao().getCountry(isoCode);
        }
    }).subscribeOn(Schedulers.io())
       
 .observeOn(AndroidSchedulers.mainThread());

}

you can then easily add a subscriber to this function to get the callback with Rxjava.