How to concat data from two observables

Question

I have two observables:

 Observable <Profile> profileObservable = briteDatabase.createQuery(UserMapper.Table.NAME, sql, String.valueOf(userId)).mapToOneOrDefault(UserMapper.MAPPER, null);
 Observable <List<Car>> carObservable = briteDatabase.createQuery(CarMapper.Table.NAME, sql, String.valueOf(userId)).mapToOneOrDefault(CarMapper.MAPPER, null);

 public class Profile {
 int id;
 String name; 
 ArrayList<Car> car; 
 ...
 }

 public class Car {
 int id;
 String brand;
 ...
 }

I need to get list of cars from carObservable and put it to profileObservable (put list of car to Profile), inside method like this:

    @Override
public Observable<Profile> getProfile(String userId) {
    String sql = String.format("SELECT %s FROM %s WHERE %s=?", TextUtils.join(",", UserMapper.PROJECTION), UserMapper.Table.NAME, UserMapper.Columns.ID);

    Observable <Profile> profileObservable = briteDatabase.createQuery(UserMapper.Table.NAME, sql, String.valueOf(userId)).mapToOneOrDefault(UserMapper.MAPPER, null);

    Observable <List<Car>> carsObservable = getCars(String userId);

    /*
     Some important method to concat and return Observable <Profile>. I'm only beginner at RxJava( 

   */

}

Answer 1

Did you try the concat operator, I dont know if I understand quite well your use case, but in case you just need to go through the list of car and then profile, just concat one after the other

@Test
public void testContact() {
    Observable.concat(Observable.just("Hello"),
                      Observable.just("reactive"),
                      Observable.just("world"))
            .subscribe(System.out::println);
}

If you want to initiate in the RxJava world take a look here https://github.com/politrons/reactive