Concat() operator to hit the cache first - Droidcon 2016

Concatify.java

 
 //Concatify spell
  Observable<List<Lecture>> getLectures() {
      Observable<List<Lecture>> cacheObservable = getLecturesFromCache();
      Observable<List<Lecture>> lecturesFromServer = getLecturesFromServer();
      return cacheObservable.concatWith(lecturesFromServer)
              .take(1);
  }