Learning RxJava

startWith()

For a given Observable<T>, the startWith() operator allows you to insert a T emission that precedes all the other emissions. For instance, if we have an Observable<String>that emits items on a menu we want to print, we can use startWith() to append a title header first:

import io.reactivex.Observable;public class Launcher {      public static void main(String[] args) {        Observable<String> menu =          Observable.just("Coffee", "Tea", "Espresso", "Latte");        //print menu        menu.startWith("COFFEE SHOP MENU")          .subscribe(System.out::println);      }}

The output of the preceding code snippet is as follows:

COFFEE SHOP MENUCoffeeTeaEspressoLatte

If you want to start with more than one emission, use startWithArray() to accept varargs parameters. If we want ...