Learning RxJava - Second Edition

contains()

The contains() operator checks whether a specified item (based on the hashCode()/equals() implementation) has been emitted by the source Observable. It returns a Single<Boolean> with true if the specified item was emitted, and false if it was not.

In the following code snippet, we emit the integers 1 through 10000, and we check whether the number 9563 is emitted from it using contains():

import io.reactivex.rxjava3.core.Observable;public class Ch3_28 {    public static void main(String[] args) {        Observable.range(1, 10000)                .contains(9563)                .subscribe(s -> System.out.println("Received: " + s));    }}

The output of the preceding code snippet is as follows:

Received: true

As you have probably guessed, the moment the specified value is found, ...