출처 : brunch.co.kr/@lonnie/18 jungwoon.github.io/rxjava2/2019/07/05/RxJava-1/ www.vogella.com/tutorials/RxJava/article.html : 많은 예시와 how to Observable source = Observable.create(subscriber -> { try { if (!subscriber.isUnsubscribed()) { for (int i = 1; i Syste..