title: How to parse iCalendar RRules to create Calendar instances
body: <p>I'm building an app where I want to display all the instances of an event.</p>
  
  <p>What I'm trying to achieve is to generate dates from the iCalendar object that I'm getting from my REST API.
  I'm fairly new to Android and Java development, but from what I've understood it would be best to generate <a href="https://developer.android.com/reference/kotlin/android/icu/util/Calendar" rel="nofollow noreferrer">Java Calendar class</a> instances, so I can work with them later on. </p>
  
  <p>Do I need to use a RRule parser library like <a href="https://github.com/ical4j/ical4j" rel="nofollow noreferrer">ical4j</a> or <a href="https://github.com/mangstadt/biweekly" rel="nofollow noreferrer">biweekly</a> to achieve that or does the Android platform or Java or Kotlin provide a better way?</p>
  
  <pre><code>{
      "_id": "5d5be0929d5dbf00093e3127",
      "userId": "5d3832d6be7eb100076e2883",
      "iCalendar": {
          "frequency": "WEEKLY",
          "tzid": "Europe/Berlin",
          "dtstart": "1566300988998",
          "dtend": null,
          "interval": 1,
          "byDay": "MO"
      }
  }
  </code></pre>