Calendar Provider (System Calendar) Integration into Android App

Integrating Calendar Provider (System Calendar) into Android Applications

The Android system calendar is accessible through CalendarProvider—a standard Content Provider available since API 14. Most applications use one of two scenarios: reading existing events or creating new ones. Both require runtime permissions and proper URI handling.

Permissions

For reading, use READ_CALENDAR; for writing, use WRITE_CALENDAR. Both are dangerous permissions, requested via ActivityCompat.requestPermissions() or ActivityResultContracts.RequestPermission(). Without explicit runtime requests on Android 6+, you get SecurityException.

Reading Events

Events are stored in the CalendarContract.Events table. Query via ContentResolver:

val projection = arrayOf(
    CalendarContract.Events._ID,
    CalendarContract.Events.TITLE,
    CalendarContract.Events.DTSTART,
    CalendarContract.Events.DTEND,
    CalendarContract.Events.CALENDAR_ID
)

val selection = "${CalendarContract.Events.DTSTART} >= ? AND ${CalendarContract.Events.DTEND} <= ?"
val selectionArgs = arrayOf(
    startMillis.toString(),
    endMillis.toString()
)

val cursor = context.contentResolver.query(
    CalendarContract.Events.CONTENT_URI,
    projection,
    selection,
    selectionArgs,
    "${CalendarContract.Events.DTSTART} ASC"
)

cursor?.use {
    while (it.moveToNext()) {
        val title = it.getString(it.getColumnIndexOrThrow(CalendarContract.Events.TITLE))
        val dtStart = it.getLong(it.getColumnIndexOrThrow(CalendarContract.Events.DTSTART))
        // process
    }
}

Important: use getColumnIndexOrThrow() instead of getColumnIndex()—if the column is missing from the projection, it fails immediately with a clear exception rather than ArrayIndexOutOfBoundsException somewhere in business logic.

Creating an Event

val values = ContentValues().apply {
    put(CalendarContract.Events.CALENDAR_ID, calendarId)
    put(CalendarContract.Events.TITLE, "Team Meeting")
    put(CalendarContract.Events.DTSTART, startMillis)
    put(CalendarContract.Events.DTEND, endMillis)
    put(CalendarContract.Events.EVENT_TIMEZONE, TimeZone.getDefault().id)
    put(CalendarContract.Events.DESCRIPTION, "Release v2.1 discussion")
}

val uri = context.contentResolver.insert(CalendarContract.Events.CONTENT_URI, values)
val eventId = uri?.lastPathSegment?.toLong()

EVENT_TIMEZONE is a mandatory field. Without it, the event is created in UTC, and users see incorrect times after a timezone change. This is a classic error that reaches production and manifests in users from other regions.

Adding a Reminder

val reminderValues = ContentValues().apply {
    put(CalendarContract.Reminders.EVENT_ID, eventId)
    put(CalendarContract.Reminders.MINUTES, 15)
    put(CalendarContract.Reminders.METHOD, CalendarContract.Reminders.METHOD_ALERT)
}
context.contentResolver.insert(CalendarContract.Reminders.CONTENT_URI, reminderValues)

Opening System UI

If your app doesn't need direct data access but only wants to open the standard event-creation interface, use Intent without permissions:

val intent = Intent(Intent.ACTION_INSERT).apply {
    data = CalendarContract.Events.CONTENT_URI
    putExtra(CalendarContract.Events.TITLE, "Event Title")
    putExtra(CalendarContract.EXTRA_EVENT_BEGIN_TIME, startMillis)
    putExtra(CalendarContract.EXTRA_EVENT_END_TIME, endMillis)
}
startActivity(intent)

This is simpler, safer, and doesn't require permissions. It suits most cases where the app doesn't maintain its own event list.

Integrating CalendarProvider takes 1–3 days depending on feature scope: reading events, creating them, synchronizing multiple accounts. Cost is calculated individually.