How to get the time difference in Android.

e.g The time a person is awake by getting the difference between the time they wake up and the time they go to sleep

private fun getNumOfHoursAwake(
    startTime: String,
    endTime: String
): Int {
    /**
     * startTime - e.g 21:00
     * endTime -  e.g 04:00
     * expected to return 17
     */
    val simpleDateFormat = SimpleDateFormat("HH:mm")
    val dateMax: Date = simpleDateFormat.parse(startTime)
    val dateMin: Date = simpleDateFormat.parse(endTime)
    val startDate = simpleDateFormat.parse(startTime)
    val endDate = simpleDateFormat.parse(endTime)

    var difference = dateMax.time - dateMin.time
    if (difference < 0) {
        difference = (dateMax.time - startDate.time) + (endDate.time - dateMin.time)

    }
    val days = (difference / (1000 * 60 * 60 * 24)).toInt()
    val hours = ((difference - 1000 * 60 * 60 * 24 * days) / (1000 * 60 * 60))
    return hours.toInt()
}

Happy coding!