public static long durationOf(int hours, int minutes, int seconds) {
        return hours * MILLIS_PER_HOUR + minutes * MILLIS_PER_MINUTE + seconds * MILLIS_PER_SECOND;
    }
Calculates a duration from hours, minutes and seconds.

@param hours   full hours of the duration
@param minutes full minutes of the duration
@param seconds full seconds of the duration
@return duration in milliseconds.
android/third_party/time-duration-picker/src/main/java/mobi/upod/timedurationpicker/TimeDurationUtil.java