static final long MILLISECONDS_PER_DAY = 24 * 60 * 60 * 1000L;
static final long MILLISECONDS_PER_HOUR = 60 * 60 * 1000L;
static final long MILLISECONDS_PER_MINUTE = 60 * 1000L;
static final long MILLISECONDS_PER_SECOND = 1000L;

long millis = days * MILLISECONDS_PER_DAY + hours * MILLISECONDS_PER_HOUR
              + minutes * MILLISECONDS_PER_MINUTE
              + seconds * MILLISECONDS_PER_SECOND
              + milliseconds;