Given the problem of converting milliseconds to minutes, I imagine that most of us would simply divide the number of milliseconds by 60,000. That's because most of us are not experts in the art of complexification. We've all certainly seen the work of such "artists" on this site before and, I have to say, that they never fail to impress. Take, for example, how Jesper's predecessors solved the "millisecond conversion" problem. Impressive, eh?

private int convertToMinutes(long milliDiff)
{
  boolean negative = false;
  int minutesDiff = -1;

  if (milliDiff < 0)
  {
    negative = true;
    milliDiff = -milliDiff; // Make positive (is easier)
  }

  if (milliDiff == 0) // Watch out for exceptional value 0
    minutesDiff = 0;
  else
    minutesDiff = (int) (milliDiff / 1000) / 60;

  if (negative) minutesDiff = -minutesDiff; // Make it negative again

  return minutesDiff;
}