Convert date between java and .net - 2 days off

Question

I need to transform a .NET DateTime to an equivalent Java Calendar representation.

The .NET DateTime uses Ticks

Answer 1

Answering the 'why':

From the (decompiled - thanks dotPeek!) .NET 4 source code (comments are mine):

public static DateTime operator -(DateTime d, TimeSpan t)
{
  //range checks
  long internalTicks = d.InternalTicks;
  long num = t._ticks;
  if (internalTicks < num || internalTicks - 3155378975999999999L > num)
    throw new ArgumentOutOfRangeException("t", 
            Environment.GetResourceString("ArgumentOutOfRange_DateArithmetic"));

    else

    //plain arithmetic using the Ticks property of the two dates.
    return new DateTime((ulong) (internalTicks - num) | d.InternalKind);
}

So yeah, absolutely no special 'gregorian' treatment for DateTime operators.

About the 'how to fix':

I ended up using something along these lines: (pseudo-Java)

Calendar cal = new GregorianCalendar();
cal.set(dt.Year, dt.Month - 1 /*it's 0-based*/, dt.Day, dt.Hour, dt.Minute, dt.Second);
cal.set(Calendar.MILLISECOND, dt.Millisecond);