Question

I unfortunately cant use expressions like Long.Nan as the string is actually a return value from a different C module. Is there a string I can pass to parseLong() to return an NaN ?

Answer 1

There is no Long.NaN — you are confused.

For Double.NaN, how about this:

public double myParseDouble(String s)
{
   double result;
   try
   {
      result = Double.parseDouble(s);
   }
   catch (NumberFormatException nfe)
   {
      result = Double.NaN;
   }
   return result;
}

(edit: and the obvious approach is to pass in any string that is an invalid double, e.g. the empty string or NaN)