Upper Case Conversion Required

I wrote the code snip below to do some extra checking on string to
double conversion. I did not expect the need to call toUpperCase.
What was I not anticipating? It just didn't seem logical to me,
given the number of tools out there that create their floating point
numbers with a lower case "e".

-------------------------

     private java.util.Locale myLocale =
       java.util.Locale.getDefault( );

     private java.text.NumberFormat DFormat =
       java.text.NumberFormat.getInstance( myLocale );
     private java.text.ParsePosition DPosition =
       new java.text.ParsePosition( 0 );

     public double DparseDouble( String S ) throws NumberFormatException
         {
         // Trim it and check for a blank string.
         // Upper case is needed to match the "E" in scientific notation.

         String T = S.trim( ).toUpperCase( );
         if( T.length( ) == 0 )
             {
             throw new NumberFormatException( );
             }

         // Otherwise, try to parse it.

         DPosition.setIndex( 0 );
         Number parsedNumber = DFormat.parse( T, DPosition );

         // Failure will occur if none or only a part of the string
         // is properly parsed.

         if( DPosition.getIndex( ) < T.length( ) )
             {
             throw new NumberFormatException( );
             }

         return parsedNumber.doubleValue( );
         }