code: public static final Double getDouble(byte[] data, int offset)
     {
        Double result = null;
        long longValue = getLong(data, offset);
        if (longValue != NULL_DOUBLE)
        {
           double doubleValue = Double.longBitsToDouble(longValue);
           if (!Double.isNaN(doubleValue))
           {
              result = Double.valueOf(doubleValue);
           }
        }
        return result;
     }
docs: This method reads an eight byte double from the input array.
  
  @param data the input array
  @param offset offset of double data in the array
  @return double value