code: public static boolean isValidDouble(String number) {
          boolean valid = false;
          if (isDouble(number) && isPositive(Double.parseDouble(number))) {
              valid = true;
          }
          return valid;
      }
docs: Checks if a string is a valid double.
  
  @param number The string to check
  @return True if the number is a valid double (positive) else false.