Class CASNumberCheckDigit

java.lang.Object
org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit
org.apache.commons.validator.routines.checkdigit.CASNumberCheckDigit
All Implemented Interfaces:
Serializable, CheckDigit

public final class CASNumberCheckDigit extends ModulusCheckDigit
Modulus 10 CAS Registry Number (or Chemical Abstracts Service (CAS RN)) Check Digit calculation/validation.

CAS Numbers are unique identification numbers used to identify chemical substance described in the open scientific literature.

Check digit calculation is based on modulus 10 with digits being weighted based on their position (from right to left).

The check digit is found by taking the last digit times 1, the preceding digit times 2, the preceding digit times 3 etc., adding all these up and computing the sum modulo 10. For example, the CAS number of water is 7732-18-5: the checksum 5 is calculated as (8×1 + 1×2 + 2×3 + 3×4 + 7×5 + 7×6) = 105; 105 mod 10 = 5.

For further information see Wikipedia - CAS Registry Number.

Since:
1.9.0
See Also:
  • Method Details

    • getInstance

      public static CheckDigit getInstance()
      Gets the singleton instance of this validator.
      Returns:
      A singleton instance of the CAS Number validator.
    • weightedValue

      protected int weightedValue(int charValue, int leftPos, int rightPos)
      Calculates the weighted value of a character in the code at a specified position.

      CAS numbers are weighted in the following manner:

      
          right position: 1  2  3  4  5  6  7  8  9 10
                  weight: 1  2  3  4  5  6  7  8  9  0
       
      Specified by:
      weightedValue in class ModulusCheckDigit
      Parameters:
      charValue - The numeric value of the character.
      leftPos - The position of the character in the code, counting from left to right
      rightPos - The positionof the character in the code, counting from right to left
      Returns:
      The weighted value of the character.
    • calculate

      Calculate a modulus Check Digit for a code which does not yet have one.
      Specified by:
      calculate in interface CheckDigit
      Overrides:
      calculate in class ModulusCheckDigit
      Parameters:
      code - The code for which to calculate the Check Digit; the check digit should not be included
      Returns:
      The calculated Check Digit
      Throws:
      CheckDigitException - if an error occurs calculating the check digit
    • isValid

      public boolean isValid(String code)
      Validate a modulus check digit for a code.
      Specified by:
      isValid in interface CheckDigit
      Overrides:
      isValid in class ModulusCheckDigit
      Parameters:
      code - The code to validate
      Returns:
      true if the check digit is valid, otherwise false