Package org.apache.commons.validator.routines.checkdigit

Class CASNumberCheckDigit

  • All Implemented Interfaces:
    java.io.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:
    Serialized Form

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.String calculate​(java.lang.String code)
      Calculate a modulus Check Digit for a code which does not yet have one.
      static CheckDigit getInstance()
      Gets the singleton instance of this validator.
      boolean isValid​(java.lang.String code)
      Validate a modulus check digit for a code.
      protected int weightedValue​(int charValue, int leftPos, int rightPos)
      Calculates the weighted value of a character in the code at a specified position.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • getInstance

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

      • calculate

        public java.lang.String calculate​(java.lang.String code)
                           throws CheckDigitException
        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​(java.lang.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

      • 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 position of the character in the code, counting from right to left
        Returns:
        The weighted value of the character.