Class ISSNCheckDigit

java.lang.Object
org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit
org.apache.commons.validator.routines.checkdigit.ISSNCheckDigit
All Implemented Interfaces:
Serializable, CheckDigit
public final class ISSNCheckDigit extends ModulusCheckDigit
International Standard Serial Number (ISSN) is an eight-digit serial number used to uniquely identify a serial publication. 
The format is:

ISSN dddd-dddC
where:
d = decimal digit (0-9)
C = checksum (0-9 or X)

The checksum is formed by adding the first 7 digits multiplied by
the position in the entire number (counting from the right).
For example, abcd-efg would be 8a + 7b + 6c + 5d + 4e +3f +2g.
The check digit is modulus 11, where the value 10 is represented by 'X'
For example:
ISSN 0317-8471
ISSN 1050-124X

Note: This class expects the input to be numeric only, with all formatting removed. For example: 

03178471
1050124X
Since:
1.5.0
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final CheckDigit
    ISSN_CHECK_DIGIT
    Singleton ISSN Check Digit instance.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ISSNCheckDigit()
    Creates the instance using a checkdigit modulus of 11.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    isValid(String code)
    Validates a modulus check digit for a code.
    protected String
    toCheckDigit(int charValue)
    Converts an integer value to a check digit.
    protected int
    toInt(char character, int leftPos, int rightPos)
    Converts a character at a specified position to an integer value.
    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 ModulusCheckDigit

    calculate, calculateModulus, getModulus, sumDigits
    Modifier and Type
    Method
    Description
    String
    calculate(String code)
    Calculates a modulus Check Digit for a code which does not yet have one.
    protected int
    calculateModulus(String code, boolean includesCheckDigit)
    Calculates the modulus for a code.
    int
    getModulus()
    Gets the modulus value this check digit routine is based on.
    static int
    sumDigits(int number)
    Adds together the individual digits in a number.

    Methods inherited from class Object

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

  • Field Details

  • Constructor Details

    • ISSNCheckDigit

      public ISSNCheckDigit()
      Creates the instance using a checkdigit modulus of 11.

  • Method Details

    • isValid

      public boolean isValid(String code)
      Validates a modulus check digit for a code.

      The 9 - leftPos weighting gives a ninth character a weight of zero, so an over-length code left the trailing characters unweighted and still passed the modulus test (for example every 03178471 + digit validated). The length is checked here so only a genuine eight-character ISSN reaches the check digit test.

      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.

    • toCheckDigit

      protected String toCheckDigit(int charValue) throws CheckDigitException
      Description copied from class: ModulusCheckDigit
      Converts an integer value to a check digit.

      Note: this implementation only handles single-digit numeric values For non-numeric characters, override this method to provide integer-->character conversion.

      Overrides:
      toCheckDigit in class ModulusCheckDigit
      Parameters:
      charValue - The integer value of the character.
      Returns:
      The converted character.
      Throws:
      CheckDigitException - if integer character value. doesn't represent a numeric character.

    • toInt

      protected int toInt(char character, int leftPos, int rightPos) throws CheckDigitException
      Description copied from class: ModulusCheckDigit
      Converts a character at a specified position to an integer value.

      Note: this implementation only handlers numeric values For non-numeric characters, override this method to provide character-->integer conversion.

      Overrides:
      toInt in class ModulusCheckDigit
      Parameters:
      character - The character to convert.
      leftPos - The position of the character in the code, counting from left to right (for identifying the position in the string).
      rightPos - The position of the character in the code, counting from right to left (not used here).
      Returns:
      The integer value of the character.
      Throws:
      CheckDigitException - if character is non-numeric.

    • weightedValue

      protected int weightedValue(int charValue, int leftPos, int rightPos) throws CheckDigitException
      Description copied from class: ModulusCheckDigit
      Calculates the weighted value of a character in the code at a specified position.

      Some modulus routines weight the value of a character depending on its position in the code (for example, ISBN-10), while others use different weighting factors for odd/even positions (for example, EAN or Luhn). Implement the appropriate mechanism required by overriding this method.

      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.
      Throws:
      CheckDigitException - if an error occurs calculating. the weighted value.