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

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:

• Serialized Form

Method Summary

Modifier and Type	Method	Description
String	calculate(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(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 org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit

calculateModulus, getModulus, sumDigits, toCheckDigit, toInt

Methods inherited from class java.lang.Object

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

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

public String calculate(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(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