org.apache.commons.validator.routines.checkdigit

Class ModulusCheckDigit

java.lang.Object

org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit

All Implemented Interfaces:

java.io.Serializable, CheckDigit

Direct Known Subclasses:

LuhnCheckDigit

public abstract class ModulusCheckDigit
extends java.lang.Object
implements CheckDigit, java.io.Serializable

Abstract Modulus Check digit calculation/validation.

Provides a base class for building modulus Check Digit routines.

This implementation only handles single-digit numeric codes, such as EAN-13. For alphanumeric codes such as EAN-128 you will need to implement/override the toInt() and toChar() methods.

Since:

Validator 1.4

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ModulusCheckDigit(int modulus) Construct a CheckDigit routine for a specified modulus.

Method Summary

Modifier and Type	Method and Description
java.lang.String	calculate(java.lang.String code) Calculate a modulus Check Digit for a code which does not yet have one.
protected int	calculateModulus(java.lang.String code, boolean includesCheckDigit) Calculate the modulus for a code.
int	getModulus() Return the modulus value this check digit routine is based on.
boolean	isValid(java.lang.String code) Validate a modulus check digit for a code.
static int	sumDigits(int number) Add together the individual digits in a number.
protected java.lang.String	toCheckDigit(int charValue) Convert an integer value to a check digit.
protected int	toInt(char character, int leftPos, int rightPos) Convert a character at a specified position to an integer value.
protected abstract 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

Constructor Detail

ModulusCheckDigit

public ModulusCheckDigit(int modulus)

Construct a CheckDigit routine for a specified modulus.

Parameters:

modulus - The modulus value to use for the check digit calculation

Method Detail

getModulus

public int getModulus()

Return the modulus value this check digit routine is based on.

Returns:

The modulus value this check digit routine is based on

isValid

public boolean isValid(java.lang.String code)

Validate a modulus check digit for a code.

Specified by:

isValid in interface CheckDigit

Parameters:

code - The code to validate

Returns:

true if the check digit is valid, otherwise false

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

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

calculateModulus

protected int calculateModulus(java.lang.String code,
                               boolean includesCheckDigit)
                        throws CheckDigitException

Calculate the modulus for a code.

Parameters:

code - The code to calculate the modulus for.

includesCheckDigit - Whether the code includes the Check Digit or not.

Returns:

The modulus value

Throws:

CheckDigitException - if an error occurs calculating the modulus for the specified code

weightedValue

protected abstract int weightedValue(int charValue,
                                     int leftPos,
                                     int rightPos)
                              throws CheckDigitException

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 (e.g. ISBN-10), while others use different weighting factors for odd/even positions (e.g. EAN or Luhn). Implement the appropriate mechanism required by overriding this method.

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

Throws:

CheckDigitException - if an error occurs calculating the weighted value

toInt

protected int toInt(char character,
                    int leftPos,
                    int rightPos)
             throws CheckDigitException

Convert 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.

Parameters:

character - The character to convert

leftPos - The position of the character in the code, counting from left to right (for identifiying 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

toCheckDigit

protected java.lang.String toCheckDigit(int charValue)
                                 throws CheckDigitException

Convert 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.

Parameters:

charValue - The integer value of the character

Returns:

The converted character

Throws:

CheckDigitException - if integer character value doesn't represent a numeric character

sumDigits

public static int sumDigits(int number)

Add together the individual digits in a number.

Parameters:

number - The number whose digits are to be added

Returns:

The sum of the digits