Class LuhnCheckDigit
java.lang.Object
org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit
org.apache.commons.validator.routines.checkdigit.LuhnCheckDigit
- All Implemented Interfaces:
Serializable
,CheckDigit
Modulus 10 Luhn Check Digit calculation/validation.
Luhn check digits are used, for example, by:
- Credit Card Numbers
- IMEI Numbers - International Mobile Equipment Identity Numbers
See Wikipedia for more details.
- Since:
- Validator 1.4
- Version:
- $Revision: 1649191 $
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final CheckDigit
Singleton Luhn Check Digit instanceprivate static final int[]
weighting given to digits depending on their right positionprivate static final long
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected int
weightedValue
(int charValue, int leftPos, int rightPos) Calculates the weighted value of a charcter in the code at a specified position.Methods inherited from class org.apache.commons.validator.routines.checkdigit.ModulusCheckDigit
calculate, calculateModulus, getModulus, isValid, sumDigits, toCheckDigit, toInt
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Field Details
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serialVersionUID
private static final long serialVersionUID- See Also:
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LUHN_CHECK_DIGIT
Singleton Luhn Check Digit instance -
POSITION_WEIGHT
private static final int[] POSITION_WEIGHTweighting given to digits depending on their right position
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Constructor Details
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LuhnCheckDigit
public LuhnCheckDigit()Construct a modulus 10 Luhn Check Digit routine.
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Method Details
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weightedValue
protected int weightedValue(int charValue, int leftPos, int rightPos) Calculates the weighted value of a charcter in the code at a specified position.
For Luhn (from right to left) odd digits are weighted with a factor of one and even digits with a factor of two. Weighted values > 9, have 9 subtracted
- Specified by:
weightedValue
in classModulusCheckDigit
- Parameters:
charValue
- The numeric value of the character.leftPos
- The position of the character in the code, counting from left to rightrightPos
- The positionof the character in the code, counting from right to left- Returns:
- The weighted value of the character.
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