| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| LuhnCheckDigit |
|
| 1.5;1.5 |
| 1 | /* | |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
| 3 | * contributor license agreements. See the NOTICE file distributed with | |
| 4 | * this work for additional information regarding copyright ownership. | |
| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
| 6 | * (the "License"); you may not use this file except in compliance with | |
| 7 | * the License. You may obtain a copy of the License at | |
| 8 | * | |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 10 | * | |
| 11 | * Unless required by applicable law or agreed to in writing, software | |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 14 | * See the License for the specific language governing permissions and | |
| 15 | * limitations under the License. | |
| 16 | */ | |
| 17 | package org.apache.commons.validator.routines.checkdigit; | |
| 18 | ||
| 19 | /** | |
| 20 | * Modulus 10 <b>Luhn</b> Check Digit calculation/validation. | |
| 21 | * | |
| 22 | * Luhn check digits are used, for example, by: | |
| 23 | * <ul> | |
| 24 | * <li><a href="http://en.wikipedia.org/wiki/Credit_card">Credit Card Numbers</a></li> | |
| 25 | * <li><a href="http://en.wikipedia.org/wiki/IMEI">IMEI Numbers</a> - International | |
| 26 | * Mobile Equipment Identity Numbers</li> | |
| 27 | * </ul> | |
| 28 | * Check digit calculation is based on <i>modulus 10</i> with digits in | |
| 29 | * an <i>odd</i> position (from right to left) being weighted 1 and <i>even</i> | |
| 30 | * position digits being weighted 2 (weighted values greater than 9 have 9 subtracted). | |
| 31 | * | |
| 32 | * <p> | |
| 33 | * See <a href="http://en.wikipedia.org/wiki/Luhn_algorithm">Wikipedia</a> | |
| 34 | * for more details. | |
| 35 | * </p> | |
| 36 | * | |
| 37 | * @version $Revision: 1739356 $ | |
| 38 | * @since Validator 1.4 | |
| 39 | */ | |
| 40 | public final class LuhnCheckDigit extends ModulusCheckDigit { | |
| 41 | ||
| 42 | private static final long serialVersionUID = -2976900113942875999L; | |
| 43 | ||
| 44 | /** Singleton Luhn Check Digit instance */ | |
| 45 | 1 | public static final CheckDigit LUHN_CHECK_DIGIT = new LuhnCheckDigit(); |
| 46 | ||
| 47 | /** weighting given to digits depending on their right position */ | |
| 48 | 1 | private static final int[] POSITION_WEIGHT = new int[] {2, 1}; |
| 49 | ||
| 50 | /** | |
| 51 | * Construct a modulus 10 Luhn Check Digit routine. | |
| 52 | */ | |
| 53 | public LuhnCheckDigit() { | |
| 54 | 1 | super(10); // CHECKSTYLE IGNORE MagicNumber |
| 55 | 1 | } |
| 56 | ||
| 57 | /** | |
| 58 | * <p>Calculates the <i>weighted</i> value of a charcter in the | |
| 59 | * code at a specified position.</p> | |
| 60 | * | |
| 61 | * <p>For Luhn (from right to left) <b>odd</b> digits are weighted | |
| 62 | * with a factor of <b>one</b> and <b>even</b> digits with a factor | |
| 63 | * of <b>two</b>. Weighted values > 9, have 9 subtracted</p> | |
| 64 | * | |
| 65 | * @param charValue The numeric value of the character. | |
| 66 | * @param leftPos The position of the character in the code, counting from left to right | |
| 67 | * @param rightPos The positionof the character in the code, counting from right to left | |
| 68 | * @return The weighted value of the character. | |
| 69 | */ | |
| 70 | @Override | |
| 71 | protected int weightedValue(int charValue, int leftPos, int rightPos) { | |
| 72 | 8666 | int weight = POSITION_WEIGHT[rightPos % 2]; // CHECKSTYLE IGNORE MagicNumber |
| 73 | 8666 | int weightedValue = charValue * weight; |
| 74 | 8666 | return weightedValue > 9 ? (weightedValue - 9) : weightedValue; // CHECKSTYLE IGNORE MagicNumber |
| 75 | } | |
| 76 | } |