001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.validator.routines.checkdigit; 018 019/** 020 * International Standard Serial Number (ISSN) 021 * is an eight-digit serial number used to 022 * uniquely identify a serial publication. 023 * <pre> 024 * The format is: 025 * 026 * ISSN dddd-dddC 027 * where: 028 * d = decimal digit (0-9) 029 * C = checksum (0-9 or X) 030 * 031 * The checksum is formed by adding the first 7 digits multiplied by 032 * the position in the entire number (counting from the right). 033 * For example, abcd-efg would be 8a + 7b + 6c + 5d + 4e +3f +2g. 034 * The check digit is modulus 11, where the value 10 is represented by 'X' 035 * For example: 036 * ISSN 0317-8471 037 * ISSN 1050-124X 038 * </pre> 039 * <p> 040 * <b>Note:</b> This class expects the input to be numeric only, 041 * with all formatting removed. 042 * For example: 043 * <pre> 044 * 03178471 045 * 1050124X 046 * </pre> 047 * @since 1.5.0 048 */ 049public final class ISSNCheckDigit extends ModulusCheckDigit { 050 051 052 private static final long serialVersionUID = 1L; 053 054 /** Singleton ISSN Check Digit instance */ 055 public static final CheckDigit ISSN_CHECK_DIGIT = new ISSNCheckDigit(); 056 057 /** 058 * Creates the instance using a checkdigit modulus of 11 059 */ 060 public ISSNCheckDigit() { 061 super(11); // CHECKSTYLE IGNORE MagicNumber 062 } 063 064 @Override 065 protected int weightedValue(int charValue, int leftPos, int rightPos) throws CheckDigitException { 066 return charValue * (9 - leftPos); // CHECKSTYLE IGNORE MagicNumber 067 } 068 069 @Override 070 protected String toCheckDigit(int charValue) throws CheckDigitException { 071 if (charValue == 10) { // CHECKSTYLE IGNORE MagicNumber 072 return "X"; 073 } 074 return super.toCheckDigit(charValue); 075 } 076 077 @Override 078 protected int toInt(char character, int leftPos, int rightPos) 079 throws CheckDigitException { 080 if (rightPos == 1 && character == 'X') { 081 return 10; // CHECKSTYLE IGNORE MagicNumber 082 } 083 return super.toInt(character, leftPos, rightPos); 084 } 085}