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 * <b>Check Digit</b> calculation and validation. 021 * <p> 022 * The logic for validating check digits has previously been 023 * embedded within the logic for specific code validation, which 024 * includes other validations such as verifying the format 025 * or length of a code. {@link CheckDigit} provides for separating out 026 * the check digit calculation logic enabling it to be more easily 027 * tested and reused. 028 * </p> 029 * <p> 030 * Although Commons Validator is primarily concerned with validation, 031 * {@link CheckDigit} also defines behavior for calculating/generating check 032 * digits, since it makes sense that users will want to (re-)use the 033 * same logic for both. The {@link org.apache.commons.validator.routines.ISBNValidator} 034 * makes specific use of this feature by providing the facility to validate ISBN-10 codes 035 * and then convert them to the new ISBN-13 standard. 036 * </p> 037 * <p> 038 * CheckDigit is used by the new generic @link CodeValidator} implementation. 039 * </p> 040 * 041 * <h2>Implementations</h2> 042 * See the 043 * <a href="package-summary.html">Package Summary</a> for a full 044 * list of implementations provided within Commons Validator. 045 * 046 * @see org.apache.commons.validator.routines.CodeValidator 047 * @version $Revision$ 048 * @since Validator 1.4 049 */ 050public interface CheckDigit { 051 052 /** 053 * Calculates the <i>Check Digit</i> for a code. 054 * 055 * @param code The code to calculate the Check Digit for. 056 * The string must not include the check digit 057 * @return The calculated Check Digit 058 * @throws CheckDigitException if an error occurs. 059 */ 060 String calculate(String code) throws CheckDigitException; 061 062 /** 063 * Validates the check digit for the code. 064 * 065 * @param code The code to validate, the string must include the check digit. 066 * @return <code>true</code> if the check digit is valid, otherwise 067 * <code>false</code>. 068 */ 069 boolean isValid(String code); 070 071}