org.hibernate.validator.internal.util.ModUtil Maven / Gradle / Ivy
/*
* JBoss, Home of Professional Open Source
* Copyright 2012, Red Hat, Inc. and/or its affiliates, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.hibernate.validator.internal.util;
import java.util.List;
/**
* Helper class for modulo 10/11.
*
* @author Hardy Ferentschik
*/
public final class ModUtil {
private ModUtil() {
}
/**
* Check if the input passes the mod11 test
*
* @param digits The digits over which to calculate the mod 11 algorithm
* @param multiplier the multiplier for the modulo algorithm
*
* @return {@code true} if the mod 11 result matches the check digit, {@code false} otherwise
*/
public static boolean passesMod11Test(final List digits, int multiplier) {
int modResult = mod11( digits, multiplier );
return modResult == 0;
}
/**
* Mod10 (Luhn) algorithm implementation
*
* @param digits The digits over which to calculate the checksum
* @param multiplier Multiplier used in the algorithm
*
* @return {@code true} if the mod 10 result matches the check digit, {@code false} otherwise
*/
public static boolean passesMod10Test(final List digits, final int multiplier) {
int modResult = mod10( digits, multiplier );
return modResult == 0;
}
/**
* Calculate Mod11
*
* @param digits the digits for which to calculate the checksum
* @param multiplier multiplier for the modulo algorithm
*
* @return the result of the mod11 calculation
*/
private static int mod11(final List digits, final int multiplier) {
int sum = 0;
int weight = 1;
for ( int index = digits.size() - 1; index >= 0; index-- ) {
sum += digits.get( index ) * weight++;
if ( weight > multiplier ) {
weight = 2;
}
}
int mod = 11 - ( sum % 11 );
return ( mod > 9 ) ? 0 : mod;
}
/**
* Calculate Mod10 (Luhn)
*
* @param digits the digits for which to calculate the checksum
* @param multiplier multiplier for the modulo algorithm
*
* @return the result of the mod10 calculation
*/
private static int mod10(final List digits, final int multiplier) {
int sum = 0;
boolean even = false;
for ( int index = digits.size() - 1; index >= 0; index-- ) {
int digit = digits.get( index );
if ( even ) {
digit *= multiplier;
}
if ( digit > 9 ) {
digit = digit / 10 + digit % 10;
}
sum += digit;
even = !even;
}
return sum % 10;
}
}