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 * Modulus 10 <b>ABA Number</b> (or <b>Routing Transit Number</b> (RTN)) Check Digit 021 * calculation/validation. 022 * 023 * <p> 024 * ABA Numbers (or Routing Transit Numbers) are a nine digit numeric code used 025 * to identify American financial institutions for things such as checks or deposits 026 * (ABA stands for the American Bankers Association). 027 * </p> 028 * 029 * Check digit calculation is based on <i>modulus 10</i> with digits being weighted 030 * based on their position (from right to left) as follows: 031 * 032 * <ul> 033 * <li>Digits 1, 4 and & 7 are weighted 1</li> 034 * <li>Digits 2, 5 and & 8 are weighted 7</li> 035 * <li>Digits 3, 6 and & 9 are weighted 3</li> 036 * </ul> 037 * 038 * <p> 039 * For further information see 040 * <a href="http://en.wikipedia.org/wiki/Routing_transit_number">Wikipedia - 041 * Routing transit number</a>. 042 * </p> 043 * 044 * @version $Revision$ 045 * @since Validator 1.4 046 */ 047public final class ABANumberCheckDigit extends ModulusCheckDigit { 048 049 private static final long serialVersionUID = -8255937433810380145L; 050 051 /** Singleton Routing Transit Number Check Digit instance */ 052 public static final CheckDigit ABAN_CHECK_DIGIT = new ABANumberCheckDigit(); 053 054 /** weighting given to digits depending on their right position */ 055 private static final int[] POSITION_WEIGHT = new int[] {3, 1, 7}; 056 057 /** 058 * Construct a modulus 10 Check Digit routine for ABA Numbers. 059 */ 060 public ABANumberCheckDigit() { 061 super(10); // CHECKSTYLE IGNORE MagicNumber 062 } 063 064 /** 065 * Calculates the <i>weighted</i> value of a character in the 066 * code at a specified position. 067 * <p> 068 * ABA Routing numbers are weighted in the following manner: 069 * <pre><code> 070 * left position: 1 2 3 4 5 6 7 8 9 071 * weight: 3 7 1 3 7 1 3 7 1 072 * </code></pre> 073 * 074 * @param charValue The numeric value of the character. 075 * @param leftPos The position of the character in the code, counting from left to right 076 * @param rightPos The positionof the character in the code, counting from right to left 077 * @return The weighted value of the character. 078 */ 079 @Override 080 protected int weightedValue(int charValue, int leftPos, int rightPos) { 081 int weight = POSITION_WEIGHT[rightPos % 3]; // CHECKSTYLE IGNORE MagicNumber 082 return charValue * weight; 083 } 084 085}