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Nuts'n'Bolts Utilities
There is a newer version: 6.2.0
/*
 * Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 David Berkman
 *
 * This file is part of the SmallMind Code Project.
 *
 * The SmallMind Code Project is free software, you can redistribute
 * it and/or modify it under either, at your discretion...
 *
 * 1) The terms of GNU Affero General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * ...or...
 *
 * 2) The terms of the Apache License, Version 2.0.
 *
 * The SmallMind Code Project is distributed in the hope that it will
 * be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License or Apache License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * and the Apache License along with the SmallMind Code Project. If not, see
 *  or .
 *
 * Additional permission under the GNU Affero GPL version 3 section 7
 * ------------------------------------------------------------------
 * If you modify this Program, or any covered work, by linking or
 * combining it with other code, such other code is not for that reason
 * alone subject to any of the requirements of the GNU Affero GPL
 * version 3.
 */
package org.smallmind.nutsnbolts.util;

import java.util.Comparator;

public class AlphaNumericComparator implements Comparator {

  private final AlphaNumericConverter alphaNumConverter;

  public AlphaNumericComparator () {

    this(new DefaultAlphaNumericConverter());
  }

  public AlphaNumericComparator (AlphaNumericConverter alphaNumConverter) {

    this.alphaNumConverter = alphaNumConverter;
  }

  public int compare (T obj1, T obj2) {

    String first;
    String second;
    char firstChar;
    char secondChar;
    int minLength;
    int firstDigit;
    int secondDigit;
    int firstValue;
    int secondValue;
    int count;

    if ((obj1 == null) && (obj2 == null)) {
      return 0;
    } else if (obj1 == null) {
      return -1;
    } else if (obj2 == null) {
      return 1;
    }

    first = alphaNumConverter.toString(obj1);
    second = alphaNumConverter.toString(obj2);

    if ((first.length() == 0) && (second.length() == 0)) {
      return 0;
    } else if (first.length() == 0) {
      return -1;
    } else if (second.length() == 0) {
      return 1;
    }

    minLength = Math.min(first.length(), second.length());

    for (count = 0; count < minLength; count++) {
      firstChar = first.charAt(count);
      secondChar = second.charAt(count);
      if ((Character.isDigit(firstChar)) && (!Character.isDigit(secondChar))) {
        return -1;
      } else if ((!Character.isDigit(firstChar)) && (Character.isDigit(secondChar))) {
        return 1;
      } else if ((Character.isDigit(firstChar)) && (Character.isDigit(secondChar))) {
        firstDigit = Integer.parseInt(first.substring(count, count + 1));
        secondDigit = Integer.parseInt(second.substring(count, count + 1));
        if (firstDigit < secondDigit) {
          return -1;
        } else if (firstDigit > secondDigit) {
          return 1;
        }
      } else {
        firstValue = Character.toLowerCase(firstChar);
        secondValue = Character.toLowerCase(secondChar);
        if (firstValue < secondValue) {
          return -1;
        } else if (firstValue > secondValue) {
          return 1;
        }
      }
    }
    if (first.length() < second.length()) {
      return -1;
    } else if (first.length() > second.length()) {
      return 1;
    }
    return 0;
  }
}