Compares two Strings, and returns the portion where they differ. : String Compare « Data Type « Java Tutorial

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Java Tutorial » Data Type » String Compare 
2.23.11.Compares two Strings, and returns the portion where they differ.Previous/Next
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

public class Main {
  // Difference
  //-----------------------------------------------------------------------
  /**
   * Compares two Strings, and returns the portion where they differ.
   * (More precisely, return the remainder of the second String,
   * starting from where it's different from the first.)
   *
   * For example,
   * <code>difference("i am a machine", "i am a robot") -> "robot"</code>.
   *
   * <pre>
   * StringUtils.difference(null, null) = null
   * StringUtils.difference("", "") = ""
   * StringUtils.difference("", "abc") = "abc"
   * StringUtils.difference("abc", "") = ""
   * StringUtils.difference("abc", "abc") = ""
   * StringUtils.difference("ab", "abxyz") = "xyz"
   * StringUtils.difference("abcde", "abxyz") = "xyz"
   * StringUtils.difference("abcde", "xyz") = "xyz"
   * </pre>
   *
   @param str1  the first String, may be null
   @param str2  the second String, may be null
   @return the portion of str2 where it differs from str1; returns the
   * empty String if they are equal
   @since 2.0
   */
  public static String difference(String str1, String str2) {
      if (str1 == null) {
          return str2;
      }
      if (str2 == null) {
          return str1;
      }
      int at = indexOfDifference(str1, str2);
      if (at == -1) {
          return "";
      }
      return str2.substring(at);
  }
  /**
   * Compares two Strings, and returns the index at which the
   * Strings begin to differ.
   *
   * For example,
   * <code>indexOfDifference("i am a machine", "i am a robot") -> 7</code>
   *
   * <pre>
   * StringUtils.indexOfDifference(null, null) = -1
   * StringUtils.indexOfDifference("", "") = -1
   * StringUtils.indexOfDifference("", "abc") = 0
   * StringUtils.indexOfDifference("abc", "") = 0
   * StringUtils.indexOfDifference("abc", "abc") = -1
   * StringUtils.indexOfDifference("ab", "abxyz") = 2
   * StringUtils.indexOfDifference("abcde", "abxyz") = 2
   * StringUtils.indexOfDifference("abcde", "xyz") = 0
   * </pre>
   *
   @param str1  the first String, may be null
   @param str2  the second String, may be null
   @return the index where str2 and str1 begin to differ; -1 if they are equal
   @since 2.0
   */
  public static int indexOfDifference(String str1, String str2) {
      if (str1 == str2) {
          return -1;
      }
      if (str1 == null || str2 == null) {
          return 0;
      }
      int i;
      for (i = 0; i < str1.length() && i < str2.length(); ++i) {
          if (str1.charAt(i!= str2.charAt(i)) {
              break;
          }
      }
      if (i < str2.length() || i < str1.length()) {
          return i;
      }
      return -1;
  }

}
2.23.String Compare
2.23.1.Comparing Strings for Equality
2.23.2.To check for equality between two strings ignoring the case
2.23.3.Sequencing Strings
2.23.4.String length, charAt, equals
2.23.5.equals() and equalsIgnoreCase().
2.23.6.equals() vs ==
2.23.7.Region Matches
2.23.8.Compares all Strings in an array and returns the index at which the Strings begin to differ.
2.23.9.Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.
2.23.10.Compares two Strings, and returns the index at which the Strings begin to differ.
2.23.11.Compares two Strings, and returns the portion where they differ.
2.23.12.Compress 2 adjacent (single or double) quotes into a single (s or d) quote when found in the middle of a String.
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