Abbreviates a String using ellipses. : String Format « Data Type « Java Tutorial

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 * 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
 * 
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 * 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 {
  // Abbreviating
  //-----------------------------------------------------------------------
  /**
   * Abbreviates a String using ellipses. This will turn
   * "Now is the time for all good men" into "Now is the time for..."
   *
   * Specifically:
   * <ul>
   *   <li>If <code>str</code> is less than <code>maxWidth</code> characters
   *       long, return it.</li>
   *   <li>Else abbreviate it to <code>(substring(str, 0, max-3) + "...")</code>.</li>
   *   <li>If <code>maxWidth</code> is less than <code>4</code>, throw an
   *       <code>IllegalArgumentException</code>.</li>
   *   <li>In no case will it return a String of length greater than
   *       <code>maxWidth</code>.</li>
   * </ul>
   * 
   *
   * <pre>
   * StringUtils.abbreviate(null, *)      = null
   * StringUtils.abbreviate("", 4)        = ""
   * StringUtils.abbreviate("abcdefg", 6) = "abc..."
   * StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
   * StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
   * StringUtils.abbreviate("abcdefg", 4) = "a..."
   * StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
   * </pre>
   *
   * @param str  the String to check, may be null
   * @param maxWidth  maximum length of result String, must be at least 4
   * @return abbreviated String, <code>null</code> if null String input
   * @throws IllegalArgumentException if the width is too small
   * @since 2.0
   */
  public static String abbreviate(String str, int maxWidth) {
      return abbreviate(str, 0, maxWidth);
  }
  /**
   * Abbreviates a String using ellipses. This will turn
   * "Now is the time for all good men" into "...is the time for..."
   *
   * Works like <code>abbreviate(String, int)</code>, but allows you to specify
   * a "left edge" offset.  Note that this left edge is not necessarily going to
   * be the leftmost character in the result, or the first character following the
   * ellipses, but it will appear somewhere in the result.
   *
   * In no case will it return a String of length greater than
   * <code>maxWidth</code>.
   *
   * <pre>
   * StringUtils.abbreviate(null, *, *)                = null
   * StringUtils.abbreviate("", 0, 4)                  = ""
   * StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
   * StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
   * StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
   * StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
   * StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
   * StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
   * StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
   * StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
   * StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
   * StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
   * StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException
   * </pre>
   *
   * @param str  the String to check, may be null
   * @param offset  left edge of source String
   * @param maxWidth  maximum length of result String, must be at least 4
   * @return abbreviated String, <code>null</code> if null String input
   * @throws IllegalArgumentException if the width is too small
   * @since 2.0
   */
  public static String abbreviate(String str, int offset, int maxWidth) {
      if (str == null) {
          return null;
      }
      if (maxWidth < 4) {
          throw new IllegalArgumentException("Minimum abbreviation width is 4");
      }
      if (str.length() <= maxWidth) {
          return str;
      }
      if (offset > str.length()) {
          offset = str.length();
      }
      if ((str.length() - offset) < (maxWidth - 3)) {
          offset = str.length() - (maxWidth - 3);
      }
      if (offset <= 4) {
          return str.substring(0, maxWidth - 3) + "...";
      }
      if (maxWidth < 7) {
          throw new IllegalArgumentException("Minimum abbreviation width with offset is 7");
      }
      if ((offset + (maxWidth - 3)) < str.length()) {
          return "..." + abbreviate(str.substring(offset), maxWidth - 3);
      }
      return "..." + str.substring(str.length() - (maxWidth - 3));
  }
}