Gets the String that is nested in between two instances of the same String. : Substring « Data Type « Java Tutorial






import java.util.ArrayList;
import java.util.List;


/**
 * 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.
 */




/**
 * Operations on {@link java.lang.String} that are
 * <code>null</code> safe.

 *
 * @see java.lang.String
 * @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a>
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author Daniel L. Rall
 * @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>
 * @author <a href="mailto:ed@apache.org">Ed Korthof</a>
 * @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>
 * @author Stephen Colebourne
 * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
 * @author Holger Krauth
 * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 * @author Arun Mammen Thomas
 * @author Gary Gregory
 * @author Phil Steitz
 * @author Al Chou
 * @author Michael Davey
 * @author Reuben Sivan
 * @author Chris Hyzer
 * @author Scott Johnson
 * @since 1.0
 * @version $Id: StringUtils.java 635447 2008-03-10 06:27:09Z bayard $
 */
public class Main {
  // Substring between
  //-----------------------------------------------------------------------
  /**
   * Gets the String that is nested in between two instances of the
   * same String.
   *
   * A <code>null</code> input String returns <code>null</code>.
   * A <code>null</code> tag returns <code>null</code>.
   *
   * <pre>
   * StringUtils.substringBetween(null, *)            = null
   * StringUtils.substringBetween("", "")             = ""
   * StringUtils.substringBetween("", "tag")          = null
   * StringUtils.substringBetween("tagabctag", null)  = null
   * StringUtils.substringBetween("tagabctag", "")    = ""
   * StringUtils.substringBetween("tagabctag", "tag") = "abc"
   * </pre>
   *
   * @param str  the String containing the substring, may be null
   * @param tag  the String before and after the substring, may be null
   * @return the substring, <code>null</code> if no match
   * @since 2.0
   */
  public static String substringBetween(String str, String tag) {
      return substringBetween(str, tag, tag);
  }

  /**
   * Gets the String that is nested in between two Strings.
   * Only the first match is returned.
   *
   * A <code>null</code> input String returns <code>null</code>.
   * A <code>null</code> open/close returns <code>null</code> (no match).
   * An empty ("") open and close returns an empty string.
   *
   * <pre>
   * StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
   * StringUtils.substringBetween(null, *, *)          = null
   * StringUtils.substringBetween(*, null, *)          = null
   * StringUtils.substringBetween(*, *, null)          = null
   * StringUtils.substringBetween("", "", "")          = ""
   * StringUtils.substringBetween("", "", "]")         = null
   * StringUtils.substringBetween("", "[", "]")        = null
   * StringUtils.substringBetween("yabcz", "", "")     = ""
   * StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
   * StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
   * </pre>
   *
   * @param str  the String containing the substring, may be null
   * @param open  the String before the substring, may be null
   * @param close  the String after the substring, may be null
   * @return the substring, <code>null</code> if no match
   * @since 2.0
   */
  public static String substringBetween(String str, String open, String close) {
      if (str == null || open == null || close == null) {
          return null;
      }
      int start = str.indexOf(open);
      if (start != -1) {
          int end = str.indexOf(close, start + open.length());
          if (end != -1) {
              return str.substring(start + open.length(), end);
          }
      }
      return null;
  }

  // Empty checks
  //-----------------------------------------------------------------------
  /**
   * Checks if a String is empty ("") or null.
   *
   * <pre>
   * StringUtils.isEmpty(null)      = true
   * StringUtils.isEmpty("")        = true
   * StringUtils.isEmpty(" ")       = false
   * StringUtils.isEmpty("bob")     = false
   * StringUtils.isEmpty("  bob  ") = false
   * </pre>
   *
   * NOTE: This method changed in Lang version 2.0.
   * It no longer trims the String.
   * That functionality is available in isBlank().
   *
   * @param str  the String to check, may be null
   * @return <code>true</code> if the String is empty or null
   */
  public static boolean isEmpty(String str) {
      return str == null || str.length() == 0;
  }


}








2.34.Substring
2.34.1.Get the difference between two strings
2.34.2.Gets a substring from the specified String avoiding exceptions.
2.34.3.Gets len characters from the middle of a String.
2.34.4.Gets the String that is nested in between two Strings. Only the first match is returned.
2.34.5.Gets the String that is nested in between two instances of the same String.
2.34.6.Gets the leftmost len characters of a String
2.34.7.Gets the rightmost len characters of a String.
2.34.8.Gets the substring after the first occurrence of a separator. The separator is not returned.
2.34.9.Gets the substring before the last occurrence of a separator. The separator is not returned.
2.34.10.Removes a substring only if it is at the begining of a source string, otherwise returns the source string.
2.34.11.Removes a substring only if it is at the end of a source string, otherwise returns the source string.
2.34.12.Substitute sub-strings in side of a string
2.34.13.Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.
2.34.14.Counts how many times the substring appears in the larger String.
2.34.15.Count the number of instances of substring within a string