Java Tutorial/Data Type/String Join

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Join an array of strings into one delimited string

/*
  * JBoss, Home of Professional Open Source
  * Copyright 2005, JBoss Inc., and individual contributors as indicated
  * by the @authors tag. See the copyright.txt in the distribution for a
  * full listing of individual contributors.
  *
  * This is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as
  * published by the Free Software Foundation; either version 2.1 of
  * the License, or (at your option) any later version.
  *
  * This software 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this software; if not, write to the Free
  * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
  */

public class Main{

  /////////////////////////////////////////////////////////////////////////
  //                    Joining/Concatenation Methods                    //
  /////////////////////////////////////////////////////////////////////////
  /**
   * Join an array of strings into one delimited string.
   *
   * @param buff    String buffered used for join (buffer is not reset).
   * @param array   Array of objects to join as strings.
   * @param delim   Delimiter to join strings with or <i>null</i>.
   * @return        Joined string.
   */
  public static String join(final StringBuffer buff, final Object array[],
     final String delim)
  {
     boolean haveDelim = (delim != null);
     for (int i = 0; i < array.length; i++)
     {
        buff.append(array[i]);
        // if this is the last element then don"t append delim
        if (haveDelim && (i + 1) < array.length)
        {
           buff.append(delim);
        }
     }
     return buff.toString();
  }
  /**
   * Join an array of strings into one delimited string.
   *
   * @param array   Array of objects to join as strings.
   * @param delim   Delimiter to join strings with or <i>null</i>.
   * @return        Joined string.
   */
  public static String join(final Object array[], final String delim)
  {
     return join(new StringBuffer(), array, delim);
  }
  /**
   * Convert and join an array of objects into one string.
   *
   * @param array   Array of objects to join as strings.
   * @return        Converted and joined objects.
   */
  public static String join(final Object array[])
  {
     return join(array, null);
  }
  /**
   * Convert and join an array of bytes into one string.
   *
   * @param array   Array of objects to join as strings.
   * @return        Converted and joined objects.
   */
  public static String join(final byte array[])
  {
     Byte bytes[] = new Byte[array.length];
     for (int i = 0; i < bytes.length; i++)
     {
        bytes[i] = new Byte(array[i]);
     }
     return join(bytes, null);
  }
  /**
   * Return a string composed of the given array.
   *
   * @param buff       Buffer used to construct string value (not reset).
   * @param array      Array of objects.
   * @param prefix     String prefix.
   * @param separator  Element sepearator.
   * @param suffix     String suffix.
   * @return           String in the format of:
   *                   prefix + n ( + separator + n+i)* + suffix.
   */
  public static String join(final StringBuffer buff, final Object[] array,
     final String prefix, final String separator,
     final String suffix)
  {
     buff.append(prefix);
     join(buff, array, separator);
     buff.append(suffix);
     return buff.toString();
  }
  /**
   * Return a string composed of the given array.
   *
   * @param array      Array of objects.
   * @param prefix     String prefix.
   * @param separator  Element sepearator.
   * @param suffix     String suffix.
   * @return           String in the format of:
   *                   prefix + n ( + separator + n+i)* + suffix.
   */
  public static String join(final Object[] array, final String prefix,
     final String separator, final String suffix)
  {
     return join(new StringBuffer(), array, prefix, separator, suffix);
  }

}





Joins array elements into a single String: specify the start index and end index.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)                = null
   * StringUtils.join([], *)                  = ""
   * StringUtils.join([null], *)              = ""
   * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
   * StringUtils.join(["a", "b", "c"], null)  = "abc"
   * StringUtils.join(["a", "b", "c"], "")    = "abc"
   * StringUtils.join([null, "", "a"], ",")   = ",,a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @param startIndex the first index to start joining from.  It is
   * an error to pass in an end index past the end of the array
   * @param endIndex the index to stop joining from (exclusive). It is
   * an error to pass in an end index past the end of the array
   * @return the joined String, <code>null</code> if null array input
   */
  public static String join(Object[] array, String separator, int startIndex, int endIndex) {
      if (array == null) {
          return null;
      }
      if (separator == null) {
          separator = "";
      }
      // endIndex - startIndex > 0:   Len = NofStrings *(len(firstString) + len(separator))
      //           (Assuming that all Strings are roughly equally long)
      int bufSize = (endIndex - startIndex);
      if (bufSize <= 0) {
          return "";
      }
      bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
                      + separator.length());
      StringBuffer buf = new StringBuffer(bufSize);
      for (int i = startIndex; i < endIndex; i++) {
          if (i > startIndex) {
              buf.append(separator);
          }
          if (array[i] != null) {
              buf.append(array[i]);
          }
      }
      return buf.toString();
  }
}





Joins array elements into a single String without specifying the start index and end index.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)                = null
   * StringUtils.join([], *)                  = ""
   * StringUtils.join([null], *)              = ""
   * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
   * StringUtils.join(["a", "b", "c"], null)  = "abc"
   * StringUtils.join(["a", "b", "c"], "")    = "abc"
   * StringUtils.join([null, "", "a"], ",")   = ",,a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @return the joined String, <code>null</code> if null array input
   */
  public static String join(Object[] array, String separator) {
      if (array == null) {
          return null;
      }
      return join(array, separator, 0, array.length);
  }
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)                = null
   * StringUtils.join([], *)                  = ""
   * StringUtils.join([null], *)              = ""
   * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
   * StringUtils.join(["a", "b", "c"], null)  = "abc"
   * StringUtils.join(["a", "b", "c"], "")    = "abc"
   * StringUtils.join([null, "", "a"], ",")   = ",,a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @param startIndex the first index to start joining from.  It is
   * an error to pass in an end index past the end of the array
   * @param endIndex the index to stop joining from (exclusive). It is
   * an error to pass in an end index past the end of the array
   * @return the joined String, <code>null</code> if null array input
   */
  public static String join(Object[] array, String separator, int startIndex, int endIndex) {
      if (array == null) {
          return null;
      }
      if (separator == null) {
          separator = "";
      }
      // endIndex - startIndex > 0:   Len = NofStrings *(len(firstString) + len(separator))
      //           (Assuming that all Strings are roughly equally long)
      int bufSize = (endIndex - startIndex);
      if (bufSize <= 0) {
          return "";
      }
      bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
                      + separator.length());
      StringBuffer buf = new StringBuffer(bufSize);
      for (int i = startIndex; i < endIndex; i++) {
          if (i > startIndex) {
              buf.append(separator);
          }
          if (array[i] != null) {
              buf.append(array[i]);
          }
      }
      return buf.toString();
  }
}





Joins array elements: Null objects or empty strings within the array are represented by empty strings.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No separator is added to the joined String.
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null)            = null
   * StringUtils.join([])              = ""
   * StringUtils.join([null])          = ""
   * StringUtils.join(["a", "b", "c"]) = "abc"
   * StringUtils.join([null, "", "a"]) = "a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @return the joined String, <code>null</code> if null array input
   * @since 2.0
   */
  public static String join(Object[] array) {
      return join(array, null);
  }
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)                = null
   * StringUtils.join([], *)                  = ""
   * StringUtils.join([null], *)              = ""
   * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
   * StringUtils.join(["a", "b", "c"], null)  = "abc"
   * StringUtils.join(["a", "b", "c"], "")    = "abc"
   * StringUtils.join([null, "", "a"], ",")   = ",,a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @return the joined String, <code>null</code> if null array input
   */
  public static String join(Object[] array, String separator) {
      if (array == null) {
          return null;
      }
      return join(array, separator, 0, array.length);
  }
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)                = null
   * StringUtils.join([], *)                  = ""
   * StringUtils.join([null], *)              = ""
   * StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
   * StringUtils.join(["a", "b", "c"], null)  = "abc"
   * StringUtils.join(["a", "b", "c"], "")    = "abc"
   * StringUtils.join([null, "", "a"], ",")   = ",,a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @param startIndex the first index to start joining from.  It is
   * an error to pass in an end index past the end of the array
   * @param endIndex the index to stop joining from (exclusive). It is
   * an error to pass in an end index past the end of the array
   * @return the joined String, <code>null</code> if null array input
   */
  public static String join(Object[] array, String separator, int startIndex, int endIndex) {
      if (array == null) {
          return null;
      }
      if (separator == null) {
          separator = "";
      }
      // endIndex - startIndex > 0:   Len = NofStrings *(len(firstString) + len(separator))
      //           (Assuming that all Strings are roughly equally long)
      int bufSize = (endIndex - startIndex);
      if (bufSize <= 0) {
          return "";
      }
      bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length())
                      + separator.length());
      StringBuffer buf = new StringBuffer(bufSize);
      for (int i = startIndex; i < endIndex; i++) {
          if (i > startIndex) {
              buf.append(separator);
          }
          if (array[i] != null) {
              buf.append(array[i]);
          }
      }
      return buf.toString();
  }
}





Joins the elements of Collection into a single String with string separator.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided <code>Collection</code> into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   *
   * See the examples here: {@link #join(Object[],String)}. 
   *
   * @param collection  the <code>Collection</code> of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @return the joined String, <code>null</code> if null iterator input
   * @since 2.3
   */
  public static String join(Collection collection, String separator) {
      if (collection == null) {
          return null;
      }
      return join(collection.iterator(), separator);
  }
  /**
   * Joins the elements of the provided <code>Iterator</code> into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   *
   * See the examples here: {@link #join(Object[],String)}. 
   *
   * @param iterator  the <code>Iterator</code> of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @return the joined String, <code>null</code> if null iterator input
   */
  public static String join(Iterator iterator, String separator) {
      // handle null, zero and one elements before building a buffer
      if (iterator == null) {
          return null;
      }
      if (!iterator.hasNext()) {
          return "";
      }
      Object first = iterator.next();
      if (!iterator.hasNext()) {
          return toString(first);
      }
      // two or more elements
      StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
      if (first != null) {
          buf.append(first);
      }
      while (iterator.hasNext()) {
          if (separator != null) {
              buf.append(separator);
          }
          Object obj = iterator.next();
          if (obj != null) {
              buf.append(obj);
          }
      }
      return buf.toString();
  }
  // ToString
  //-----------------------------------------------------------------------
  /**
   * Gets the <code>toString</code> of an <code>Object</code> returning
   * an empty string ("") if <code>null</code> input.
   * 
   * <pre>
   * ObjectUtils.toString(null)         = ""
   * ObjectUtils.toString("")           = ""
   * ObjectUtils.toString("bat")        = "bat"
   * ObjectUtils.toString(Boolean.TRUE) = "true"
   * </pre>
   * 
   * @see StringUtils#defaultString(String)
   * @see String#valueOf(Object)
   * @param obj  the Object to <code>toString</code>, may be null
   * @return the passed in Object"s toString, or nullStr if <code>null</code> input
   * @since 2.0
   */
  public static String toString(Object obj) {
      return obj == null ? "" : obj.toString();
  }
}





Joins the elements of the provided array into a single String containing the provided list of elements.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)               = null
   * StringUtils.join([], *)                 = ""
   * StringUtils.join([null], *)             = ""
   * StringUtils.join(["a", "b", "c"], ";")  = "a;b;c"
   * StringUtils.join(["a", "b", "c"], null) = "abc"
   * StringUtils.join([null, "", "a"], ";")  = ";;a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use
   * @return the joined String, <code>null</code> if null array input
   * @since 2.0
   */
  public static String join(Object[] array, char separator) {
      if (array == null) {
          return null;
      }
      return join(array, separator, 0, array.length);
  }
  /**
   * Joins the elements of the provided array into a single String
   * containing the provided list of elements.
   *
   * No delimiter is added before or after the list.
   * Null objects or empty strings within the array are represented by
   * empty strings.
   *
   * <pre>
   * StringUtils.join(null, *)               = null
   * StringUtils.join([], *)                 = ""
   * StringUtils.join([null], *)             = ""
   * StringUtils.join(["a", "b", "c"], ";")  = "a;b;c"
   * StringUtils.join(["a", "b", "c"], null) = "abc"
   * StringUtils.join([null, "", "a"], ";")  = ";;a"
   * </pre>
   *
   * @param array  the array of values to join together, may be null
   * @param separator  the separator character to use
   * @param startIndex the first index to start joining from.  It is
   * an error to pass in an end index past the end of the array
   * @param endIndex the index to stop joining from (exclusive). It is
   * an error to pass in an end index past the end of the array
   * @return the joined String, <code>null</code> if null array input
   * @since 2.0
   */
  public static String join(Object[] array, char separator, int startIndex, int endIndex) {
      if (array == null) {
          return null;
      }
      int bufSize = (endIndex - startIndex);
      if (bufSize <= 0) {
          return "";
      }
      bufSize *= ((array[startIndex] == null ? 16 : array[startIndex].toString().length()) + 1);
      StringBuffer buf = new StringBuffer(bufSize);
      for (int i = startIndex; i < endIndex; i++) {
          if (i > startIndex) {
              buf.append(separator);
          }
          if (array[i] != null) {
              buf.append(array[i]);
          }
      }
      return buf.toString();
  }
}





Joins the elements of the provided Collection into a single String containing the provided elements.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided <code>Collection</code> into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list. Null objects or empty
   * strings within the iteration are represented by empty strings.
   *
   * See the examples here: {@link #join(Object[],char)}. 
   *
   * @param collection  the <code>Collection</code> of values to join together, may be null
   * @param separator  the separator character to use
   * @return the joined String, <code>null</code> if null iterator input
   * @since 2.3
   */
  public static String join(Collection collection, char separator) {
      if (collection == null) {
          return null;
      }
      return join(collection.iterator(), separator);
  }
  /**
   * Joins the elements of the provided <code>Iterator</code> into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list. Null objects or empty
   * strings within the iteration are represented by empty strings.
   *
   * See the examples here: {@link #join(Object[],char)}. 
   *
   * @param iterator  the <code>Iterator</code> of values to join together, may be null
   * @param separator  the separator character to use
   * @return the joined String, <code>null</code> if null iterator input
   * @since 2.0
   */
  public static String join(Iterator iterator, char separator) {
      // handle null, zero and one elements before building a buffer
      if (iterator == null) {
          return null;
      }
      if (!iterator.hasNext()) {
          return "";
      }
      Object first = iterator.next();
      if (!iterator.hasNext()) {
          return toString(first);
      }
      // two or more elements
      StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
      if (first != null) {
          buf.append(first);
      }
      while (iterator.hasNext()) {
          buf.append(separator);
          Object obj = iterator.next();
          if (obj != null) {
              buf.append(obj);
          }
      }
      return buf.toString();
  }
  // ToString
  //-----------------------------------------------------------------------
  /**
   * Gets the <code>toString</code> of an <code>Object</code> returning
   * an empty string ("") if <code>null</code> input.
   * 
   * <pre>
   * ObjectUtils.toString(null)         = ""
   * ObjectUtils.toString("")           = ""
   * ObjectUtils.toString("bat")        = "bat"
   * ObjectUtils.toString(Boolean.TRUE) = "true"
   * </pre>
   * 
   * @see StringUtils#defaultString(String)
   * @see String#valueOf(Object)
   * @param obj  the Object to <code>toString</code>, may be null
   * @return the passed in Object"s toString, or nullStr if <code>null</code> input
   * @since 2.0
   */
  public static String toString(Object obj) {
      return obj == null ? "" : obj.toString();
  }
}





Joins the elements of the provided Iterator into a single String containing the provided elements.

/*
 * 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.
 */
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class Main {
  /**
   * Joins the elements of the provided <code>Iterator</code> into
   * a single String containing the provided elements.
   *
   * No delimiter is added before or after the list.
   * A <code>null</code> separator is the same as an empty String ("").
   *
   * See the examples here: {@link #join(Object[],String)}. 
   *
   * @param iterator  the <code>Iterator</code> of values to join together, may be null
   * @param separator  the separator character to use, null treated as ""
   * @return the joined String, <code>null</code> if null iterator input
   */
  public static String join(Iterator iterator, String separator) {
      // handle null, zero and one elements before building a buffer
      if (iterator == null) {
          return null;
      }
      if (!iterator.hasNext()) {
          return "";
      }
      Object first = iterator.next();
      if (!iterator.hasNext()) {
          return toString(first);
      }
      // two or more elements
      StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
      if (first != null) {
          buf.append(first);
      }
      while (iterator.hasNext()) {
          if (separator != null) {
              buf.append(separator);
          }
          Object obj = iterator.next();
          if (obj != null) {
              buf.append(obj);
          }
      }
      return buf.toString();
  }
  // ToString
  //-----------------------------------------------------------------------
  /**
   * Gets the <code>toString</code> of an <code>Object</code> returning
   * an empty string ("") if <code>null</code> input.
   * 
   * <pre>
   * ObjectUtils.toString(null)         = ""
   * ObjectUtils.toString("")           = ""
   * ObjectUtils.toString("bat")        = "bat"
   * ObjectUtils.toString(Boolean.TRUE) = "true"
   * </pre>
   * 
   * @see StringUtils#defaultString(String)
   * @see String#valueOf(Object)
   * @param obj  the Object to <code>toString</code>, may be null
   * @return the passed in Object"s toString, or nullStr if <code>null</code> input
   * @since 2.0
   */
  public static String toString(Object obj) {
      return obj == null ? "" : obj.toString();
  }
}





Join String

/*
 * Static String formatting and query routines.
 * Copyright (C) 2001-2005 Stephen Ostermiller
 * http://ostermiller.org/contact.pl?regarding=Java+Utilities
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * See COPYING.TXT for details.
 */

import java.util.HashMap;
import java.util.regex.Pattern;
/**
 * Utilities for String formatting, manipulation, and queries.
 * More information about this class is available from .
 *
 * @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
 * @since ostermillerutils 1.00.00
 */
public class StringHelper {
  /**
   * Join all the elements of a string array into a single
   * String.
   * 
   * If the given array empty an empty string
   * will be returned.  Null elements of the array are allowed
   * and will be treated like empty Strings.
   *
   * @param array Array to be joined into a string.
   * @return Concatenation of all the elements of the given array.
   * @throws NullPointerException if array is null.
   *
   * @since ostermillerutils 1.05.00
   */
  public static String join(String[] array){
    return join(array, "");
  }
  /**
   * Join all the elements of a string array into a single
   * String.
   * 
   * If the given array empty an empty string
   * will be returned.  Null elements of the array are allowed
   * and will be treated like empty Strings.
   *
   * @param array Array to be joined into a string.
   * @param delimiter String to place between array elements.
   * @return Concatenation of all the elements of the given array with the the delimiter in between.
   * @throws NullPointerException if array or delimiter is null.
   *
   * @since ostermillerutils 1.05.00
   */
  public static String join(String[] array, String delimiter){
    // Cache the length of the delimiter
    // has the side effect of throwing a NullPointerException if
    // the delimiter is null.
    int delimiterLength = delimiter.length();
    // Nothing in the array return empty string
    // has the side effect of throwing a NullPointerException if
    // the array is null.
    if (array.length == 0) return "";
    // Only one thing in the array, return it.
    if (array.length == 1){
      if (array[0] == null) return "";
      return array[0];
    }
    // Make a pass through and determine the size
    // of the resulting string.
    int length = 0;
    for (int i=0; i<array.length; i++){
      if (array[i] != null) length+=array[i].length();
      if (i<array.length-1) length+=delimiterLength;
    }
    // Make a second pass through and concatenate everything
    // into a string buffer.
    StringBuffer result = new StringBuffer(length);
    for (int i=0; i<array.length; i++){
      if (array[i] != null) result.append(array[i]);
      if (i<array.length-1) result.append(delimiter);
    }
    return result.toString();
  }

}





Join string from soapUI

/*
 *  soapUI, copyright (C) 2004-2009 eviware.ru 
 *
 *  soapUI is free software; you can redistribute it and/or modify it under the 
 *  terms of version 2.1 of the GNU Lesser General Public License as published by 
 *  the Free Software Foundation.
 *
 *  soapUI 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 Lesser General Public License for more details at gnu.org.
 */

public class Utils {
  
  public static String join( String[] array, String separator )
  {
    StringBuffer buf = new StringBuffer();
    for( int i = 0; i < array.length; i++ )
    {
      if( i > 0 )
        buf.append( separator );
      buf.append( array[i] );
    }
    return buf.toString();
  }
}





Overlays part of a String with another String.

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
/* 
 * 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 {
  /**
   * Overlays part of a String with another String.
   *
   * A <code>null</code> string input returns <code>null</code>.
   * A negative index is treated as zero.
   * An index greater than the string length is treated as the string length.
   * The start index is always the smaller of the two indices.
   *
   * <pre>
   * StringUtils.overlay(null, *, *, *)            = null
   * StringUtils.overlay("", "abc", 0, 0)          = "abc"
   * StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
   * StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
   * StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
   * StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
   * StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
   * StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
   * StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
   * StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
   * StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"
   * </pre>
   *
   * @param str  the String to do overlaying in, may be null
   * @param overlay  the String to overlay, may be null
   * @param start  the position to start overlaying at
   * @param end  the position to stop overlaying before
   * @return overlayed String, <code>null</code> if null String input
   * @since 2.0
   */
  public static String overlay(String str, String overlay, int start, int end) {
      if (str == null) {
          return null;
      }
      if (overlay == null) {
          overlay = "";
      }
      int len = str.length();
      if (start < 0) {
          start = 0;
      }
      if (start > len) {
          start = len;
      }
      if (end < 0) {
          end = 0;
      }
      if (end > len) {
          end = len;
      }
      if (start > end) {
          int temp = start;
          start = end;
          end = temp;
      }
      return new StringBuffer(len + start - end + overlay.length() + 1)
          .append(str.substring(0, start))
          .append(overlay)
          .append(str.substring(end))
          .toString();
  }
}