Java Array Join join(Object[] array, String separator)

Description

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.

License

Apache License

Parameter

Parameter	Description
array	the array of values to join together, may be null
separator	the separator character to use, null treated as ""

Return

the joined String, null if null array input

Declaration

public static String join(Object[] array, String separator)

Method Source Code

//package com.java2s;
/*//from   w w  w .j  ava2s.  c  om
 * Copyright 2014 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed 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.Collection;
import java.util.Iterator;

public class Main {
    /**
     * <p>Joins the elements of the provided array into a single String
     * containing the provided list of elements.</p>
     *
     * <p>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.</p>
     *
     * <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;
        }
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < array.length; i++) {
            Object o = array[i];
            if (i > 0) {
                builder.append(separator);
            }
            builder.append(o);
        }
        return builder.toString();
    }

    /**
     * Joins a collection of string with a given delimiter.
     *
     * @param strings The collection of strings to join.
     * @param delimiter The delimiter to use to join them.
     * @return The string built by joining the string with the delimiter.
     */
    public static String join(Collection strings, String delimiter) {
        StringBuilder builder = new StringBuilder();
        Iterator<String> iter = strings.iterator();
        while (iter.hasNext()) {
            builder.append(iter.next());
            if (!iter.hasNext()) {
                break;
            }
            builder.append(delimiter);
        }
        return builder.toString();
    }
}