Java Iterable Join join(Iterator<?> iterator, String separator)

Description

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

No delimiter is added before or after the list.

License

Open Source License

Parameter

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

Return

the joined String, null if null iterator input

Declaration

public static String join(Iterator<?> iterator, String separator)

Method Source Code

//package com.java2s;
/**/*  www.java 2s . c o  m*/
 * <p>
 * Simple utility class for String operations useful across the framework.
 * <p/>
 * <p>
 * Some methods in this class were copied from the Spring Framework so we didn't
 * have to re-invent the wheel, and in these cases, we have retained all
 * license, copyright and author information.
 *
 * @since 0.9
 */

import java.util.*;

public class Main {
    /**
     * Constant representing the empty string, equal to &quot;&quot;
     */
    public static final String EMPTY_STRING = "";

    /**
     * Joins the elements of the provided {@code Iterator} into a single String
     * containing the provided elements.</p>
     * <p/>
     * No delimiter is added before or after the list. A {@code null} separator
     * is the same as an empty String ("").</p>
     * <p/>
     * Copied from Commons Lang, version 3 (r1138702).</p>
     *
     * @param iterator the {@code Iterator} of values to join together, may be
     * null
     * @param separator the separator character to use, null treated as ""
     * @return the joined String, {@code null} if null iterator input
     * @since 1.2
     */
    public static String join(Iterator<?> iterator, String separator) {
        final String empty = "";

        // handle null, zero and one elements before building a buffer
        if (iterator == null) {
            return null;
        }
        if (!iterator.hasNext()) {
            return empty;
        }
        Object first = iterator.next();
        if (!iterator.hasNext()) {
            return first == null ? empty : first.toString();
        }

        // two or more elements
        StringBuilder buf = new StringBuilder(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();
    }

    /**
     * Returns the specified array as a comma-delimited (',') string.
     *
     * @param array the array whose contents will be converted to a string.
     * @return the array's contents as a comma-delimited (',') string.
     * @since 1.0
     */
    public static String toString(Object[] array) {
        return toDelimitedString(array, ",");
    }

    /**
     * Returns the array's contents as a string, with each element delimited by
     * the specified {@code delimiter} argument. Useful for {@code toString()}
     * implementations and log messages.
     *
     * @param array the array whose contents will be converted to a string
     * @param delimiter the delimiter to use between each element
     * @return a single string, delimited by the specified {@code delimiter}.
     * @since 1.0
     */
    public static String toDelimitedString(Object[] array, String delimiter) {
        if (array == null || array.length == 0) {
            return EMPTY_STRING;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < array.length; i++) {
            if (i > 0) {
                sb.append(delimiter);
            }
            sb.append(array[i]);
        }
        return sb.toString();
    }

    /**
     * Returns the collection's contents as a string, with each element
     * delimited by the specified {@code delimiter} argument. Useful for
     * {@code toString()} implementations and log messages.
     *
     * @param c the collection whose contents will be converted to a string
     * @param delimiter the delimiter to use between each element
     * @return a single string, delimited by the specified {@code delimiter}.
     * @since 1.2
     */
    public static String toDelimitedString(Collection c, String delimiter) {
        if (c == null || c.isEmpty()) {
            return EMPTY_STRING;
        }
        return join(c.iterator(), delimiter);
    }
}

Java Iterable Join join(Iterator iterator, String separator)