StringHelper.java

package com.opentrust.spi.helpers;

import java.util.Iterator;

public class StringHelper {
    /**
     * <p>Joins the elements of the provided <code>Iterator</code> into
     * a single String containing the provided elements.</p>
     *
     * <p>No delimiter is added before or after the list.
     * A <code>null</code> separator is the same as an empty String ("").</p>
     *
     * <p>See the examples here: {@link #join(Object[],String)}. </p>
     *
     * @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 first == null ? "" : first.toString();
        }

        // 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();
    }
}