Here you can find the source of join(Collection c, String delim)
public static String join(Collection c, String delim)
//package com.java2s; /*//from w w w .j ava2 s . c o m StringUtils.java : A stand alone utility class. Copyright (C) 2000 Justin P. McCarthy This library 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 library 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 library; if not, see <http://www.gnu.org/licenses/>. To further contact the author please email jpmccar@gjt.org Modifications, copyright 2001-2014 Tuma Solutions, LLC; distributed under the LGPL, as described above. */ import java.util.Collection; import java.util.Iterator; public class Main { public static String join(Collection c, String delim) { if (c == null || c.isEmpty()) return ""; else if (c.size() == 1) return String.valueOf(c.iterator().next()); StringBuffer result = new StringBuffer(); for (Iterator i = c.iterator(); i.hasNext();) result.append(delim).append(i.next()); return result.substring(delim.length()); } }