Here you can find the source of join(String separator, List
public static String join(String separator, List<String> parts)
//package com.java2s; /*/*from w w w .j a va 2 s . com*/ * Copyright (C) 2018 Inera AB (http://www.inera.se) * * This file is part of sklintyg (https://github.com/sklintyg). * * sklintyg 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 3 of the License, or * (at your option) any later version. * * sklintyg 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. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ import java.util.Arrays; import java.util.List; public class Main { public static String join(String separator, List<String> parts) { StringBuilder result = new StringBuilder(); for (String part : parts) { if (!isNullOrEmpty(part)) { if (result.length() > 0) { result.append(separator); } result.append(part); } } return result.toString(); } public static String join(String separator, String... parts) { return join(separator, Arrays.asList(parts)); } /** Returns true if string is null or ahs length 0, otherwise false. */ public static boolean isNullOrEmpty(String string) { return string == null || string.length() == 0; } }