Here you can find the source of join(String delim, Collection
public static String join(String delim, Collection<String> values)
//package com.java2s; /**// w ww.j av a 2s. com * Licensed to the Apache Software Foundation (ASF) under one or more contributor license * agreements. See the NOTICE file distributed with this work for additional information regarding * copyright ownership. The ASF licenses this file to you 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; public class Main { public static String join(String delim, String... values) { if (values == null || values.length == 0) { return ""; } StringBuilder s = new StringBuilder(); for (String v : values) { s.append(delim); s.append(v); } return s.toString().substring(delim.length()); } public static String join(String delim, Collection<String> values) { if (values == null || values.size() == 0) { return ""; } StringBuilder s = new StringBuilder(); for (String v : values) { s.append(delim); s.append(v); } return s.toString().substring(delim.length()); } }