Here you can find the source of join(Iterable
public static <T> String join(Iterable<T> iterable)
//package com.java2s; /*/* ww w. j ava 2 s .com*/ * Copyright 2011 France Telecom R&D Beijing Co., Ltd ??????????????????? * * Licensed 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.Iterator; public class Main { public static <T> String join(Iterable<T> iterable) { Iterator<T> iterator = iterable.iterator(); if (!iterator.hasNext()) { return ""; } StringBuilder stringBuilder = new StringBuilder(iterator.next().toString()); while (iterator.hasNext()) { stringBuilder.append(","); stringBuilder.append(iterator.next().toString()); } return stringBuilder.toString(); } }