Here you can find the source of join(final Collection collection, String delimiter)
public static String join(final Collection collection, String delimiter)
//package com.java2s; /**//from w ww .j a v a 2 s .co m * Copyright (C) 2016 Hurence (support@hurence.com) * * 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.Collection; public class Main { public static final String EMPTY = ""; public static String join(final Collection collection, String delimiter) { if (collection == null || collection.size() == 0) { return EMPTY; } final StringBuilder sb = new StringBuilder(collection.size() * 16); for (Object element : collection) { sb.append((String) element); sb.append(delimiter); } return sb.toString().substring(0, sb.lastIndexOf(delimiter)); } }