Here you can find the source of join(Object[] elements, CharSequence separator)
public static String join(Object[] elements, CharSequence separator)
//package com.java2s; /*//from w w w . jav a 2s.co m * Copyright (C) 2012 YIXIA.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.Arrays; import java.util.Iterator; public class Main { public static String join(Object[] elements, CharSequence separator) { return join(Arrays.asList(elements), separator); } public static String join(Iterable<? extends Object> elements, CharSequence separator) { StringBuilder builder = new StringBuilder(); if (elements != null) { Iterator<? extends Object> iter = elements.iterator(); if (iter.hasNext()) { builder.append(String.valueOf(iter.next())); while (iter.hasNext()) { builder.append(separator).append(String.valueOf(iter.next())); } } } return builder.toString(); } }