Here you can find the source of join(CharSequence delimiter, Iterable extends CharSequence> elements)
public static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements)
//package com.java2s; /*//from ww w . ja v a 2s . c o m * Copyright (C) 2015 the original author or authors. * * 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 String join(CharSequence delimiter, Iterable<? extends CharSequence> elements) { if (delimiter == null) { delimiter = ""; } StringBuilder buffer = new StringBuilder(); Iterator<? extends CharSequence> it = elements.iterator(); while (it.hasNext()) { buffer.append(it.next()); if (it.hasNext()) { buffer.append(delimiter); } } return buffer.toString(); } }