Here you can find the source of join(List
public static <X> List<X> join(List<X>... elements)
//package com.java2s; /*// ww w. j av a2 s. c o m * Copyright 2012 gitblit.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.ArrayList; import java.util.Arrays; import java.util.List; public class Main { public static <X> List<X> join(List<X>... elements) { List<X> list = new ArrayList<X>(); for (List<X> element : elements) { list.addAll(element); } return list; } public static <X> List<X> join(X[]... elements) { List<X> list = new ArrayList<X>(); for (X[] element : elements) { list.addAll(Arrays.asList(element)); } return list; } }