Here you can find the source of concat(String[]... arrays)
public static List<String> concat(String[]... arrays)
//package com.java2s; //License from project: Open Source License import java.util.*; public class Main { public static List<String> concat(String[]... arrays) { List<String> result = new ArrayList<String>(); for (String[] p : arrays) { for (String x : p) { result.add(x);//from w w w . jav a 2 s . co m } } return result; } }