Here you can find the source of concat(List lista, List listb)
private static <A> List<A> concat(List<A> lista, List<A> listb)
//package com.java2s; //License from project: Open Source License import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Main { private static <A> List<A> concat(List<A> lista, List<A> listb) { List<A> result = new ArrayList<>(lista); result.addAll(listb);/*from www . j ava2s . c o m*/ return Collections.unmodifiableList(result); } }