Here you can find the source of copy(List
public static <T> List<T> copy(List<T> list)
//package com.java2s; //License from project: Apache License import java.util.*; public class Main { public static <T> List<T> copy(List<T> list) { if (list == null) { return null; }//ww w. j a va2 s . c om List<T> copys = new ArrayList<T>(list.size()); for (T t : list) { copys.add(t); } return copys; } }