Here you can find the source of insertBefore(List
public static <E> void insertBefore(List<E> list, E... elements)
//package com.java2s; //License from project: Apache License import java.util.List; import java.util.ListIterator; public class Main { public static <E> void insertBefore(List<E> list, E... elements) { if (list != null) { ListIterator<E> iIterator = list.listIterator(); for (E newElement : elements) { iIterator.add(newElement); }//from ww w.j a v a 2 s.co m } } }