To add a list to another list at a specific location, here is the code
Add a list at the beginning
public static void main(String[] args) { // to make it modifiable using new List<Integer> list1 = new ArrayList<>(Arrays.asList(1,2, 3)); List<Integer> list2 = Arrays.asList(9,10, 11); List<Integer> list3 = new ArrayList<>(list1); list1.clear(); list1.addAll(list2); list1.addAll(list3); System.out.println(list1); }
Output
[9, 10, 11, 1, 2, 3]
Add a list at any index
public static void main(String[] args) { // to make it modifiable using new List<Integer> list1 = new ArrayList<>(Arrays.asList(1,2, 3)); List<Integer> list2 = Arrays.asList(9,10, 11); Collections.reverse(list2); for(Integer each:list2){ list1.add(0, each); } // reverse it back Collections.reverse(list2); System.out.println(list1); }
Output
[9, 10, 11, 1, 2, 3]