How to concat two ArrayLists?

Question

I have two ArrayLists of equal size. List 1 consists of 10 names and list 2 consists of their phone numbers.

I want to concat the names and number into

Answer 1

If you want to do it one line and you do not want to change list1 or list2 you can do it using stream

List list1 = Arrays.asList("London", "Paris");
List list2 = Arrays.asList("Moscow", "Tver");

List list = Stream.concat(list1.stream(),list2.stream()).collect(Collectors.toList());