i know how to add many things into arraylist at once, like:

String [] things = {"eggs ", "pie ", "lasers ", "hat "};
        List<String> list1 = new ArrayList<String>();

        for (String x: things)
            list1.add(x);

but is there a way to add things into arraylist iteratively one by one?

If the things are in any kind of Collection you can use addAll(Collection c),
If it''s an array you can use Arrays.toList(...) to convert the array to a List that you can pass to addAll

but is there a way to add things into arraylist iteratively one by one?

That is exactly what your code is doing!