Can we nest arraylist?

Question

Can we nest arraylist? if yes can any one give me an example of it?

Answer 1

ArrayList<ArrayList<String>> all = new ArrayList<>();

ArrayList<String> al = new ArrayList<>();
al.add("a");
all.add(al);

ArrayList<String> al2 = new ArrayList<>();
al2.add("b1");
al2.add("b2");
all.add(al2);

System.out.println(all);