import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Demo { public static void main(String args[]) throws Exception { List<String>list = new ArrayList<String>(); list.add("A"); list.add("B"); list.add("C"); list = Collections.unmodifiableList(list); // An exception is thrown since its a read-only list now list.add("D"); list.add("E"); list.add("F"); System.out.println(list); } }