// Simple example of using an interface to write general code that can be
// applied to two types of objects that both implement an interface known as
// IntList.

public class ListClient {
    public static void main(String[] args) {
        IntList list1 = new ArrayIntList();
        processList(list1);

        IntList list2 = new LinkedIntList();
        processList(list2);

        // error to say:
        // IntList list3 = new IntList();
    }

    // do some basic manipulations with a list
    public static void processList(IntList list) {
        list.add(18);
        list.add(27);
        list.add(93);
        System.out.println(list);
        list.remove(1);
        System.out.println(list);
    }
}