Java Generic class doesn't display the objects i pass into it

Question

I am trying to build a simple generic class that uses generic objects in java. everything compiles fine, but when i run the code, it doesn't display the objects i passed to it.

Here is my code:

public class ListDriver {


    public static void main(String[] args) {

        List<String> glist = new List<String>(10);

        glist.add("milk");
        glist.add("eggs");
        System.out.println("Grocery List" + glist.toString());

    }


    public class List<T> {
        private T[] datastore;
        private int size;
        private int pos;


        public List(int numElements) {
            size = numElements;
            pos = 0;
            datastore = (T[]) new Object[size];
        }

        public void add(T element) {
            datastore[pos] = element;

        }

        public String toString() {
            String elements = "";
            for (int i = 0; i < pos; ++i) {
                elements += datastore[i] + "";
            }
            return elements;
        }

    }
}

Answer 1

You don't increment your pos variable, so you're always adding in the same place. Try

public void add(T element) {
        datastore[pos++] = element;

    }

Answer 2

Your add method always replaces the element in position 0 (zero). You forgot to increment pos (pos++;)