Collection.sort does not work for my Array

I created my own MyArrayList but it can not be sorted. A normal Arraylist can be sorted by Collections.sort but mine can not. Could some one tell me where is wrong?

import java.util.*;

public class TestMyArrayList
{
    public static void main(String[] args){
        String[] subjects = {"EIE320", "EIE558", "EIE375", "EIE424"};
        Integer[] marks = {90,85,70,80};
        MyArrayList<String> sList = new MyArrayList<String>(subjects);
        Collections.sort(sList);
        sList.print();
        MyArrayList<Integer> mList = new MyArrayList<Integer>(marks);
        Collections.sort(mList);
        mList.print();
    }
}

public class MyArrayList<E> extends ArrayList<E>
    implements List<E>
{    
    private List<E> data;

    public MyArrayList()
    {
    }

    public MyArrayList(E[] inputdata){
        super();
        data = new ArrayList<E>();
        for(E e:inputdata){
            data.add(e);
        }
    }

    public void print(){
        for(Iterator iter = data.iterator();iter.hasNext();){
            System.out.print(iter.next() + " ");
        }

        System.out.println(" ");
    }
}