public class CustomArrayList
		{

		    private Object[] arr;

		    private int count;

		    private static final int INITIAL_CAPACITY = 4;



		    /** Initializes the array-based list – allocate memory **/

		    public CustomArrayList()
		    {

		        arr = new Object[INITIAL_CAPACITY];

		        count = 0;

		    }



		    /**

		     * @return the actual list length

		     */

		    public int getLength()
		    {

		        return count;
		    }


		        public void add(Object item)
		        {

		            add(count, item);

		        }



		        /**

		         * Inserts the specified element at given position in this list

		         * @param index -

		         *        index at which the specified element is to be inserted

		         * @param item -

		         *        element to be inserted

		         * @throws IndexOutOfBoundsException

		         */

		        public void add(int index, Object item)
		        {

		            if (index>count || index<0) {

		                throw new IndexOutOfBoundsException(

		                    "Invalid index: " + index);

		            }

		            Object[] extendedArr = arr;

		            if (count + 1 == arr.length) {

		                extendedArr = new Object[arr.length * 2];

		            }



		            System.arraycopy(arr, 0, extendedArr, 0, index);

		            count++;

		            System.arraycopy(

		                arr, index, extendedArr, index+1, count-index-1);

		            extendedArr[index] = item;

		            arr = extendedArr;

		        }/**

 * Returns the index of the first occurrence of the specified

 * element in this list.

 *

 * @param item - the element you are searching

 * @return the index of given element or -1 is not found

 */

public int indexOf(Object item) {

    if (item == null) {

        for (int i = 0; i < arr.length; i++) {

            if (arr[i] == null)

                return i;

        }

    } else {

        for (int i = 0; i < arr.length; i++)

            if (item.equals(arr[i]))

                return i;

    }

    return -1;

}



/**

 * Clears the list

 */

    public void clear() {

    arr = new Object[0];

    count = 0;

}



/**

 * Checks if an element exists

 * @param item – the item to be checked

 * @return if the item exists

 */

public boolean contains(Object item) {

    int index = indexOf(item);

    boolean found = (index != -1);

    return found;

}



/**

 * @return the object on given position

 */

public Object elementAt(int index) {

    if (index>=count || index<0) {

        throw new IndexOutOfBoundsException(

            "Invalid index: " + index);

    }

    return arr[index];

}/**

 * Removes the element at the specified index

 * @param index - the index, whose element you want to remove

 * @return the removed element

 */

public Object remove(int index)
{

    if (index>=count || index<0) {

        throw new IndexOutOfBoundsException(

            "Invalid index: " + index);

    }

    Object item = arr[index];

    System.arraycopy(arr, index+1, arr, index, count-index+1);

    arr[count - 1] = null;

    count--;

    return item;

}



/**

 * Removes the specified item and returns its index or -1

 * if item does not exists

 * @param item - the item you want to remove

*/

public int remove(Object item)
{

    int index = indexOf(item);

    if (index == -1) {

        return index;

    }

    System.arraycopy(arr, index+1, arr, index, count-index+1);

    count--;

    return index;

}



public static void main(String[] args)
{

    CustomArrayList shoppingList = new CustomArrayList();

    shoppingList.add("Milk");

    shoppingList.add("Honey");

    shoppingList.add("Olives");

    shoppingList.add("Beer");

    shoppingList.remove("Olives");

    System.out.println("We need to buy:");

    for(int i=0; i<shoppingList.getLength(); i++) {

        System.out.println(shoppingList.elementAt(i));

    }

    System.out.println("Do we have to buy Bread? " +

        shoppingList.contains("Bread"));

}


}