List implementation based on array

ArrayList.java

package adt.list;
/**
 * List implementation based on Array.
 * 
 * @author Samuel T. C. Santos
 * @version 1.0
 * 
 * @param <E>
 */
public class ArrayList<E> implements List<E> {

	private E[] data;
	private int size = 0;
	private static final int CAPACITY = 5;
	
	public ArrayList(){
		this(CAPACITY);
	}
	
	@SuppressWarnings("unchecked")
	public ArrayList(int capacity){
		if (capacity <= 0){
			throw new IllegalArgumentException("Invalid Capacity!");
		}
		data = (E[]) new Object[capacity];
	}
	
	@Override
	public int size() {
		return size;
	}

	@Override
	public boolean isEmpty() {
		return size == 0;
	}

	@Override
	public E get(int i) throws IndexOutOfBoundsException {
		checkIndex(i, size);
		return data[i];
	}

	@Override
	public E set(int i, E element) 
			throws NullPointerException, IndexOutOfBoundsException {
		if (element == null) 
			throw new NullPointerException();
		
		checkIndex(i,size);
		E temp = data[i];
		data[i] = element;
		return temp;
	}

	@Override
	public void add(int i, E element) 
			throws NullPointerException, IndexOutOfBoundsException {
		if (element == null) 
			throw new NullPointerException();
		
		checkIndex(i, size+1);
		if (size == data.length){
			//throw new IllegalStateException("ArrayList is Full!");
			resize(2 * data.length);			
		}
		
		for (int k=size-1; k >= i; k--){
			data[k+1] = data[k];
		}
		data[i] = element;
		size++;
	}

	@Override
	public E remove(int i) throws IndexOutOfBoundsException {
		checkIndex(i, size);
		E temp = data[i];
		for (int k=i; k < size-1; k++){
			data[k] = data[k+1];
		}
		data[size-1] = null;
		size--;
		return temp;
	}
	
	/**
	* Resizes internal array to have given capacity >= size.
	*/
	protected void resize(int capacity){
		@SuppressWarnings("unchecked")
		E[] temp = (E[]) new Object[capacity];
		for (int k=0; k < size; k++){
			temp[k] = data[k];
		}
		data = temp;
	}


	/**
	 * Checks whether the given index is in the range [0, n-1].
	 * 
	 * @param i
	 * @param size
	 * @throws IndexOutOfBoundsException
	 */
	private void checkIndex(int i, int size) throws IndexOutOfBoundsException {
		if ( i < 0 || i > size){
			throw new IndexOutOfBoundsException("Invalid Index : " + i);
		}
	}

}