public class ArrayList implements List {

	private String[] elements;

	private int currPosition = 0;

	public ArrayList() {
		elements = new String[20];

	}

	private void exchange() {

		String temp;

		for (int i = currPosition + 1; i < elements.length; i++) {

			if (elements[i] == null) {
				currPosition = i - 1;
				break;
			}
			temp = elements[i];
			elements[i] = null;
			elements[i - 1] = temp;
			if (i == elements.length - 1) {
				currPosition = i;
				break;
			}
		}

	}

	private void enlargeArray() {

		String[] temp = new String[elements.length + 20];

		for (int i = 0; i < elements.length; i++) {
			temp[i] = elements[i];
		}

		elements = temp;
	}

	public void add(String element) {

		if (currPosition > elements.length) {
			enlargeArray();
		}

		elements[currPosition] = element;
		currPosition++;
	}

	public void clear() {
		elements = new String[20];
		currPosition = 0;

	}

	public boolean contains(String element) {

		for (int i = 0; i < currPosition; i++) {

			if (elements[i].equals(element)) {
				return true;
			}

		}

		return false;
	}

	public ListIterator getIterator() {

		ArrayListIterator iterator = new ArrayListIterator();

		return iterator;
	}

	public int getSize() {
		return currPosition;
	}

	public int indexOf(String element) {

		for (int i = 0; i < currPosition; i++) {

			if (elements[i].equals(element)) {
				return i;

			}
		}

		return -1;
	}

	public void insert(String element, int index) {

		if (index <= currPosition) {
			elements[index] = element;
		}

	}

	public boolean isEmpty() {

		if (currPosition == 0 && elements[0] == null) {
			return true;
		}

		return false;
	}

	public void remove(String element) {

		for (int i = 0; i < currPosition; i++) {

			if (elements[i].equals(element)) {
				elements[i] = null;

				if (currPosition - 1 > i) {

					currPosition = i;
					exchange();
					return;
				} else {
					currPosition = i;
					return;
				}

			}

		}
	}

	public void removeElementAt(int index) {

		if (index < currPosition) {

			elements[index] = null;

			if (index == currPosition - 1) {

				currPosition = index;

			} else {
				exchange();
			}
		}

	}

	public class ArrayListIterator implements ListIterator {

		private int currIndex = 0;

		public boolean hasNext() {

			if (currIndex + 1 <= currPosition) {
				return true;
			}

			return false;
		}

		public String next() {
			currIndex++;

			return elements[currIndex - 1];

		}

	}

}