Iliev's homework-23_1-Methods

public class iliev {
    private Object[] arr;
    private int count;
    private static final int INITIAL_CAPACITY = 10;

    public iliev() {
        arr = new Object[INITIAL_CAPACITY];
        count = 0;
    }

    public int getLength() {
        return count;
    }

    public void add(Object item) {
        add(count, item);
    }

    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;
    }

    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;
    }

    public void clear() {
        arr = new Object[0];
        count = 0;
    }

    public boolean contains(Object item) {
        int index = indexOf(item);
        boolean found = (index != -1);
        return found;
    }

    public Object elementAt(int index) {
        if (index >= count || index < 0) {
            throw new IndexOutOfBoundsException("Invalid index: " + index);
        }
        return arr[index];
    }

    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;
    }

    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;
    }
}