public void set(int index, Object o) {
		if(index + 1 > array.length) {
			resizeArray(index + 1);
		}
		if( array[index] != null && o == null) {
			numElements -= 1;
		} if( array[index] == null && o != null) {
			numElements += 1;
		}
		array[index] = o;		
	}