public int compareDate(Task task1, Task task2) {
		if (task1.getDeadline() == null && task2.getDeadline() == null) {
			return 0;
		} else if (task1.getDeadline() != null && task2.getDeadline() == null) {
			return 1;
		} else if (task1.getDeadline() == null && task2.getDeadline() != null) {
			return -1;
		} else if (task1.getDeadline() != null && task2.getDeadline() != null) {
			return task1.getDeadline().compareTo(task2.getDeadline());
		}

		return 0;
	}