public boolean isUnique() {
        if (head != null && head.getNext() != null) {
            Node pointer = head;
            Node comparator;
            while (pointer != null && pointer.getNext() != null) {
                comparator = pointer.getNext();
                while (comparator != null) {
                    if (pointer.getValue() == comparator.getValue()) {
                        return false;
                    }
                    comparator = comparator.getNext();
                }
                pointer = pointer.getNext();
            }
        }
        return true;
    }