public void sortList() {
        Node current = null, index = null;
        int temp;
        //Check whether list is empty
        if(head == null) {
            return;
        }
        else {
            //Current will point to head
            for(current = head; current.next != null; current = current.next) {
                //Index will point to node next to current
                for(index = current.next; index != null; index = index.next) {
                    //If current's data is greater than index's data, swap the data of current and index
                    if(current.data > index.data) {
                        temp = current.data;
                        current.data = index.data;
                        index.data = temp;
                    }
                }
            }
        }
    }