Add an object to a linked list and a database

I have an assignment due next week and could really do with the help. At the moment i am trying to add an object (book) to a linked list and to the database.
I am not able to work out how to add the object to the database.

Main program - Code asking he user to input the book details. It connects to the database.

Code java:

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        else if (choice == 2)
        {         
 
            String userid=" ";
            String password=" ";
            String host=" ";
            String database=" ";
 
            String url = "jdbc:mysql://...";
 
            Connection conn = DriverManager.getConnection(url, userid, password);
            Statement stmt = conn.createStatement( );
            String query = "SELECT * FROM books";
            ResultSet rs = stmt.executeQuery(query);  
 
            System.out.print("Enter Book ID: ");
            id = in.next();
 
            System.out.print("Enter Book Title: ");
            title = in.next();
 
            System.out.print("Enter Author's First Name: ");
            firstName = in.next();
 
            System.out.print("Enter Author's Last Name: ");
            lastName = in.next();
 
            System.out.print("Enter Price: ");
            price = Double.parseDouble(in.next());
 
            System.out.print("Enter Year: ");
            year = Integer.parseInt(in.next());    
 
            Book b2 = new Book(id, title, firstName, lastName, price, year);
 
            list.add(b2);
 
            System.out.println("");
            System.out.println("Added following book");
            System.out.println("Title: " + b2.getTitle());
            System.out.println("Author's First Name: " + b2.getFirstName());
            System.out.println("Author's Last Name: " + b2.getLastName());
            System.out.println("Price: " + b2.getPrice());
            System.out.println("Year: " + b2.getYear());
        }

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DoubleLinkedList program - Code that adds book to linked list.

Code java:

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    public void add(Book b) 
    {
        Node newNode=new Node();
        newNode.data=b;
        if(current==null)
        {
            newNode.next=first;
            newNode.prev=null;
 
            if(first!=null)
            {
            first.prev=newNode;
            }
            else
            {      
                last=newNode;
            }   
            first=newNode;
            current=newNode;
        }
 
        else if(current!=null)
        {
 
            newNode.prev=current;
            newNode.next=current.next;
 
            if(current==last)
            {
                last=newNode;
            }
            else
            {
                current.next.prev=newNode;
            }
            current.next=newNode;           
        }
        numElements++;
    }

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