Putting a class of objects in a Linked List?

Question

Hi,
I copied a program from a book and I want to edit it and put studentRecord class in the Linked List. I've tried to play about with datum, but everything I try doesn't work. Can someone help me out? How could I put studentRecord in the LinkedList?
import java.io.*;
class IO
     static BufferedReader keyboard = new
          BufferedReader(new InputStreamReader(System.in));
     static PrintWriter screen = new PrintWriter(System.out, true);
class studentRecord
     private String name;
     private int IDNumber;
class LinkedList
     class Node
          protected Object datum;
          protected Node link;
          public Node() {}
          public Node(Object item, Node pointer)
               datum = item;
               link = pointer;
     private Node head;
     private Node tail;
     private Node temporary;
     private int nodeCount = 0;
     //constructor
     public LinkedList()
          head = null;
          tail = null;
          temporary = null;
     //method to insert an object into the linked list
     public void insert(Object datum)
          if (head == null) // list empty
               head = new Node(datum, head);
               tail = head;
          else
               temporary = new Node(datum, temporary);
               tail.link = temporary;
               tail = temporary;
               temporary = null;
          nodeCount++;
Full program can be found: http://dil3mma.tripod.com/LinkedList.txt
Thanks in advance.

Answer 1

Hi jverd,
Thanks for replying. I've tried to change the program liked you said but there is 1 error I can't seem to fix(Im sure there are more tho). The error is "cannot resolve symbol" I typed in caps the line it happens on so it's easy to see. Any idea what it could be? Is it cause I'm comparing a String with Object?
import java.io.*;
class IO
     static BufferedReader keyboard = new
          BufferedReader(new InputStreamReader(System.in));
     static PrintWriter screen = new PrintWriter(System.out, true);
class sRecord
     private String name;
     private int IDNumber;
class LinkedList
     class Node
          protected sRecord datum;
          protected Node link;
          public Node() {}
          public Node(sRecord item, Node pointer)
               datum = item;
               link = pointer;
     private Node head;
     private Node tail;
     private Node temporary;
     private int nodeCount = 0;
     //constructor
     public LinkedList()
          head = null;
          tail = null;
          temporary = null;
     //method to insert an object into the linked list
     public void insert(sRecord datum)
          if (head == null) // list empty
               head = new Node(datum, head);
               tail = head;
          else
               temporary = new Node(datum, temporary);
               tail.link = temporary;
               tail = temporary;
               temporary = null;
          nodeCount++;
     //method to delete an object from the linked list
     public boolean delete(Object scrap)
          Node previous = head;
          //for every node in the linked list
          for (Node current = head; current != null; current = current.link)
               //node to be deleted is at the head of the list
               if (current.datum.equals(scrap) && previous == current)
                    head = current.link;
                    if (head == null) tail = null;
                    nodeCount--;
                    return true;
               //node to be deleted is after the first node and before the last
               else if (current.datum.equals(scrap) && (current.link != null))
                    previous.link = current.link;
                    nodeCount--;
                    return true;
               //node to be deleted is at the ned of list
               else if (current.datum.equals(scrap) && (current.link == null))
                    tail = previous;
                    previous.link = null;
                    nodeCount--;
                    return true;
               previous = current;
          return false;
     //method to display the contents of a linked list
     public void displayList()
          Node temporary = head;
          if (head == null)
               IO.screen.println("linked list is empty");
               return;
          while (temporary != null)
               IO.screen.println(temporary.datum);
               temporary = temporary.link;
     //method to return true if the linked list is empty
     public boolean isEmpty()
          return (nodeCount == 0);
     //method to return the number of nodes in the linked list
     public int nodes()
          return nodeCount;
     //method to display a menu to insert data into the linked list
     static private char menu()
          char response = '\u0000';
          IO.screen.println("Do you want to ");
          IO.screen.print("nsert, [D]elete, [L]ist, [E]xit? ");
          IO.screen.flush();
          boolean done=false;
          do
               try
                    String data = IO.keyboard.readLine();
                    response = Character.toUpperCase(data.charAt(0));
                    done = true;
               catch (Exception e)
                    IO.screen.println("Please input a single character I, D, L or E");
          } while (! done);
          return response;
     static public void main(String[] args) throws IOException
          LinkedList list = new LinkedList();
          String datum;
          char choice;
          //get information from menu
          choice = menu();
          for (;;)
               //Menu
               switch (choice)
                    case 'I' :
                         IO.screen.println("type quit to finish input");
                         IO.screen.print("Enter a word ");
                         IO.screen.flush();
                         datum = IO.keyboard.readLine();
                         while (! datum.equals("quit"))
THE ERROR HAPPENS HERE ON THIS LINE          list.insert(datum.name);
                              IO.screen.print("Enter another word");
                              IO.screen.flush();
                              datum = IO.keyboard.readLine();
                         break;
               case 'D' :
                    //if list is empty deletion not possible
                    if (list.isEmpty())
                         IO.screen.println("linked list is empty");
                         break;
                    IO.screen.println("type quit to finish input");
                    IO.screen.print("Delete? ");
                    IO.screen.flush();
                    datum = IO.keyboard.readLine();
                    while (! datum.equals("quit"))
                         if (list.delete(datum))
                              IO.screen.println(datum+" was scrapped!");
                         //if list is empty deletion is not possible
                         if (list.isEmpty())
                              IO.screen.println("linked list is empty");
                              break;
                         IO.screen.print("Delete? ");
                         IO.screen.flush();
                         datum = IO.keyboard.readLine();
                    break;
               case 'L' :
                    list.displayList();
                    IO.screen.println("number of nodes " + list.nodes());
                    break;
               case 'E' : System.exit(0);
          //get information from menu
          choice = menu();