Implementing my own linked lists...aiiieee!

Question

Hi,
I'm trying to implement my own linked list structure oftype String. It will eventually go to form a simple text editor, with each line of a file being loaded into its own String node.
However, im having problems implementing the list itself :)
So far ive got the file to read in succesfully, but now im stuck...how do i load up a line into a new node? and what about the head/tail nodes, they just confuse me! Do i have to write a seperate 'List' class and create an object of that, much like the LinkedList class with Java?
Any help or a nudge in the right direction would be appreciated,
TIA
andrew
PS code below ...
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import java.io.*;
import java.util.*;
class Editor {
public static void main(String[] args) {
///LOAD UP THE TEXT FILE//////////////////////////////////////
     String file = "s.txt";
     String line;
     System.out.println(System.in);
     //testing here...
StringNode alist = new StringNode(null,null);
     try{
          FileReader FR = new FileReader(file);
          BufferedReader BR = new BufferedReader(FR);
          while ( (line = BR.readLine()) != null ){
               alist.addNodeAfter(line);
               System.out.println(line);
               }//while
     }//try
     catch(IOException e){
          System.out.println(file + " not found");
     }//catch
///COMMANDS///////////////////////////////////////////////////
//text editor commands to be input via command line type console. how to grab inputs on return?
}//main
}//Editor
//code to create a node...but now what?
     class StringNode
     private String data;
     private StringNode link;
     // constructor for initialisation
     public StringNode(String initialData, StringNode initialLink)
          data = initialData;
          link = initialLink;
     // accessor method to get the data from this node
     public String getData( )
          return data;
     // accessor method to get a reference to the next node after this node.
     public StringNode getLink( )
          return link;
     // modification method to set the data in this node.
     public void setData(String newData)
          data = newData;
     // modification method to set the link to the next node after this node
     public void setLink(StringNode newLink)
          link = newLink;
     // add a new node after this node
     public void addNodeAfter(String item)
          link = new StringNode(item, link);
     // modification method to remove the node after this node.
     public void removeNodeAfter( )
          link = link.link;
     // compute the number of nodes in a linked list
     public static int listLength(StringNode head)
          StringNode cursor;
          int answer;
          answer = 0;
          for (cursor = head; cursor != null; cursor = cursor.link)
               answer++;
          return answer;
     // print the nodes in a linked list
     public static void listPrint(StringNode head)
          StringNode cursor;
          for (cursor = head; cursor != null; cursor = cursor.link)
               System.out.println(cursor.getData());
     // print the nodes in a linked list skipping dummy node at head
     public static void listPrint2(StringNode head)
          StringNode cursor;
          for (cursor = head.link; cursor != null; cursor = cursor.link)
               System.out.println(cursor.getData()+" ");
     // search for a particular piece of data in a linked list
     public static StringNode listSearch(StringNode head, String target)
          StringNode cursor;
          for (cursor = head; cursor != null; cursor = cursor.link)
               if (target == cursor.data)
                    return cursor;
          return null;
}

Answer 1

You wouldn't by any chance be doing computer science at Cardiff university would you and have been given this as an assignment?