Overview

The main goal of this lab is to get some practice writing code involving a singly linked list. We have written a driver which creates a singly-linked list of a given size, where the individual element values are chosen at random. The implementation for the list is as described in Ch. 4.3 of the text. In particular the head is a reference to the node of the list containing the first element. The node of the list which contains the final element will have a Next reference equal to null. (This is a different convention from the text's treatment of doubly-linked lists in Ch. 4.4.)

Your job is to write code for the following two routines in the file Student.java. We strongly recommend that you achieve success on the first task before you attempt the second.

• public int size(Node head)
  Given a reference to the head of the list, you are to walk the list and count the number of Object's on the list.

• public Node search(Node head, Object obj)
  You are to walk the list looking for a node which contains an element "equivalent" to obj. Before you write this routine, please see the section of the general programming webpage which discusses equivalence of objects in Java.

Driver

The driver for this program is a Java Applet, which we have written to give you a graphical interface. The first thing you should do is to download all of the files we provide and compile and run them as given. If you are not yet familiar with how to run an Applet in your particular Java development platform, further details are given in the general programming webpage.

When you run the applet, you should see a singly-linked list of length 5 drawn on the screen. The challenge now is for you to implement the code for the size() and search() methods.

Files you will need

Although you will only need to modify one file (Student.java), you will need to download several files we provide.

Testing

Be sure to test your program on a variety of situations. For instance, you should test your size() routine to make sure that it works properly on an empty list, or a list with only one or two items. You should test your search() routine on special cases such as searching for the very first item, the very last item, or for an item which is not on the list.

Handing in your completed lab

When you have tested your methods and you are satisfied that they work, please print out the modified file Student.java and give this copy to the TA. Please make sure that your name appears at the top of the page. You do not have to submit anything electronically for this lab.