Test class

Hi,
How do I write a Test class for class LinkedList?

<font size=2.5>
public class LinkedList
{
    
    private List head;
        public LinkedList()
    {
        // initialise instance variables
        head = null;
    }

public List readIntValues ()
    {
        int i = io.readInt("Please type in an integer! ");
        List nl = null; 
        while (i != 0)
        {
            nl = new List(); // create a new List element
            nl.setElem(i);
            nl.setNext(head);
            head = nl;
            i = io.readInt("Please type in next integer! ");
        }
        return (head);
    }
    
    public void printList (List h)
    {
        if (h == null)
        {
            System.out.println("End of list reached");
        }
        else 
        {
            System.out.println(h.getElem());
            printList(h.getNext());
        }
    }
    public List deleteElem (List h, int i)
    {
        if (h != null) 
        {
            if (h.getElem() == i) 
                return h.getNext(); 
            else 
                {
                    h.setNext(deleteElem(h.getNext(), i)); 
                    return h;
                }
        }
        return null;
    }
   
    public List addElem (List h, int i)
    {
        if (h == null)
            return new List (i,h); 
        else if (h.getElem() > i) 
                return new List (i,h); 
        else 
            {
                h.setNext(addElem(h.getNext(), i)); 
                return h;
            }
    }
    
    public boolean inList (List h, int i)
    {
        if (h == null)
            return false; 
        else if (h.getElem() == i) 
                return true; 
        else 
            return inList(h.getNext(), i);
    }
    }

[This message has been edited by Cindy Glass (edited September 24, 2001).]

Hi Jim -
There's a couple things missing from the code; in the readIntValues() method, there's a reference to io that isn't supported anywhere else in the class. One can assume it's an InputStream or Reader, but since it isn't declared or instantiated anywhere, I can only assume "io" is supposed to be a stand-in for System.in.
On the other hand, I don't know which class (if any) allows you to prompt the user as a argument to some input type, and expect an integer in return. It's been a while since I've done any client-side java and I don't have the JDK docs at hand, so I dunno know. But we need a little more to go on here.
------------------
Michael Ernest, co-author of: The Complete Java 2 Certification Study Guide

Hi Mr. Ernest,
Thank you for answering my question.
I forgot to send the rest of the code. Here they are.
public class List
{

private int element;
private List next;
public List()
{

element = 0;
next = null;
}
public List(int elem, List nextElem)
{
element = elem;
next = nextElem;
}
public void setElem(int someElement)
{
element = someElement;
}
public void setNext(List newNext)
{
next = newNext;
}
public int getElem()
{
return element;
}
public List getNext()
{
return next;
}
}
public class io
{
public io()
{
}

static String readString()
{ int ch;
String r = "";
boolean done = false;
while (!done)
{ try
{ ch = System.in.read();
if (ch < 0 | | (char)ch == '\n')
done = true;
else if ((char)ch != '\r')
r = r + (char) ch;
}
catch(java.io.IOException e)
{ done = true;
}
}
return r;
}

static void printPrompt(String prompt)
{ System.out.print(prompt + " ");
System.out.flush();
}

static int readInt(String prompt)
{ while(true)
{ printPrompt(prompt);
try
{ return Integer.valueOf
(readString().trim()).intValue();
} catch(NumberFormatException e)
{ System.out.println
("Not an integer. Please try again!");
}
}
}

static void error(String err)
{
throw new Error(err);
}

}

Have you considered using the LinkedList class java.util.LinkedList? I would test your program against it. After all it is a concrete collection. It is easy to use.
------------------

But I still don't know how to write a test class.
How do I start?

You can just add a main() method to your LinkedList class and work with it.
Or you can create a separate class Test that has the main and use it to test your stuff.

[This message has been edited by Cindy Glass (edited September 25, 2001).]