// File: TestList4.java
//
// Author: Rahul Simha
// Created: Sept 1998
//
// A linked list in Java - v4. For any kind of object.


// A node that contains any "Object"

class ListItem {

    Object data = null;    // The universal Object.
    ListItem next = null;
    
    // Constructor.
    public ListItem (Object obj)
    {
	data = obj;  next = null;
    }
    
    // Accessor.
    public Object getData () 
    {
	return data;
    }
}


// Linked list class - also a dynamic class.

class LinkedList {

    ListItem front = null;
    ListItem rear = null;
    int numItems = 0;      // Current number of items.
    
    // Could this class use a constructor?

    // Instance method to add a data item.
    public void addData (Object obj)
    {
	if (front == null) {
	    front = new ListItem (obj);
	    rear = front;
	}
	else {
	    rear.next = new ListItem (obj);
	    rear = rear.next;
	}
	numItems++;
    }

    public void printList ()
    {
	ListItem listPtr = front;
	System.out.println ("List: (" + numItems + " items)");
	int i = 1;
	while (listPtr != null) {
	    System.out.println ("Item# " + i + ": " 
				+ listPtr.getData());
                                // Must implement toString()
	    i++;
	    listPtr = listPtr.next;
	}
    }

} // End of class "LinkedList"


// An object to use in the list:

class Person {

    String name;
    String ssn;
    
    // Constructor.
    public Person (String nameInit, String ssnInit)
    {
	name = nameInit;  ssn = ssnInit;
    }

    // Override toString()
    public String toString ()
    {
	return "Person: name=" + name + ", ssn=" + ssn;
    }
    
} // End of class "Person"


// Test class.

class TestList4 {

    public static void main (String[] argv)
    {
	// Create a new list object.
	LinkedList L = new LinkedList ();
	
	// Create a Person instance and add it to list.
	Person p = new Person ("Terminator", "444-43-4343");
	L.addData (p); // p is a subclass of Object and so
	// p is automatically cast to Object
	
	// We don't really need a Person variable:
	L.addData (new Person ("Rambo", "555-54-5454"));
	L.addData (new Person ("James Bond", "666-65-6565"));
	L.addData (new Person ("Bruce Lee", "777-76-7676"));
	
	// Print contents.
	L.printList();
    }

} // End of class "TestList4"