Creating Java tabbed web browser - help urgently needed
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    Join Date
    Apr 2009
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    Creating Java tabbed web browser - help urgently needed

    Hi

    i am doing a 2nd year Java course, and have to create a tabbed web browser in Java.however i cant use inbuilt classes,like JTabbedPane,DefaultMutableTreeNode etc. i have to make everything myself, i am trying not to freak out.

    The first part was to create a circular list which will be used to implement the tabs. This is the given circular list ADT which i had to implement:

    Code:
    package cs214.lists;
    
    import cs214.common.Position;
    
    /**
     * Interface for a circular linked list. The list has a single access point,
     * called the cursor, which may be adjusted to access the data in the list.
     * 
     * @param <E>
     *            the type of data to store at each list position.
     */
    public interface CircularListADT<E> extends Iterable<E> {
    
    	/**
    	 * Returns the number of elements (alternatively, positions) in the list.
    	 * 
    	 * @return the number of elements in the list.
    	 */
    	public int size();
    
    	/**
    	 * Tests whether the list is empty.
    	 * 
    	 * @return <code>true</code> if the list is empty, and <code>false</code> if
    	 *         it is not.
    	 */
    	public boolean isEmpty();
    
    	/**
    	 * Returns the cursor position in the list.
    	 * 
    	 * @return the cursor position.
    	 * @throws EmptyListException
    	 *             if the list is empty.
    	 */
    	public Position<E> cursor() throws EmptyListException;
    
    	/**
    	 * Removes the cursor position from the list, and returns its element. The
    	 * cursor is advanced to the next position in the list, if there is one.
    	 * 
    	 * @return the element stored in the removed position.
    	 * @throws EmptyListException
    	 *             if the list is empty.
    	 */
    	public E remove() throws EmptyListException;
    
    	/**
    	 * Adds a new position containing the specified element to the list. If the
    	 * list is non-empty, the position is added directly after the current
    	 * cursor; if the list is empty, it becomes the only, first element and
    	 * cursor.
    	 * 
    	 * @param element
    	 *            the element to store at the new position.
    	 */
    	public void add(E element);
    
    	/**
    	 * Moves the cursor to the next position in the list.
    	 * 
    	 * @throws EmptyListException
    	 *             if the list is empty.
    	 */
    	public void advance() throws EmptyListException;
    
    	/**
    	 * Moves the cursor to the previous position in the list.
    	 * 
    	 * @throws EmptyListException
    	 *             if the list is empty.
    	 */
    	public void retreat() throws EmptyListException;
    
    }
    I implemented this in a Circular List file:

    Code:
    package cs214.lists;
    
    import cs214.common.Position;
    import cs214.lists.CNode;
    
    import java.util.Iterator;
    import java.lang.UnsupportedOperationException;
    
    //import cs214.lists.CNode.Node;
    
    public class CircularList<E> implements CircularListADT<E> {
    
    	protected int size;
    	protected CNode<E> cursor = null;
    	protected CLIterator <E>it;
    
    	public CircularList(){
    		size = 0;
    	}
    	public boolean isEmpty() {
    		
    		return cursor == null;
    	}
    
    	
    	public int size() {
    		return this.size;
    
    	}
    
    	public Position<E> cursor() throws EmptyListException {
    		
    		if (cursor == null) {
    			throw new EmptyListException("The list is empty.");
    		}
    		return cursor;
    
    	}
    
    	public E remove() throws EmptyListException {
    		
    		CNode<E> n = cursor.getPrevious();
    		CNode<E>m = cursor.getNext(); 
    		
    		if (cursor == null) {
    			throw new EmptyListException("The list is empty.");
    		}
    
    		else {
    			n.setPrevious(m);
    			m.setNext(n);
    			
    			cursor.setPrevious(null);
    			cursor.setNext(null);
    			
    			size--;
    			/*n = cursor;
    			n.next = cursor.next;
    			cursor = n.next;*/
    		}	
    		
    		return cursor.value;
    	}
    	
    	public void add(E element) {
    
    		CNode<E> n = new CNode<E>(element,cursor,cursor.getPrevious());
    
    		if (cursor == null) {
    			n.next = n;
    			cursor = n;
    		}
    
    		else {
    			n.next = cursor.next;
    			cursor.next = n;
    			cursor = n;
    
    		}
    	}
    
    	public void advance() throws EmptyListException {
    		
    		if (cursor == null) {
    			throw new EmptyListException("The list is empty.");
    		}
    
    		else {
    			it = new CLIterator<E>(cursor);
    			cursor = cursor.next;
    		}
    
    	}
    	
    	public void retreat() throws EmptyListException{
    		
    		if (cursor == null) {
    			throw new EmptyListException("The list is empty.");
    		}
    	}
    	
    /*	public Iterator<E> getIterator()	{
    		return it;
    	}
    */
    	public Iterator<E> iterator(){
    		
    		return new CLIterator<E>(cursor);
    	}
    
    	 class CLIterator<E> implements Iterator<E> {
    		 CNode<E> cursor;
    		 
    		public CLIterator(CNode<E> cursor)	{
    			this.cursor = cursor;
    		}
    
    		@Override
    		public boolean hasNext() {
    			
    			return false;
    		}
    
    		@Override
    		public E next() {
    			cursor = cursor.getNext();
    			return cursor.element();
    		}
    
    	
    		public void remove() throws UnsupportedOperationException{
    			if (cursor ==null){
    				throw new UnsupportedOperationException();
    			}
    			
    			
    		}
    	}
    }
    This is the Position interface:

    Code:
    package cs214.common;
    
    /**
     * A position in a relatively-defined data structure. Allows a user access to an
     * element stored at the position, without breaking encapsulation and exposing
     * implementation dependent links to other positions.
     * 
     * @param <E>
     *            the type of element stored at the position.
     */
    public interface Position<E> {
    
    	/**
    	 * Returns the element associated with this position.
    	 * 
    	 * @return the element associated with this position.
    	 */
    	public E element();
    
    }
    and the CNode class which i created to define nodes in the circular list:
    Code:
    package cs214.lists;
    
    import cs214.common.Position;
    
    public class CNode<E> implements Position<E> {
    
    	protected E value;
    	protected CNode<E> next,prev;
    
    
    	public CNode(E element, CNode<E> n, CNode<E> p){
    		value = element;
    		next = n;
    		prev = p;
    	}
    
    	//public CNode(E element2) {
    	// TODO Auto-generated constructor stub
    	//}
    
    	public E element() {
    		return value;
    	}
    
    	public CNode<E> getPrevious(){
    		return prev;
    	}
    
    	public CNode<E> getNext(){
    		return next;
    	}
    
    	public void setElement(E newElement){
    		value = newElement;
    	}
    
    	public void setPrevious(CNode<E> newPrevious){
    		prev = newPrevious;
    	}
    
    	public void setNext(CNode<E> newNext){
    		next = newNext;
    	}
    	
    	public String toString(){
    		return"This is a node and this is what is inside it " + value;
    	}
    }

    My problem is, i dont know how to test if this actually works. Im supposed to make a simple GUI which will create a new tab, close it etc. attached is the actual question. I would appreciate any help at all, because i cant move on to the next part if i dont fix this asap.
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