public void doAdd()
    {
        String item = JOptionPane.showInputDialog(this, "Please enter item to add to queue.", "");
        boolean itemAdded = false;

        if(item == null || item.equals(""))
        {
            textArea.setText("Unable to add item to queue: Item must not be an empty String.");
            return;
        }
        
        if(!(queueList.isFull()))
        {
            itemAdded = queueList.add(item);

            if(itemAdded)
            {
                textArea.setText("The following item was successfully added to the " +
                    "queue: " + item + "\n\n" + 
                    "Current queue contents:\n" + queueList);
                
                updateSetSizeField();
                updateSetSpaceField();
            }
            
            else
            {
                textArea.setText("Unable to add the following item to queue: " + item + 
                    "\n\n" +
                    "Current queue contents:\n" + queueList);
            }
        }
        
        else  //if(queueList.isFull())
        {
            textArea.setText("Unable to add item to queue: Queue is full.");
        }
        
        return;
            
    }//end doAdd()