Urgent help needed - writing/ reading to/from file

Question

hi all..
can anyone help me with this problem:
The problem dioscussed in www.javaworld.com forum
any clues what the problem is??

Answer 1

hi all...
i managed to get the gui set up, and the JList is finally loading the data,
yet, i am having problems with displaying relevant data of each item in the list...
could you please help??
// required imports
   import javax.swing.*;
   import java.awt.*;
   import java.awt.event.*;
   import javax.swing.event.*;
   import java.io.*;
   import java.util.*;
// ViewPanel class: the panel for the view pane. handles its own events.
   public class ViewPanel extends JPanel implements ListSelectionListener
      private JList list;
      private DefaultListModel listModel;
      private JButton deleteButton;
      private TicketStorage data;
   // add pane items
      private JLabel seat, seatData;
      private JLabel name, nameData;
      private JLabel duration, durationData;
      private JLabel price, priceData;
      private JCheckBox waiterService;
   // creating panels
      JPanel p1 = new JPanel();
      JPanel p2 = new JPanel();
      public ViewPanel(TicketStorage data)
      // store data structure reference
         this.data = data;
         TrainTicket[] summary = data.summary();         
         listModel = new DefaultListModel();
         for (int i = 0; i < summary.length; i++)
            listModel.addElement(summary.getSeat());
list = new JList(listModel);
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.setSelectedIndex(0);
list.setVisibleRowCount(5);
JScrollPane listScroller = new JScrollPane(list);
listScroller.setPreferredSize(new Dimension(100, 150));
seat = new JLabel("Seat No:");
seatData = new JLabel();
name = new JLabel("Name:");
nameData = new JLabel();
duration = new JLabel("Duration:");
durationData = new JLabel();
price = new JLabel("Price:");
priceData = new JLabel();
// create add pane items
waiterService = new JCheckBox("Waiter Srevice");
waiterService.setEnabled(false);
// waiterService.addActionListener(boxListener);
JButton deleteButton = new JButton("Delete");
// deleteButton.addActionListener(buttonListener);
// adding listeners to the components
//deleteButton.addActionListener(this);
//waiterService.addActionListener(this);
list.addListSelectionListener(this);
// adding the components to their coreesponding panels
p1.setLayout(new GridLayout(5,1));
p1.add(seat);
p1.add(name);
p1.add(duration);     
p1.add(price);
p1.add(waiterService);
p2.setLayout(new GridLayout(5,1));
p2.add(seatData);
p2.add(nameData);
p2.add(durationData);     
p2.add(priceData);
p2.add(deleteButton);
this.setLayout(new GridLayout(1,3,3,0));
this.add(listScroller);
this.add(p1);     
this.add(p2);
public void valueChanged(ListSelectionEvent e)
if (e.getValueIsAdjusting() == true)
// enable the delete button when an item is selected
deleteButton.setEnabled(true);
// retrieve the sellected seat number value
String itemSellected = listModel.getElementAt(list.getSelectedIndex()).toString();
// retrieve the ticket with the sellected seat number
TrainTicket tk = data.retrieve(itemSellected);
// load the relevant data of a sellected ticket
seatData.setText(tk.getSeat());
nameData.setText(tk.getName());
durationData.setText(Integer.toString(tk.getDuration()));
priceData.setText(Double.toString(tk.getPrice()));
/*/ if the selected ticket of type first class
if(tk instanceof FirstClassTicket)
if(((FirstClassTicket)tk).getWaiter()==true)
waiterService.setSelected(true);
waiterService.setEnabled(true);
else
waiterService.setSelected(false);
waiterService.setEnabled(true);
else
waiterService.setSelected(false);
waiterService.setEnabled(false);
the application runs, it loads the data available in the linked list,
yet, on switching from an item to another in the list, it keeps generating errors!!!
in addition to the fact that it does not display the data!!
for more info refer to the url in my first post!
any clues??