Question

I am trying to have a window open and have it display the text from a file. However when I run it, I simply get a blank window. Here is the code for the window – I get no errors from eclipse at all.

package presentation;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

import domain.Items;
import services.exceptions.ItemNotFoundException;
import services.itemservice.*;

public class ShowAllInventory extends JFrame {

    /**
     * 
     */
    private static final long serialVersionUID = -4498395613773129897L;
    private JPanel contentPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    ShowAllInventory frame = new ShowAllInventory();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the window frame.
     */
    public ShowAllInventory() throws ItemNotFoundException {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        /**
         * Load the inventory
         */

        IItemsService service = new ItemsServiceImpl();
        try {
            Items items = service.getItems();
        } catch (ItemNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println ("Items Not Found");
        }

    }

}

Here is the code for the interface the code is calling –

    public Items getItems () throws ItemNotFoundException;

}

And here is the implementation…

/**
 * Getting Items from the database
 * @return 
 * @throws ItemNotFoundException
 */
@Override
public Items getItems() throws ItemNotFoundException {

    Items items = (Items) null;
    try {
        ObjectInputStream input = new
                ObjectInputStream (new FileInputStream("itemdatabase"));
        items = (Items)input.readObject();
        input.close();
    } catch (IOException ioe) {
        System.out.println ("IOException");
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }       
    return items;       
}

Answer 1

I don’t know if your IItemsService can load the file properly. But most likely you get a blank window because in your code, I think you forgot to add a component to display the items. If your Items works as a List. You can use a JList to display them.

Item[] items = ...// use your Items to populate Item to an array
JList itemList = new JList(items);

JScrollPane scrollPane = new JScrollPane(itemList);
scrollPane.setPreferredSize(new Dimension(300, 100)); //put your preferred size here

contentPane.add(scrollPane);

IMHO, I think you should not throw ItemNotFoundException since finding no items should be a normal case. FileNotFoundException should be the one to be thrown here.

---

UPDATED
If you want to use JTextField or JTextArea you have to something like this:

...
Items items = service.getItems();
...

String itemContent = items.toString(); // you have to put meaningful information from class Items to this String
JTextArea itemDisplay = new JTextArea(itemContent);
// JTextField itemDisplay = new JTextField(itemContent);

JScrollPane scrollPane = new JScrollPane(textArea);
scrollPane.setPreferredSize(new Dimension(300, 100)); //put your preferred size here

contentPane.add(scrollPane);