CODEWITHSUNDEEP
javaswingnetbeansjlist
MichalB
MichalB

Reputation: 3341

The elements not added to JList

I am trying to add file names to my JList but without success. Here is the piece of the code: 

DefaultListModel model = new DefaultListModel();
listLayer.setModel(model);
model.addElement(file.getName());

listLayer is a JList into which I would like to add file name. For information, I am writing my GUI application in netBeans so I can not create a new JList object within this code as it was already created automatically when added JList to my layout. Therefore I can just access it through its methods.

Thanks a lot, Michal.

-------------------------------------------------------------------------

Ok I will try to extend it more:

private void openActionPerformed(java.awt.event.ActionEvent evt) {                                     

    JFileChooser fileChooser = new JFileChooser("C:/");

    FileFilter filter1 = new MyCustomFilter();
    fileChooser.setFileFilter(filter1);

    int returnVal = fileChooser.showOpenDialog(this);

    if (returnVal == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();

            //String[] tokens = file.getName().split(".");
            //String name = tokens[0];

            DefaultListModel model = new DefaultListModel();
            listLayer.setModel(model);
            model.addElement(file.getName());

    } else {
        System.out.println("File access cancelled by user.");
        }
}

and yes, my JList called listLayer is declared in non-modifiable section of the code like this: private javax.swing.JList listLayer;

Thanks again for any help. Michal

Upvotes: 3

Views: 698

Answers (2)

trashgod
trashgod

Reputation: 205785

You recommend me to use not DefaultListModel, but ListModel?

I don't know enough about the rest of your program to say. If you have a single, relatively static JList, DefaultListModel may be perfect. If your program models a constantly changing selection of File instances, then you may want to implement ListModel or even a shared model, as shown here. The latter simply forwards some methods to the default implementation.

Upvotes: 1

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285405

Thanks for posting more code. Now quite possibly we can answer your question. A problem I see is that you're recreating a DefaultListModel each time the button is pressed and setting the JList with this new model effectively removing all data that was previously held by the list. A way to avoid doing this is to simply get the model that the JList already has, which should be a DefaultListModel, and add items to it. You will need to cast the object returned by getModel() since per the API, Java only knows this to be a ListModel object, and ListModel doesn't have the addElement(...) method that DefaultListModel does.

Something perhaps like so: 

if (returnVal == JFileChooser.APPROVE_OPTION) {
        File file = fileChooser.getSelectedFile();

        // note the cast since getModel() only returns a ListModel
        DefaultListModel model = (DefaultListModel)listLayer.getModel(); // changed**

        model.addElement(file.getName());

}

Upvotes: 2

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