List field in blackberry , event click listener not working

Question

I am working on BB OS v5.0. I have managed to get the list to appear on the screen. I am getting data from webservice and adding it into a Vector.

Now I want to find out onclick, which is the item that is clicked and accordingly perform some operation. For that i am trying to display an alert. But I'm not getting the alert.

Here is my code :

In my mainscreen , i added fieldmanager=new VerticalFieldManager(); and add(fieldmanager);

void fetchAlbumsForLetter(String letter) {
    Status.show("Processing ....", 3000);
    fieldManager.deleteAll();

    VerticalFieldManager top = new VerticalFieldManager(Manager.NO_HORIZONTAL_SCROLL | Manager.NO_HORIZONTAL_SCROLLBAR | Manager.VERTICAL_SCROLL | Manager.VERTICAL_SCROLLBAR | Field.USE_ALL_WIDTH){
        public void paint(Graphics graphics) {
            graphics.setBackgroundColor(0x00290008);
            graphics.setColor(Color.WHITE);
            graphics.clear();
            graphics.drawBitmap(0, 0, sha.getWidth(),
            sha.getHeight(), sha, 0, 0);
            super.paint(graphics);
        }
    };
    add(top);

    CustomListField4 list4 = new CustomListField4(null){
        protected boolean navigationClick(int status, int time) {
            getValue4();
            return true;
        }
    };
    fieldmanager.add(list4);
}

protected void getValue4() {
    Field f = getFieldWithFocus();
    if (f instanceof ListField) {
        ListField l = (ListField) f;
        final int index = l.getSelectedIndex();
        HistoryItem _contactslist = (HistoryItem) CustomListField4.val4.elementAt(index);
        final String id = _contactslist.getName();
        Dialog.alert(id+"");
    }
}

Please help me to resolve this

EDIT

class CustomListField4 extends ListField implements ListFieldCallback {

    public CustomListField4(Vector data) {
        super(0, ListField.MULTI_SELECT);
        final TableRowManager row = new TableRowManager() {
            public void paint(Graphics g) {
                // g.fillRect(0, 0, getWidth(), getHeight());
                g.setColor(0x0f3e19b);
                g.clear();
                super.paint(g);
            }
        };

        Bitmap icon = Bitmap.getBitmapResource("Devil Skype.png");
        HorizontalFieldManager h=new HorizontalFieldManager();
        h.add(new BitmapField(icon));
        //h.add(new BitmapField(song.getThumb()));
        h.add(new LabelField(song.getAlbumName()));
        //h.add(new LabelField(row1.getLanguage()));
        //h.setMargin(0,0,50,0);
        //Dialog.alert(song.getName());

        VerticalFieldManager vfm=new VerticalFieldManager();
        vfm.add(h);
        //vfm.add(new LabelField(song.getArtist()));
        row.add(vfm);
        contacts.addElement(row);
    }

    setSize( contacts.size());
}

// ListFieldCallback Implementation
public void drawListRow(ListField listField, Graphics g, int index, int y, int width) {
    listField.setRowHeight(index,107);
    CustomListField4 list = (CustomListField4) listField;
    TableRowManager rowManager = (TableRowManager) CustomListField4.contacts.elementAt(index);
    rowManager.drawRow(g, 0, y, width, list.getRowHeight());
}

public class TableRowManager extends Manager {
    public TableRowManager() {
        super(0);
    }   

Answer 1

You are calling getFieldWithFocus() which will give you the manager. You need to get the leaf field

protected void getValue4() {
   Field f = getLeafFieldWithFocus();
   if (f instanceof ListField) {
       //Your code
   }
}

Answer 2

I think your hierarchy of Field and Manager objects is incorrect, and this is causing problems with your detection of field focus/selection.

It wasn't obvious from the original code you posted, but by looking at your update, I assume that you are calling fetchAlbumsForLetter() once for every row. That's not right.

fetchAlbumsForLetter() is creating a new CustomListField4 each time it's called. And, CustomListField4 is a ListField.

A ListField is not meant to represent only one row. It's meant to represent all the rows. You should only create one instance of CustomListField4.

I would do either one of two things:

1. Continue to Use a ListField

If you want CustomListField4 to be a ListField (extends ListField), then in your implementation of

public void drawListRow(ListField listField, Graphics g, int index, int y, int width);

you should actually draw graphics objects, using all the Graphics#draw methods. These are primitive graphics items, like filled areas, lines, text, or bitmaps. You would not be using Field objects inside each ListField row, as you're trying to do with your TableRowManager class.

See here for a sample ListField, or here for a more sophisticated example

2. Imitate ListField with a Manager

change your code to

public class CustomListField4 extends VerticalFieldManager {

or

public class CustomListField4 extends Manager {

Then, you can use a TableRowManager for each row, and add LabelField or BitmapField objects to it.

See here for an example of this

---

If you fix these problems, then I think the way you are overriding navigationClick() will work fine for detecting the row click, and doing something with the selected row.

Answer 3

You can try this

 UiApplication.getUiApplication().invokeLater(new Runnable() {
                public void run() {
                    Dialog.alert(id+"");
                }
            });