Java Development

[flybirdtt]

This app i developed is a story reader. It has a screen  which contained a listfield. I hope after i can update the listfield.

May be just change one row of this listfield with specially index.

But i don't know how to implement it.

Now i just use the method like this:

for(int i=0;i<listfield.getSize();i++)

{

listfield.delete(0);

listfieldcallback.remove(0);

}

for(int i=0;i=Vecotr.size();i++)

{

listfield.insert(i);

listfieldcallback.insert(object,i);

}

then call this listfield manager: listfieldmanager.invalidate();

I think there should be have better way to update the specially rows of listfield

[BBDeveloper]

If you know the which List Row has to be removed or updated, Using the Index you can do it that time no need of using the for loop.

[flybirdtt]

Yes, I know the index. But how to update this listRow, I mean how to set the new value for this row.

And call listfield.invalidate(int index) to call the drawlist method from listfield callback.

Can you show me a example.

[BBDeveloper]

You know which index you have to update, remove that row from list and insert the new content to the same location. Is it not invalidating the change on Screen?

[flybirdtt]

I have tested like this.

 i use listfield.delete(0), and after that , i use listfield.insert(0). but this new listrow can not replace the old one .

For example: the size of a listfield is 10, and i delete(0), and insert(0). but even i use insert(0). The index of new row is not 0,the actual index is 10.

Sorry for my poor english.

Thanks very much for your reply.

[BBDeveloper · Accepted solution]

In your ListFieldCall back when you insert the new element it might just added to the Vector, Just give a look at the methods you are using.  You may have to use Vector.insertElementAt()..

[zany]

I think this sample will solve your problem

import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.container.MainScreen;

public class MySample extends UiApplication
{
    private MyScreen _fistScreen;

    public static void main(String[] args)
    {
        MySample instance = new MySample();
        instance.enterEventDispatcher();
    }

    public MySample()
    {
        _fistScreen = new MyScreen();
        invokeAndWait (new Runnable()
        {
            public void run()
            {
                pushScreen (_fistScreen);
            }
        });
    }
}

class MyScreen extends MainScreen
{
    public MyScreen ()

   {
        super();

        ListBox lstBox;

        setTitle ("My Screen");
        lstBox = new ListBox (20, "My Screen");
        lstBox.setEmptyString ("Test Empty String", DrawStyle.LEFT);
        lstBox.setCallback (lstBox);
        add (lstBox);
    }
}

class ListBox extends ListField implements ListFieldCallback
{
    private String _msg;
    private int _selectedRow;

    public ListBox (int noOfRows, String msg)
    {
        super (noOfRows);
        _selectedRow = -1;
        _msg = msg;
    }

    public int getPreferredWidth()
    {
        return 360;
    }

    public int getPreferredHeight()
    {
        return 480;
    }
   
    public void drawListRow (ListField lstField, Graphics g, int index, int y, int width)
    {
        String msg;

        msg = _msg;
        if ((_selectedRow != -1) && (index == _selectedRow))
            msg += " got selected";
        g.drawText (msg + " " + index, 0, y, 0, width);
    }

    public Object get (ListField lstField, int index)
    {
        return null;
    }

    public int getPreferredWidth (ListField lstField)
    {
        return 360;
    }

    public int indexOfList(ListField lstField, String prefix, int start)
    {
        return lstField.indexOfList (prefix, start);
    }

    protected boolean touchEvent (TouchEvent message)
    {
        switch (message.getEvent() )
        {
            case TouchEvent.CLICK:
                super.touchEvent (message);
                _selectedRow = getSelectedIndex();
                invalidate();
        }

        return false;
    }
}

[flybirdtt]

Thank you. I got it.

Thanks.

[BBDeveloper]

Thanks for updating us.