Abid,
Hi,
I noted that you are adding the panel whether the data is null or not. I
would suggest you do this;
if (data!= null){
//construct and add the panel
}
On Tue, Jul 27, 2010 at 11:28 AM, Abid K <abz...@gmail.com> wrote:
> I hope someone can help a newbie who is learning Wicket.
>
> I have the following code which accepts a parameter and then does a
> database
> query to get the 'Data' object. If the user enters the wrong Id the
> database
> query will return null and in this case I want to notify the user the data
> could not be found and any other component should be hidden.
>
> But, when I get an null object the code stops working and a null exception
> is thrown, any ideas? Or is there a elegant way to do this?
>
> public class DataView extends WebPage {
>
> private Data data;
>
> public DataView(PageParameters parameters) {
> long dataId = parameters.getLong("dataId");
>
> DataDao dataDao = new DataDao();
> data = dataDao.getData( dataId );
>
> // display message that the data could not be found
> Label dataNotFound = new Label("dataNotFound", "Data could not be
> found");
> dataNotFound.setVisible(data == null);
>
> // otherwise display the panel containing the data
> SomePanel panel = new SomePanel("somePanel");
> panel.setVisible(data != null);
>
> add(dataNotFound);
> add(panel);
> }
>
> public class SomePanel extends Panel {
> public SomePanel(String id) {
> super(id);
> // this throws null exception when data is null
> Label label = new Label("someLabel", String.valueOf(data.getId()));
> add(label);
> }
> }
> }
>
> Thanks
>
