When object is null

[Abid K]

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