moving in a ResultSet

[kelvin cheung]

i have a GUI window which lets users to enter a staff number.
then it shows some data from the database.

when a user click on the button "next", it should show the next data
that matches the staff number (in other words, the data in the ResultSet).

here is my code :

 public ResultatVO nesteRad() throws SQLException  {
        try {
            rs.next();
            ResultatVO resultat = new ResultatVO(rs.getString(1), rs.getInt(2), rs.getString(3), rs.getString(4));
            return resultat;
        }
        
        catch (SQLException e) {
        System.out.println("Error");
        return null;}
        
    }
 

(ResultSet rs is defined as a global variabel in the same class)

the problem is that when i press "next", it does show the next data.
but when i then once again click "next" again,
nothing happens.

why is that?

[Avi Abrami]

Kelvin,
Method "next()" of interface "java.sql.ResultSet" returns a boolean. Perhaps you have reached the end of your "ResultSet". Also, your error handling code simply prints "Error" on the console. Since you are using a GUI, perhaps you forgot to look at the console to see if "Error" is getting displayed?

Perhaps your code should be something like:

public ResultatVO nesteRad() throws SQLException {
  ResultatVO resultat = null;
  try {
    if (rs.next()) {
      resultat = new ResultatVO(rs.getString(1),
                                rs.getInt(2),
                                rs.getString(3),
                                rs.getString(4));
    }
  }
  catch (SQLException e) {
    e.printStackTrace();
  }
  return resultat;
}

And remember to check the console for error messages.
Of-course, I think there are better ways of informing
the user (of your GUI application) that an error has
occurred, but I think that is beyond the scope of your
question. (Maybe you could try the Swing forum?)

Good Luck,
Avi.

[kelvin cheung]

Hello Avi,
I know that the that the next method returns a boolean ..
And I have tried to check the console. But cant see "error".

This is the code for the GUI button which calls the method which I posted earlier.

if (e.getSource()==btnNext) {
            System.out.print("Next is clicked");
            try {
            resultat = dao.nesteRad();
            if (resultat==null) {
            FoundNoRow();}
            else {
            showRow();}
            
            }
            catch (SQLException d) {
                System.out.println("Found no rows");
            }
        }  

These are the methods in the GUI class.

 public void FoundNoRow() {
    System.out.println("Found No Row");}
    
    public void showRow() {
        txtFag.setText(resultat.getFag());
            txtPoeng.setText(resultat.getPoeng()+"");
            txtDato.setText(resultat.getDato());
            txtKarakter.setText(resultat.getKarakter());
    } 

ResultatVO resultat; defined as global variabel.
Hmm?