NullPointerException on PreparedStatement

[Peter Dennis]

Hi All,

Could someone please tell me what kind of conditions could cause the NullPointerException?

My code looks like this:

    
    public void populateComboBox(JComboBox cb)
    {
 
        DatabaseManager dbMgr = DatabaseManager.getInstance();
        Connection dbConnection = dbMgr.getConnection();
        
        PreparedStatement pStmt = null;
        ResultSet rs = null;
 
        MyComboBoxModel cm = (MyComboBoxModel) cb.getModel();
        cm.removeAllElements();
 
        try
        {
            pStmt = dbConnection.prepareStatement( // <--- Get NullPointerException HERE.
                "SELECT source_id, source_name FROM Source ORDER BY source_name");
 
            rs = pStmt.executeQuery();
 
            while (rs.next())
            {
 
                cm.addElement(
                    rs.getString("source_id"),
                    rs.getString("source_name"));
 
            }
 
            if (cm.isEmpty())
            {
                cm.addElement("-1", "None");
            }
 
        }
        catch (SQLException sqlex)
        {
            // do whatever
            sqlex.printStackTrace();
        }
        finally
        {
            DatabaseManager.closeStatement(pStmt, rs);
        }
 
    }
 

Many thanks,

Peter.

[Campbell Ritchie]

Welcome to JavaRanch

You are not getting an SQLException anywhere?
As you doubtless already know, NullPointerExceptions (NPEs) are very common and very annoying. I seem to write about them all the time, most recently here (note there is a mistake which I picked up later).

Are you sure your connection isn't null?

I presume the SQL is correct; it looks all right, and it would produce an SQLException rather than an NPE.

Go through what I wrote, and add a line just before where you get your Exception which prints whether the connection is null. See whether that helps.

I probably can't help any more now; it is too late, but there will be other people around.

[Peter Dennis]

Thanks very much for that. The null connection was the problem.

[Campbell Ritchie]

You're welcome. It was easy to guess from the info you provided.