Resultset Update in a Event !

Question

First i do the connect with mysql 4.1.11 and mysqlconnector 5.15..
url = "jdbc:mysql://" + server + "/dbname?user=user&password=pass";                         Class.forName("org.gjt.mm.mysql.Driver").newInstance();             connect = DriverManager.getConnection(url);                                     System.out.println(url);                             System.out.println("Connection successful");
then the i do a normal query
            query = "SELECT * FROM betriebe where ergebnis is null and " +                 "((wieder_am is not null and wieder_am<now() and mitarbeiter=" + mitarbeiter  +") or "+                 "(mitarbeiter is null and wieder_am is null)) ORDER BY wieder_am desc, last_call limit 1;";             rS = state.executeQuery(query);             rS.updateString("ID_NUMMER","blub");  // this is working at this point !!!!             rS.updateInt("mitarbeiter",mitarbeiter);    // this is working at this point !!!!             rS.updateRow();                                    // this is working at this point !!!
Now my problem. I got a button on my GUI which has a Listener with this method
void cmd_nichterledigt_actionPerformed(ActionEvent e)     {         ResultSet tmp;         try         {             SimpleDateFormat formatter = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss");             java.util.Date currentTime_1 = new java.util.Date();             String dateString = formatter.format(currentTime_1);             System.out.println(dateString);             rS.updateString("Memo", txt_memo.getText()); // Here the error happens !                         rS.updateNull("ergebnis");             rS.updateNull("wieder_am");             rS.updateNull("mitarbeiter");             rS.updateInt("Wiedervorlage",0);             rS.updateRow();           } } Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at com.mysql.jdbc.ResultSetImpl.findColumn(ResultSetImpl.java:1059) at com.mysql.jdbc.UpdatableResultSet.updateString(UpdatableResultSet.java:2487) at aokframe.modify(aokframe.java:995) at aokframe.cmd_nichterledigt_actionPerformed(aokframe.java:1889) at aokframe$1.actionPerformed(aokframe.java:421)
idk what i am doing wrong. My resultset must be closed somehow. But i coundn´t found my mistake. thx for any help.

Answer 1

Hi,
You really shouldn't be mixing GUI and JDBC code.
I am guessing you have closed or re-executed the statement which generated the resultset.
I suggest reading about the Data Access Object (DAO) design pattern to limit the scope of your resultset objects and to separate JDBC code from the rest of your application.
Good luck!