Re: ResultSet next() throws Null Pointer Exception - Mailing list pgsql-general

captainmidgetdonkey@yahoo.com (Captain) wrote in message news:<3ccbfe01.0202181451.fb2d98a@posting.google.com>...
> Hello. Any help would be gratefully appricated.
>
> I'm using Postgres 7.1.3.  I have small test class. I have put a
> comment line where this class fails.
>
> import java.sql.*;
>
> class DBTest {
>
>     static {
>         try {
>             Class.forName("org.postgresql.Driver");
>         }
>         catch (Exception e) {
>             System.err.println("Terminated.  Could not load postgres
> driver :" + e);
>             System.exit(1);
>         }
>     }
>
>     private static Connection conn;
>     private static Statement stmt;
>     private static ResultSet rs;
>     private static String sql = "SELECT * FROM message";
>
>
>
>     public static void main(String[] args) {
>         if(args.length < 1) {
>             System.out.println("Usage: DBTest <database> [<sql
> statement>]");
>             System.exit(1);
>         }
>         if(args.length == 2)
>             sql = args[1];
>
>         try {
>             conn = DriverManager.getConnection("jdbc:postgresql:"+
> args[0],"user","");
>             stmt = conn.createStatement();
>         }
>         catch (SQLException sqle) {
>             System.err.println("Terminated. Could not create
> connection or statement :" + sqle);
>             System.exit(1);
>         }
>         catch(Exception e) {
>             System.err.println("Terminated. Could not create
> connection or statement :" + e);
>             System.exit(1);
>         }
>         try {
>             rs = stmt.executeQuery(sql);
>         }
>         catch (SQLException sqle) {
>             System.err.println("Terminated. Exception occured during
> query execution (" + sql +") :" + sqle);
>         }
>         finally {
>             try {
>                 rs.close();
>                 stmt.close();
>                 conn.close();
>             }
>             catch (Exception e) {
>                 System.exit(-1);
>             }
>         }
>         try {
>             ResultSetMetaData meta = rs.getMetaData();
>             System.out.println("Number of column :" +
> meta.getColumnCount());
>
>             if(rs.next()) { //THIS IS THE FAILURE LINE.  EXCEPTION
> THROWN IS NULL POINTER
>                 System.out.println(rs.getString(1));
>             }
>             /*
>             while(rs.next()) {
>                 System.out.println(rs.getString(1) + "  " +
> rs.getString(2) + "  " + rs.getString(3));
>             }
>             */
>             System.out.println("Ended without error");
>         }
>         catch (SQLException sqle) {
>             System.err.println("Terminated. SQLException occured
> during resultSet display :" + sqle);
>             sqle.printStackTrace();
>         }
>         catch(Exception e) {
>             System.err.println("Terminated. Exception occured during
> resultSet display :" + e);
>             e.printStackTrace();
>         }
>         finally {
>             try {
>                 rs.close();
>                 stmt.close();
>                 conn.close();
>             }
>             catch (Exception e) {
>                 System.exit(-1);
>             }
>         }
>     }
> }
>
> When this class is run, this is the output.
>
> Number of column :6
> Terminated. Exception occured during resultSet display
> :java.lang.NullPointerException
> java.lang.NullPointerException
>         at org.postgresql.jdbc2.ResultSet.next(Unknown Source)
>         at com.ecmarket.util.database.test.DBTest.main(Unknown Source)
>
> What I know. The statement does return a ResultSet. The ResultSet is
> not null when the rs.next() line is called.
>
> Can YOU see what I've missed or got wrong. Or maybe there is a bug in
> the driver itself and you know the fix or workaround.
>
> Thanks


**********
So, I'm a doofus!  I have a finally block that closes my resultset
before I call rs.next().  Thanks to anyone that did look at this, but
without the finally block closing the resultset it works fine.

Thanks, Captian.
**********