RE: Postgresql JDBC errors - Mailing list pgsql-interfaces

Which line is line 25 exactly?

Technically after the executeQuery(), rs may be null, so you should wrap
the next two lines in an if statement. ie:

rs = stmt.executeQuery("SELECT * FROM LE_TUTORIAL_DISCS");
if(rs) {  rs.next();  System.out.println("Title = " + rs.getString("title") + " -- Artist =
" + rs.getString("artist"));  rs.close(); // note to close the ResultSet
}

Peter

-- 
Peter Mount
Enterprise Support
Maidstone Borough Council
Any views stated are my own, and not those of Maidstone Borough Council.



-----Original Message-----
From: Nick Rathke [mailto:render@uswest.net]
Sent: Tuesday, April 18, 2000 5:17 AM
To: pgsql-interfaces@postgresql.org
Subject: [INTERFACES] Postgresql JDBC errors


I an using Postgresql-6.5.3 with jdbc6.5-1.2 and jdk1.2.2 on redhat
linux 6.2 . I
have tried to check the jdbc link using JDBCtest.java. Here is the info.

my classpath is

CLASSPATH=/lib/jdbc6.5-1.1.jar

JDBCtest.java

/*   This file is part of the tutorial in Chapter 3 of "Getting Started
with Enhydra".   It is not meant to be used in any other context.
   Simple program to test JDBC connectivity.  Assumes you have created
and populated   a table called LE_TUTORIAL_DISCS in your database.   Edit the connection string in the call to
DriverManager.getConnection()/

*/

import java.sql.*;
public class JDBCTest {public static void main( String[] args ) { Connection con  = null; Statement  stmt = null;
ResultSet rs   = null;
 
// Load the driver, get a connection, create statement, run query, and
print. try {  Class.forName("postgresql.Driver");  // Replace parameters below your database connection string,
username, and password  con = DriverManager.getConnection("jdbc:postgresql:dbtest"
,"appserver", "appserver" );  stmt = con.createStatement();  rs = stmt.executeQuery("SELECT * FROM LE_TUTORIAL_DISCS");
rs.next();  System.out.println("Title = " + rs.getString("title") + " -- Artist =
 

" + rs.getString("artist")); } catch(ClassNotFoundException e) {  System.err.println("Couldn't load the driver: " +
e.getMessage());} catch(SQLException e) {  System.err.println("SQLException caught: " + e.getMessage()); }}
 
}

which gives me the errors:

Exception in thread "main" java.lang.NullPointerException:                                   at
postgresql.jdbc2.ResultSet.getString(ResultSet.java:148)                                   at
postgresql.jdbc2.ResultSet.getString(ResultSet.java:531)                                   at
JDBCTest.main(JDBCTest.java:25)

I don't know enough about Java or databases to make any sense of this.
Any help would be great.

Nick Rathke