Re: [JDBC] JDBC isn't running

Marcelo,

It should be:

java HelloPostgresql

not

java HelloPostgresql.class

This was mentioned in at least one other email in this thread.

--Barry

Marcelo Pereira wrote:
> Hi again,
>
> I have configured the variable:
> CLASSPATH=/usr/local/pgsql/share/java/postgresql.jar:.
>
> and compiled (without errors) the following source code:
>
> // -- begin
> /**
> * A demo program to show how jdbc works with postgresql
> * Nick Fankhauser 10/25/01
> * nickf(at)ontko(dot)com or nick(at)fankhausers(dot)com
> * This program may be freely copied and modified
> * Please keep this header intact on unmodified versions
> * The rest of the documentation that came with this demo program
> * may be found at http://www.fankhausers.com/postgresql/jdbc
> */
>
> import java.sql.*; // All we need for JDBC
> import java.text.*;
> import java.io.*;
>
> public class HelloPostgresql
> {
> Connection db; // A connection to the database
> Statement sql; // Our statement to run queries with
> DatabaseMetaData dbmd; // This is basically info the driver delivers
> // about the DB it just connected to. I use
> // it to get the DB version to confirm the
> // connection in this example.
>
> public HelloPostgresql(String argv[])
> throws ClassNotFoundException, SQLException
> {
> String database = argv[0];
> String username = argv[1];
> String password = argv[2];
> Class.forName("org.postgresql.Driver"); //load the driver
> db = DriverManager.getConnection("jdbc:postgresql:"+database, username, password); //connect to the db
> dbmd = db.getMetaData(); //get MetaData to confirm connection
> System.out.println("Connection to "+dbmd.getDatabaseProductName()+" "+dbmd.getDatabaseProductVersion()+" successful.\n");
> sql = db.createStatement(); //create a statement that we can use later
>
> String sqlText = "create table jdbc_demo (code int, text varchar(20))";
> System.out.println("Executing this command: "+sqlText+"\n");
> sql.executeUpdate(sqlText);
>
> sqlText = "insert into jdbc_demo values (1,'One')";
> System.out.println("Executing this command: "+sqlText+"\n");
> sql.executeUpdate(sqlText);
>
> sqlText = "insert into jdbc_demo values (3,'Four')";
> System.out.println("Executing this command twice: "+sqlText+"\n");
> sql.executeUpdate(sqlText);
> sql.executeUpdate(sqlText);
>
> sqlText = "update jdbc_demo set text = 'Three' where code = 3";
> System.out.println("Executing this command: "+sqlText+"\n");
> sql.executeUpdate(sqlText);
> System.out.println (sql.getUpdateCount()+" rows were update by this statement\n");
>
> System.out.println("\n\nNow demostrating a prepared statement...");
> sqlText = "insert into jdbc_demo values (?,?)";
> System.out.println("The Statement looks like this: "+sqlText+"\n");
> System.out.println("Looping three times filling in the fields...\n");
> PreparedStatement ps = db.prepareStatement(sqlText);
> for (int i=10;i<13;i++)
> {
> System.out.println(i+"...\n");
> ps.setInt(1,i); //set column one (code) to i
> ps.setString(2,"HiHo"); //Column two gets a string
> ps.executeUpdate();
> }
> ps.close();
>
>
> System.out.println("Now executing the command: "+"select * from jdbc_demo");
> ResultSet results = sql.executeQuery("select * from jdbc_demo");
> if (results != null)
> {
> while (results.next())
> {
> System.out.println("code = "+results.getInt("code")+"; text = "+results.getString(2)+"\n");
> }
> }
> results.close();
>
>
> sqlText = "drop table jdbc_demo";
> System.out.println("Executing this command: "+sqlText+"\n");
> sql.executeUpdate(sqlText);
>
> db.close();
> }
>
> public static void correctUsage()
> {
> System.out.println("\nIncorrect number of arguments.\nUsage:\n "+"java \n");
> System.exit(1);
> }
>
> public static void main (String args[])
> {
> if (args.length != 3) correctUsage();
> try
> {
> HelloPostgresql demo = new HelloPostgresql(args);
> }
> catch (Exception ex)
> {
> System.out.println("***Exception:\n"+ex);
> ex.printStackTrace();
> }
> }
> }
> // -- end
>
> $ javac HelloPostgresql.java
> $ java HelloPostgresql.class
> Exception in thread "main" java.lang.NoClassDefFoundError: HelloPostgresql/class
>
> Where am I going wrong?? I have Java (J2SDK) and Ant
> (Jakarta-Ant) configured properly, and postgresql (7.3.1) was configured
> with ``--with-java'' option.
>
> I have created a table on postgresql, with some fields, to test this code,
> but when I run it crashes instantly with the message above.
>
> The driver (postgresql.jar) was compiled and I have set CLASSPATH as
> above. Why doesn't it code run?
>
> Thanks in advance and
> Best Regards,
>
> Marcelo Pereira
>
> -- Remember that only God and ^[:w saves.
> __
> (_.\ © Marcelo Pereira |
> / / ___ marcelo(at)pereira(dot)com |
> / (_/ _ \__ [Math|99]-IMECC |
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>
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