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@ontko.com or nick@fankhausers.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@pereira.com   |
>        / (_/ _ \__    [Math|99]-IMECC       |
> _______\____/_\___)___Unicamp_______________/
>
>
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