Something unusual has occured to cause the driver to fail. NullPointerException

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От Larry Rogers
Тема Something unusual has occured to cause the driver to fail. NullPointerException
Дата
Msg-id 01090919033602.08247@localhost.localdomain
обсуждение исходный текст
Ответы Re: Something unusual has occured to cause the driver to
Список pgsql-jdbc
Hi all,

I'm having trouble opening a database connection to a test database on a
fresh PostGreSQL 7.1.3 installation on RedHat 7.1 from the RPMs.  I have a
simple test class TestPostGreSQL that opens a connection, queries for all the
rows in a table and prints the results to standard output.  The driver file
is in the same directory as the java class, which I execute using

java -classpath .:jdbc7.1-1.2.jar TestPostGreSQL

I get the following error message:

Something unusual has occured to cause the driver to fail. Please report this
exception: Exception: java.lang.NullPointerException
Stack Trace:
java.lang.NullPointerException
    at org.postgresql.Connection.openConnection(Connection.java:148)
    at org.postgresql.Driver.connect(Driver.java:122)
    at java.sql.DriverManager.getConnection(DriverManager.java:517)
    at java.sql.DriverManager.getConnection(DriverManager.java:177)
    at TestPostGreSQL.main(TestPostGreSQL.java:17)
End of Stack Trace

I created the database using

createdb testdb

and from psql created the table as

create table Person (
FirstName char(30) not null,
LastName char(30) not null);

then created the user and password and granted all permissions on the Person
table.

I start the server with

postmaster -i

to get TCP/IP support.  The code for the test class is at the end of this
message.  Note that everything is commented out except for loading the driver
and opening a connection.  I have used JDBC successfully for months with
Microsoft SQL Server, but I'm anxious to switch over to PostGreSQL!

Thanks in advance for any help!
Larry Rogers

*****************************

import java.sql.*;
import java.util.Date;

public class TestPostGreSQL {

    public static void main(String[] args) {

        final String driver = "org.postgresql.Driver";
        final String url = "jdbc:postgresql://localhost:5432?database=testdb";
        final String login = "TestUser";
        final String password = "TestPass";
        String sql = "SELECT * FROM Person";

        try {
            Class.forName(driver);
            Connection connection
                = DriverManager.getConnection(url, login, password);
            /*

            Statement statement = connection.createStatement();
            ResultSet result = statement.executeQuery(sql);

            while (result.next()) {
                System.out.println(result.getString("FirstName") + " " +
result.getString("LastName"));
            }
            result.close();
            statement.close();
            */
            connection.close();

        } catch(SQLException e) {
            System.out.println(e);
        } catch(ClassNotFoundException e) {
            System.out.println(e);
        }
    }
}

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