org.postgres.Driver类异常-初学者

Question

thanks for any help, I am a complete noob here but trying to learn. the below code is simply trying to create a connection to a database. I am getting this error back:

 java.lang.ClassNotFoundException: org.postgres.Driver at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at CreateDB.main(CreateDB.java:11) java.lang.ClassNotFoundException: org.postgres.Driver 

having researched online the solution i come across is to check the library is added to to build path. i can confirm that i have (I think). to do this i right clicked the prject -> Properties -> Java Build Path -> external JARS and navigated to the postgresql - 42.41.4..jar which is located in "...\\eclipse-workspace\\libraries\\" I can see that the library is added under referenced libraries within the project. not a clue now im stuck. any help is genuinely appreciated.

I am learning from here https://www.tutorialspoint.com/postgresql/postgresql_java.htm

import java.sql.Connection;
import java.sql.DriverManager;

public class CreateDB {
    public static void main(String Args[]) {
        Connection c = null;
        try {
            Class.forName("org.postgres.Driver");
            c = DriverManager.getConnection("jdbc.postgresql://localhost:1080/VEM", "postgres", "Diablo12" ); //creates connection with U&P
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println(e.getClass().getName() +": " + e.getMessage());
            System.exit(0);
        }
        System.out.println("Database opened successfully");
    }
}

Answer 1

The correct driver name is: org.postgresql.Driver . So your code should look like this:

import java.sql.Connection;
import java.sql.DriverManager;

public class CreateDB {
    public static void main(String args[]) {
        Connection c = null;
        try {
            Class.forName("org.postgresql.Driver");
            c = DriverManager.getConnection("jdbc.postgresql://localhost:1080/VEM", "postgres", "Diablo12" ); //creates connection with U&P
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println(e.getClass().getName() +": " + e.getMessage());
            System.exit(0);
        }
        System.out.println("Database opened successfully");
   }
}

The false driver name causes java to throw the ClassNotFoundException because the class with the passed name could not be found in the classpath. Since Java 6 the loading of the driver via Class.forName() is not needed any more, like a_horse_with_no_name pointed out in his comment.