unable to connect to mysql server

[rhitam30111985]

hi all .. java/jdbc newbie here ... i cant seem to perform the most basic step for database connectivity using java . here is my code :

 
import java.sql.*;
 
   public class connect
   {
       public static void main (String[] args)
       {
           Connection conn = null;
 
           try
           {
               String userName = "myname";
               String password = "mypassword";
               String url = "jdbc:mysql:localhost";
               Class.forName ("com.mysql.jdbc.Driver").newInstance ();
               conn = DriverManager.getConnection (url, userName, password);
               System.out.println ("Database connection established");
           }
           catch (Exception e)
           {
               System.err.println ("Cannot connect to database server");
           }
           finally
           {
               if (conn != null)
               {
                   try
                   {
                       conn.close ();
                       System.out.println ("Database connection terminated");
                   }
                   catch (Exception e) { /* ignore close errors */ }
               }
           }
       }
   }
 
 

when i am connecting to the same server using some other programming language such as python it is working perfectly fine .
what i cant figure out is what to assign to the "url" variable.. in other words .. how shall i determine the url of the company mysql server ? every time i run this code i get the same error "Cannot connect to database server".

I am using debian linux OS

any help appreciated,
regards
rhitam.

[r035198x]

Replace

System.err.println ("Cannot connect to database server");

on line 20 in your code with

e.printStackTrace()

That way you can see more information about the exception that is being thrown.

[rhitam30111985]

hi r035198x

i did as u said .. got the following errors :

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:169)
        at connect.main(connect.java:15)
 

cant figure what it means

[r035198x]

hi r035198x

i did as u said .. got the following errors :

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:169)
        at connect.main(connect.java:15)
 

cant figure what it means

That means the MySQL driver classes cannot be found by your program. You should add the MySQL connector jar file's path to your program's classpath.

[rhitam30111985]

uh.. how exactly do i do that ?

[r035198x]

uh.. how exactly do i do that ?

Do you have the MySQL driver .jar file with you?

[rhitam30111985]

i have already installed the jdbc driver for mysql.. namely

libmysql-java

but when i search for it using the following command :

whereis libmysql-java

it shows blank

[r035198x]

i have already installed the jdbc driver for mysql.. namely

libmysql-java

but when i search for it using the following command :

whereis libmysql-java

it shows blank

Download the connector .jar from here and add it to your classpath.

[rhitam30111985]

ok i downloaded and extracted the following file :

mysql-connector-java-3.0.17-ga.tar.gz

now by adding it to classpath do u mean just copy and paste it there? in that case how do i determine what is the classpath?

thanks

[ajos]

ok i downloaded and extracted the following file :

mysql-connector-java-3.0.17-ga.tar.gz

now by adding it to classpath do u mean just copy and paste it there? in that case how do i determine what is the classpath?

thanks

Now that you have got the mysql-connector-java-3.0.17-ga.tar.gz link just unzip the file, it contains a mysql-connector-java-3.0.17--bin which is a jar file, put the copy of the jar file in the lib folder of the application and include the path of the jar file in the class path. For more information read the mysql connector docs, it has everything that you need.
regards,
ajos

[rhitam30111985]

Hi all , sorry for making this topic active again but still facing problems ...

to add the jar file to classpath i did this :

downloaded the jar file and unipped it and placed in the following folder :

/home/rhitam/java/myprograms/

now to add to class path .. i have to first change the accessibilty of this jar file ... .

chmod +x /home/rhitam/java/myprograms/mysql-connector-java-3.0.17-ga-bin.jar

this worked ..
then .. i did this ...
set CLASSPATH=.;/home/rhitabrata/java/myprograms/mysql-connector-java-3.0.17-ga-bin.jar

it gave the error:


-bash: /home/rhitabrata/java/myprograms/mysql- connector-java-3.0.17-ga-bin.jar: cannot execute binary file


the code is also located in the same location as the jar file ... ( /home/rhitam/java/myprograms/)

what to do ?