Loading and connecting to mysql jdbc driver runtime

I have three questions before I answer to your issues:

1. Statement 1:

   ya, I have set the classpath of mysql jar in the environment variables, do we need to set it through system properties?

   Q1: Why are to relying on custom class loader, when a class is readily available to the System class loader from the class path?
   You don't need explicit class path to mysql***.jar to use custom class loader.

2. Statement 2:

   Class sqldriver = urlCl.loadClass("com.mysql.jdbc.Driver"); // Runtime loading
//Compilation failing as "sqldriver" class of type Driver is not found
Driver ds = (Driver) sqldriver.newInstance();

   Q2: Claiming Compilation failing ... is very conflicting. Is your compiler looking for such class to generate your class!?
   I am sure it is not. May be the error is at run time with a java.lang.ClassNotFoundException: com.mysql.jdbc.Driver. And I also suspect the comment should go with your Statement 3 below.
   If it is a CNFE, your file path to mysql***.jar is wrong. Fix it first.

3. Statement 3:

   //I am using now java.sql.Driver to remove the compilation error
//Runtime fail.. "Driver" Class not Found Exception. sqldriver = Class.forName("com.mysql.jdbc.Driver", true, sqldriver.getClassLoader()).newInstance();

   Q3: Claiming ... "Driver" Class not Found Exception is suspectful. Because, this statement won't get compiled. Then how can it be a Runtime fail. ..!?
   I also suspect the comment should go with your Statement 2 above.
   And here, you need to call newInstance() and then cast to java.sql.Driver before assigning to sqlDriver variable. Because Class.forName( ... only returns a Class object associated with the class or interface with the given string name.
   If issue at Statement 2 above is fixed, you can apply this fix to test further.

Let me hope you got these statements clarified.

I have a working sample code below, with a tested output shown for you.

import java.io.File; // and others as required public class MySQLDriveClassLoader { public static void main( String [] args ) throws Exception { //File f = new File( "/home/ravinder/soft-dump/mysql-connector-java-5.1.18-bin.jar" ); File f = new File( "E:\\Soft_Dump\\mysql-connector-java-5.0.4\\mysql-connector-java-5.0.4-bin.jar" ); URLClassLoader urlCl = new URLClassLoader( new URL[] { f.toURI().toURL() }, System.class.getClassLoader() ); Class mySqlDriver = urlCl.loadClass( "com.mysql.jdbc.Driver" ); //*** Start: DEBUG ************************* //mySqlDriver.con // On pressing CTRL+SPACEBAR, after .con, IDE shows "No default proposals" // meaning it still is not an instance of Driver, and hence can't call a method from Driver class. //Incompatible conditional operand types Class and Driver //System.out.println( mySqlDriver instanceof java.sql.Driver ) ); System.out.println( "mySqlDriver: " + mySqlDriver ); System.out.println( "Is this interface? = " + mySqlDriver.isInterface() ); Class interfaces[] = mySqlDriver.getInterfaces(); int i = 1; for( Class _interface : interfaces ) { System.out.println( "Implemented Interface Name " + ( i++ ) + " = " + _interface.getName() ); } // for(...) Constructor constructors[] = mySqlDriver.getConstructors(); for( Constructor constructor : constructors ) { System.out.println( "Constructor Name = " + constructor.getName() ); System.out.println( "Is Constructor Accessible? = " + constructor.isAccessible() ); } // for(...) //*** End : DEBUG ************************* Driver sqlDriverInstance = ( Driver ) mySqlDriver.newInstance(); System.out.println( "sqlDriverInstance: " + sqlDriverInstance ); Connection con = null; try { /****************************************************************** // You may fail to register the above driver // hence don't depend on DriverManager to get Connected //DriverManager.registerDriver( sqlDriverInstance ); //Driver driver = DriverManager.getDriver( "com.mysql.jdbc.Driver" ); // ( "jdbc:mysql" ); Enumeration<Driver> enumDrivers = DriverManager.getDrivers(); while ( enumDrivers.hasMoreElements() ) { Driver driver = enumDrivers.nextElement(); System.out.println( "driver: " + driver ); } // while drivers //******************************************************************/ String dbUrl = "jdbc:mysql://:3306/test"; Properties userDbCredentials = new Properties(); userDbCredentials.put( "user", "root" ); userDbCredentials.put( "password", "password" ); // No suitable driver found for ... //con = DriverManager.getConnection( dbUrl, "root", "password" ); // safely use driver to connect con = sqlDriverInstance.connect( dbUrl, userDbCredentials ); System.out.println( "con: " + con ); Statement stmt = con.createStatement(); String sql = "select now()"; ResultSet rs = stmt.executeQuery( sql ); if ( rs.next() ) { System.out.println( rs.getString( 1 ) ); } // if rs } catch( Exception e ) { e.printStackTrace(); // only for quick debug } finally { try { if ( con != null ) con.close(); } catch ( Exception ignoreThis ) {} } } // psvm(...) } // class MySQLDriveClassLoader 

A successful compilation and run, resulted following output:

mySqlDriver: class com.mysql.jdbc.Driver Is this interface? = false Implemented Interface Name 1 = java.sql.Driver Constructor Name = com.mysql.jdbc.Driver Is Constructor Accessible? = false sqlDriverInstance: com.mysql.jdbc.Driver@1270b73 con: com.mysql.jdbc.Connection@32fb4f 2012-05-29 03:52:12.0 

DriverManager ignores classes loaded at runtime, it will work only for classes loaded by the System class loader.

You can create a Dummy driver class which encapsulates your actual database driver. Source code can be found here.

Off topic:

File.toURL is deprecated, instead get URL from File using toURL on URI

URLClassLoader urlCl = new URLClassLoader(new URL[] { f.toURI().toURL()},System.class.getClassLoader());