C:\>type Conn.java
import java.sql.*;
class Conn
{
public static void main (String args [])
  throws ClassNotFoundException,SQLException
{
// Class.forName ("oracle.jdbc.Driver.OracleDriver");
 DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
 System.out.println("Hello");
 Connection conn = DriverManager.getConnection
                     ("jdbc:oracle:oci8:@mika", "michel", "michel");
 System.out.println("Successfully connected with OCI driver");
 conn.close();
 conn = DriverManager.getConnection
          ("jdbc:oracle:thin:@localhost:1530:mika", "michel", "michel");
 System.out.println("Successfully connected with thin driver");
 conn.close();
}

}

C:\>javac Conn.java

C:\>java Conn
Hello
Successfully connected with OCI driver
Successfully connected with thin driver

C:\>set
CLASSPATH=.;C:\oracle\ora1024\jdbc\lib\classes12.zip
ORACLE_HOME=C:\oracle\ora1024
ORACLE_SID=MIKA
Path=C:\oracle\ora1024\jdk\bin;C:\oracle\ora1024\bin;C:\oracle\ora1024\lib;
C:\oracle\ora1024\OPatch;C:\Perl\bin\;C:\WINDOWS\system32;C:\WINDOWS;
windir=C:\WINDOWS