Follow these steps:

1) Import the following packages in your java file:***

import java.sql.*;
import oracle.jdbc.driver.*;
import oracle.sql.*;

2) Load and Register the JDBC driver:***

DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

or you can use Class.forName("oracle.jdbc.driver.OracleDriver");

3) Connect to database:***

a) If you are using oracle oci driver,you have to use:

Connection conn = DriverManager.getConnection("jdbc:oracle:oci8:
@oracle.world", "root", "root");

where oracle.world is the TNSNAMES entry and root is the username and password.

b) If you are using oracle thin driver,you have to use:

Connection conn = DriverManager.getConnection ("jdbc:oracle:thin:@localhost:3306:roseindia",
"root", "root");

where localhost is the host,3306 is the port, roseindia is the database and root is the username and password.

4) Querying the database:**

a)create statement:

Statement st = conn.createStatement();

b)write query and execute the query:

ResultSet rs = st.executeQuery("SELECT * from student");

5) Close the statement,resultset and connection:**

rs.close();
st.close();
conn.close();

Try the following code:

import java.sql.*;
import oracle.sql.*;
import oracle.jdbc.driver.*;

public class OracleExample {
public static void main (String[] args) {
try{
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection("jdbc:oracle:thin: @localhost:3306:Oracle", "rose", "rose");
Statement st = conn.createStatement();
ResultSet rs = sql_stmt.executeQuery("SELECT * from student");
String str = "";
while (rs.next())
{
System.out.println(rset.getInt(1)+" "+ rs.getString(2)+" "+ rset.getFloat(3)+"\n";
}
rs.close();
st.close();
conn.close();
}
catch(Exception e){}
}
}