连接Java和Oracle数据库

Question

I am JAVA newbie and I am trying to connect my java code and oracle database, I followed some tutorial but it did not work. This is my code.

  package probasem;



import java.sql.*;

public class Jedan {

     public static void main(String[] args) {

         try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","hr","hr");

            Statement st = con.createStatement();
            String sql  = " select * from employees";
            ResultSet rs = st.executeQuery(sql);
                    while (rs.next())
                        System.out.println(rs.getInt(1) +  " "  + rs.getInt(2));

con.close();                        
        } catch (Exception e) {


            System.out.println(e);
        }

    }
}

It throws me an exception :
java.sql.SQLException: Fail to convert to internal representation

also when I change the local host to 3036 I get this :

java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection

Answer 1

Change the code to below:

System.out.println(rs.getInt(1) + " " + rs.getString(2)); 

As second column is firstname and is of type varchar2.

Further, i recommend using column names instead of column position as they make code less error prone like this:

rs.getString("firstname");