tns 12560 linux

MY_DB =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = your_host)(PORT = your_port))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = your_service_name)
    )
  )

ping your_host
telnet your_host your_port

lsnrctl status

lsnrctl start

sudo iptables -A INPUT -p tcp --dport your_port -j ACCEPT

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class OracleConnectionTest {
    public static void main(String[] args) {
        String url = "jdbc:oracle:thin:@your_host:your_port:your_service_name";
        String user = "your_username";
        String password = "your_password";

        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            System.out.println("Connected to the database!");
        } catch (SQLException e) {
            System.err.println("Failed to connect to the database.");
            e.printStackTrace();
        }
    }
}