import java.sql.*;

public class DatabaseTestOne {
    public static void main(String[] args) {
        String url = "jdbc:oracle://127.0.0.1:8080";
        String username = "HR";
        String password = "samplepass";

        String sql = "SELECT EMPLOYEE_ID FROM EMPLOYEES WHERE LAST_NAME='King'";
        Connection connection;
        try {
            connection = DriverManager.getConnection(url, username, password);
            Statement statement = connection.createStatement();
            System.out.println(statement.execute(sql));
            connection.close();
        } catch (SQLException e) {
            System.err.println(e);
        }
    }
}

...
// jdbc:oracle:thin:@<hostname>:<port>:<sid>
String url = "jdbc:oracle:thin:@GalacticAC:1521:xe";
...

url="jdbc:oracle:thin:@localhost:1521:orcl"

jdbc:oracle:thin:@[HOST][:PORT]:SID

jdbc:oracle:thin:@//[HOST][:PORT]/SERVICE

jdbc:oracle:thin:@<hostName>:<portNumber>:<sid>;  (if you have sid)
jdbc:oracle:thin:@//<hostName>:<portNumber>/serviceName; (if you have oracle service name)

jdbc:oracle:<drivertype>:<username/password>@<database>

DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
connection = DriverManager.getConnection("jdbc:oracle:thin:@machinename:portnum:schemaname","userid","password");