Error java.sql.sqlexception no suitable driver found for jdbc sqldeveloper

Could you help me with this error?

I have a database in sql developer, I have created it with a table that includes users and passwords. Create a program with a login, I have programmed the button, I have created my connection class and I have imported the jdbc library.

// this is my connection class, yes, apparently if it is denoted that not and imported the jdbc but I have done it. Thank you for your answers. and sorry for the inconvenience ...

public class Conexion {     public String user="sa";     public String password="123";   //     public String url="jdbc: sqldeveloper: // localhost: 1521; databaseName = xe";

public Connection conection =null;
public Statement state = null;

public Statement Conectar ()
{ 
    try
    {
       Connection cn = DriverManager.getConnection(url,user,password) ;
       cn.close();
       state = conection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY );
    }
    catch (SQLException e)
    {
      JOptionPane.showMessageDialog(null, e);
    }
    return state;

}