ResultSet returns java.lang.nullpointerexception although the conculta has a result

I have a problem with a query:

    private void cargar(){                                    
        query = "select idcte from clientes where nombre like '" + str1 + "';";                                    
        res = conn.Consulta(query);                                    
        System.out.print(query);
    public class Conexion (){public ResultSet Consulta(String sql) {
        try {
            st = cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
            res = st.executeQuery(sql);
        } catch (SQLException ee) {
            JOptionPane.showMessageDialog(null, "Ocurrio un error, por favor consulte a su personal de sistemas");
            System.out.println("Error en la consulta: [" + sql + "]");
            System.out.println(ee.toString());
        }
        return (res);
    }}
}

public class Conexion (){public ResultSet Consulta(String sql) {
        try {
            st = cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
            res = st.executeQuery(sql);
        } catch (SQLException ee) {
            JOptionPane.showMessageDialog(null, "Ocurrio un error, por favor consulte a su personal de sistemas");
            System.out.println("Error en la consulta: [" + sql + "]");
            System.out.println(ee.toString());
        }
        return (res);
    }}

But when I try to print the query variable it enters an exception of nullpointerexception.

If I run the same query in mysql workbench, if it works for me

I already searched a lot in google, but I do not find anything similar ...