Operation not allowed after ResultSet closed

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Operation not allowed after ResultSet closed

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#1 by (0 votes)
#2 by (0 votes)

1

I'm having a problem with a method whose function is to return a list of messages sent by the user (assuming the user is an attribute of the method class)

The code in question is the following:

private final String url = "jdbc:mysql://localhost:3306/mensajeria";
private final String driver = "com.mysql.jdbc.Driver"; 

public List<Mensaje> verMensajesEnviados() {
    List<Mensaje> mensajes = new LinkedList<>();

    iniciarConexion();
    if (conexion != null && usuario != null) {
        try {
            try (Statement st = conexion.createStatement()) {
                String consulta =
                        "SELECT * FROM mensajes WHERE de='" + 
                            usuario.getEmail() + "'";
                try (ResultSet res = st.executeQuery(consulta)) {
                    while (res.next()) {
                        Usuario u = getMsgPara(res.getString("para"));
                        if (u != null) {
                            String texto = res.getString("texto");
                            Mensaje msg = new Mensaje(usuario, u);
                            msg.setCuerpo(texto);
                            mensajes.add(msg);
                        }
                    }
                }
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Mensajes Enviados!!");
        } finally {
            finalizarConexion();
        }
    }
    return mensajes;
}

public Usuario getMsgPara(String email) {
    Usuario u = null;
    iniciarConexion();
    if (conexion != null) {
        try {
            try (Statement st = conexion.createStatement()) {
                String selectSQL =
                        "SELECT * FROM mensajes WHERE para='" + email + "'";
                try (ResultSet res = st.executeQuery(selectSQL)) {
                    if (res.next()) u = getUsuario(email);
                }
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Usuario!!");
        } finally {
            finalizarConexion();
        }
    }
    return u;
}

public Usuario getUsuario(String email) {
    Usuario u = null;
    iniciarConexion();
    if (conexion != null) {
        try {
            Statement st = conexion.createStatement();
            String selectSQL = 
                "SELECT * FROM usuarios WHERE email='" + email + "'";
            ResultSet res = st.executeQuery(selectSQL);
            while (res.next()) {
                String nombre = res.getString("nombre");
                String apellidos = res.getString("apellidos");
                String pwd = res.getString("password");

                u = new Usuario(nombre, apellidos, email, pwd);
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Usuario!!");
        } finally {
            finalizarConexion();
        }
    }
    return u;
}

private void iniciarConexion() {
    if (conexion == null) {
        try {
            Class.forName(driver);
            conexion = DriverManager.getConnection(url, "root", "");
        } catch (ClassNotFoundException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Conexion 1!!");
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Conexion 2!!");
        }
    }
}

private void finalizarConexion() {
    if (conexion != null) {
        try {
            conexion.close();
            conexion = null;
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Desconexion!!");
        }
    }
}

The problem is that I always throw the exception

Operation not allowed after ResultSet closed. >>> Error de Obtencion de Mensajes Enviados!!

I've been reviewing the code from top to bottom and I do not see what the problem is, I've been combing the internet looking to solve the problem but there's no way.

java jsp

asked by Álvaro Rojas 27.03.2017 в 17:01

source

2 answers

0

It may be because you are not closing the connection correctly, you may have a statement running at any given time, the best option is to close ( st.close () ) the first statement and execute the second.

answered by 27.03.2017 в 17:42

Label reference [closed] FireBase, Undefined symbols for architecture arm64

score 0 · Accepted Answer

The problem is that you have a Connection object that you reuse in the two methods getMsgPara and getUsuario. In both you initialize and close it, but always on the same instance.

The sequence would be:

getMsgTo: startConnection ()

getMsgFor: call to getUser

getUser: startConnection ()

getUser: finalize Connection ()

getMsgFor: you work with a Connection object already closed, and it gives the error.

The easiest thing you can do is to remove the Connection connection property from the class and reuse it and leave the code like this:

private Connection iniciarConexion() {
        try {
            Class.forName(driver);
            return DriverManager.getConnection(url, "root", "");
        } catch (ClassNotFoundException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Conexion 1!!");
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Conexion 2!!");
        }
}

private void finalizarConexion(Connection conexion) {
    if (conexion != null) {
        try {
            conexion.close();
            conexion = null;
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Desconexion!!");
        }
    }
}
public List<Mensaje> verMensajesEnviados() {
    List<Mensaje> mensajes = new LinkedList<>();

    Connection conexion = iniciarConexion();
    if (conexion != null && usuario != null) {
        try {
            try (Statement st = conexion.createStatement()) {
                String consulta =
                        "SELECT * FROM mensajes WHERE de='" + 
                            usuario.getEmail() + "'";
                try (ResultSet res = st.executeQuery(consulta)) {
                    while (res.next()) {
                        Usuario u = getMsgPara(res.getString("para"));
                        if (u != null) {
                            String texto = res.getString("texto");
                            Mensaje msg = new Mensaje(usuario, u);
                            msg.setCuerpo(texto);
                            mensajes.add(msg);
                        }
                    }
                }
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Mensajes Enviados!!");
        } finally {
            finalizarConexion(conexion);
        }
    }
    return mensajes;
}
public Usuario getMsgPara(String email) {
    Usuario u = null;
    Connection conexion = iniciarConexion();
    if (conexion != null) {
        try {
            try (Statement st = conexion.createStatement()) {
                String selectSQL =
                        "SELECT * FROM mensajes WHERE para='" + email + "'";
                try (ResultSet res = st.executeQuery(selectSQL)) {
                    if (res.next()) u = getUsuario(email);
                }
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Usuario!!");
        } finally {
            finalizarConexion(conexion);
        }
    }
    return u;
}

public Usuario getUsuario(String email, Connection conexion) {
    Usuario u = null;
        try {
            Statement st = conexion.createStatement();
            String selectSQL = 
                "SELECT * FROM usuarios WHERE email='" + email + "'";
            ResultSet res = st.executeQuery(selectSQL);
            while (res.next()) {
                String nombre = res.getString("nombre");
                String apellidos = res.getString("apellidos");
                String pwd = res.getString("password");

                u = new Usuario(nombre, apellidos, email, pwd);
            }
        } catch (SQLException ex) {
            System.out.println(ex.getMessage() + 
                    ". >>> Error de Obtencion de Usuario!!");
        } 
    }
    return u;
}