Question

I encountered the following error when I was executing my application:

java.sql.SQLException: No value specified for parameter 1

What does it mean?

My UserGroup list in my dao:

public List<UsuariousGrupos> select(Integer var) {
    List<UsuariousGrupos> ug= null;
    try {
        conn.Connection();
        stmt = conn.getPreparedStatement("select id_usuario, id_grupo from usuarios_grupos where id_grupo ='" + var + "'");
        ResultSet rs = stmt.executeQuery();
        ug = new ArrayList<UsuariousGrupos>();
        while (rs.next()) {
            ug.add(getUserGrupos(rs));
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        conn.Disconnected();
    }
    return ug;
}

public UsuariousGrupos getUserGrupos(ResultSet rs) {
    try {
        UsuariousGrupos ug = new UsuariousGrupos(rs.getInt("id_usuario"), rs.getInt("id_grupo"));
        return ug;
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return null;
}

My get list of User groups in my managed bean:

public List<UsuariousGrupos> getListOfUserGroups() {
    List<UsuariousGrupos> usuariosGruposList = userGrpDAO.select(var2);
    listOfUserGroups = usuariosGruposList;
    return listOfUserGroups;
}

My JSF page:

 <p:dataTable var="usergroups" value="#{usuariousGruposBean.listOfUserGroups}">
     <p:column headerText="" style="height: 0" rendered="false">
         <h:outputText value="#{usergroups.id_grupo}"/>
     </p:column>

My data table is able to display the list of groups from the database. However, when I select an individual row within my data table, it takes some time for the application to establish connection with my database to display the selected result.

Also, it is weird that the application is able to display certain selected results quicker than others. Does it have anything to do with the Exception I pointed out at the beginning?

Error:

Disconnected
Connected!!
java.sql.SQLException: No value specified for parameter 1
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1075)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:929)
    at com.mysql.jdbc.PreparedStatement.checkAllParametersSet(PreparedStatement.java:2560)
    at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:2536)
    at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:2462)
    at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2216)
    at br.dao.UsuariousGruposDAO.select(UsuariousGruposDAO.java:126)
    at br.view.UsuariousGruposBean.getListOfUserGroups(UsuariousGruposBean.java:54)


SEVERE: Error Rendering View[/index.xhtml]
javax.el.ELException: /index.xhtml @61,99 value="#{usuariousGruposBean.listOfUserGroups}": Error reading 'listOfUserGroups' on type br.view.UsuariousGruposBean
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)

Answer 1

There is no such method as Connection() and getPreparedStatement() on java.sql.Connection.

conn.Connection();
stmt = conn.getPreparedStatement("select id_usuario, id_grupo from usuarios_grupos where id_grupo ='" + var + "'");

The conn is clearly a homegrown wrapper around JDBC code. Your particular problem is likely caused by the code behind the getPreparedStatement() method. It’s apparently appending a ? to the SQL string before delegating through to the real connection.prepareStatement() method.

You probably don’t want to hear this, but your JDBC approach is totally broken. This design indicates that the JDBC Connection is hold as a static or instance variable which is threadunsafe.

You need to totally rewrite it so that it boils down to the following proper usage and variable scoping:

public List<UsuariousGrupos> select(Integer idGrupo) throws SQLException {
    Connection connection = null;
    PreparedStatement statement = null;
    ResultSet resultSet = null;
    List<UsuariousGrupos> usuariousGrupos = new ArrayList<UsariousGrupos>();

    try {
        connection = database.getConnection();
        statement = connection.prepareStatement("select id_usuario, id_grupo from usuarios_grupos where id_grupo = ?");
        statement.setInt(1, idGrupo);
        resultSet = statement.executeQuery();

        while (resultSet.next()) {
            usuariousGrupos.add(mapUsuariousGrupos(resultSet));
        }
    } finally {
        if (resultSet != null) try { resultSet.close(); } catch (SQLException ignore) {}
        if (statement != null) try { statement.close(); } catch (SQLException ignore) {}
        if (connection != null) try { connection.close(); } catch (SQLException ignore) {}

    }

    return usuariousGrupos;
}

See also:

• How to declare a global static class in Java?

---

Unrelated to the concrete question, you’ve another problem. The following exception

javax.el.ELException: /index.xhtml @61,99 value=”#{usuariousGruposBean.listOfUserGroups}”: Error reading ‘listOfUserGroups’ on type br.view.UsuariousGruposBean

indicates that you’re doing the JDBC stuff inside a getter method instead of (post)constructor or (action)listener method. This is also a very bad idea because a getter can be called more than once during render response. Fix it accordingly.

See also:

• Why JSF calls getters multiple times