Question

Im new in java and SQL, Im repeating a problem that i don’t know how to avoid it:

assume i want to make two executeQuery, one inside the other in the getRequestsFromDB method i make the first executeQuery and in the second method isProfessionalHasThatProfession i make the second executeQuery:

 private Vector<ClientRequest> getRequestsFromDB() throws SQLException {
    Vector<ClientRequest> retVal = new Vector<ClientRequest>();
    ResultSet result = null;
    try {
        for (int i=0 ; i<_userBean.getProfession().length ; ++i ){
            result = _statement.executeQuery("SELECT * FROM "+_dbName+"."+CLIENTS_REQUEST_TABLE+" WHERE "+CLIENTS_REQUEST_T_PROFESSION+"='"+_userBean.getProfession()[i]+"'");               
            while(result.next()){ //HERE IN THE SECOND LOOP GETTING NULL EXCEPTION

                if(isProfessionalHasThatProfession(result.getString(CLIENTS_REQUEST_T_PROFESSION))){
                    retVal.add(cr);
                    ClientRequest cr = new ClientRequest
                            (result.getString(CLIENTS_REQUEST_T_CLIENT_ID), 
                            result.getString(CLIENTS_REQUEST_T_CITY),
                            result.getString(CLIENTS_REQUEST_T_DATE),
                            result.getString(CLIENTS_REQUEST_T_PROFESSION));
                }
            }
        }
    } catch (SQLException ex) {
        throw ex;
    }
    return retVal;
}

the second function:

private boolean isProfessionalHasThatProfession(String profession) throws SQLException {             
    ResultSet result = null;
    try {
        result = _statement.executeQuery("SELECT "+WORKER_PROFESSIONS_T_PROFESSION+" FROM "+_dbName+"."+WORKER_PROFESSIONS_TABLE+" WHERE "+WORKER_PROFESSIONS_T_PROFESSIONAL_ID+"='"+_userBean.getProId()+"'");
        while(result.next()){
            if(result.getString(1).equals(profession)){
                return true;
            }
        }
    } catch (SQLException ex) {
        throw ex;
    }
    return false;
}

in the second loop im getting a SQLException: “operation not allowed after ResultSet closed”, i have tried:
close in finally the result with result.close() but also i get exception null pointer exception.

i’m really don’t know how to deal with that, ideas?
Thank You!

Answer 1

youre reusing _statement (which i assume is global?) to get 2 different ResultSets, but then you return to the 1st ResultSet (in the outside function) after you got the 2nd (inside the inner function, which automatically closed the 1st) – try using 2 separate statements