Problems iterating results from a SQL JPA Native Query

Question

I am iterating the objects obtained from a Native SQL query to be able to print the propierties of one entity. For this propose I am using the following code:

public<T> ArrayList exectuteStoreProcedure(String sqlQuery){
    setEntities();
    int colcount = 0;
    int rowcount = 0;
    int rowcounter = 0;

    ArrayList a = new ArrayList();
    try{

        Query query = em.createNativeQuery(sqlQuery);
        rowcount = query.getResultList().size();
        colcount = ((Class[]) query.getResultList().get(0)).length;  

        String [][] array = new String [rowcount][colcount];

        for (Iterator<String[]> rs = query.getResultList().iterator(); rs.hasNext();) {
            String[] obj = rs.next();
            String[] record = new String[colcount];
            System.arraycopy(obj, 0, record, 0, colcount);
            array[ rowcounter++] = (String[]) record;
        }


        a.add(array);

        }catch(Exception ex){
         et.rollback();
     }
    closeEntities();

    return a;

}

The execution fails throwing the following exception:

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Class;

After running the programme over debbug mode I found that the problem is with the declartion of (Class[]) on this command line:

colcount = ((Class[]) query.getResultList().get(0)).length;

I am wondering how I could get the column length. Does anyone know how? My entity is Idioma and it's composed by String palabra, String idioma and int wordID;

Thanks in advance!

Simone Gianni · Accepted Answer · 2014-09-02 18:12:36Z

1

The error say it all, that is not an array of Class, it's as array of Object. You can change your cast and use:

colcount = ((Object[]) query.getResultList().get(0)).length;

answered Sep 2, 2014 at 18:12

Simone Gianni

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