java.lang.ClassCastException : java. util.Vector 无法转换为我的类

Question

我使用 for 和查询来获取一些行，最后将所有这些行添加到一个类的一个 Arraylist 中。但我收到以下错误:

java.lang.ClassCastException: java.util.Vector cannot be cast to com.dominion.procop.agr.util.AGRSalvaguardasInforme
    at (pathofmyclass).mostrarInformeActivosAGR(AGRInformes.java:1130)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)

这些行是这些(标有 $ 的是 AGRInformes.java:1130):

            for (int i = 0; i < InformeAmenazasAGR.size()-1; i++) {
                String Amenaza = InformeAmenazasAGR.get(i).toString();
                Amenaza = Amenaza.substring(1,3);
                List<AGRSalvaguardasInforme> resultadoQuery = (List<AGRSalvaguardasInforme>) manager.SalvaguardaPorAmenaza(Amenaza);

                if(!resultadoQuery.isEmpty() ){                 
$                   for (AGRSalvaguardasInforme salvaguardaExtraida : resultadoQuery) {
                        InformeSalvaguardasAGR.add(salvaguardaExtraida);
                    }
                }                           
            }

这是 manager.SalvaguardaPorAmenaza() 方法(查询并返回对象):

public List<AGRSalvaguardasInforme> SalvaguardaPorAmenaza(String idAmenaza) {
    // SALVAGUARDAS POR ID_AMENAZA
        int dimension = 0;
        String consulta = "";   
        if(dimension!=0){   
            consulta = "SELECT COALESCE(MFT.ID_AMENAZA, MFA.ID_AMENAZA) as ID_AMENAZA, SAL.ID_SALVAGUARDA, SAL.DENOMINACION, SAL.DESCRIPCION, SAL.EFICACIA FROM AGR_SALVAGUARDAS SAL LEFT JOIN AGR_MIT_FREC_TIPO MFT "
                     + " ON SAL.ID_SALVAGUARDA = MFT.ID_SALVAGUARDA AND MFT.ID_AMENAZA = "+idAmenaza+" "
                     + " LEFT JOIN AGR_MIT_FREC_ACT MFA "
                     + " ON SAL.ID_SALVAGUARDA = MFA.ID_SALVAGUARDA AND MFA.ID_AMENAZA = "+idAmenaza+" "
                     + " WHERE MFT.ID_SALVAGUARDA IS NOT NULL OR MFA.ID_SALVAGUARDA IS NOT NULL GROUP BY SAL.ID_SALVAGUARDA, SAL.DENOMINACION, SAL.DESCRIPCION, SAL.EFICACIA, MFT.ID_AMENAZA, MFA.ID_AMENAZA";
        }else{
            consulta = "SELECT COALESCE(MFT.ID_AMENAZA, MFA.ID_AMENAZA) as ID_AMENAZA, SAL.ID_SALVAGUARDA, SAL.DENOMINACION, SAL.DESCRIPCION, SAL.EFICACIA FROM AGR_SALVAGUARDAS SAL LEFT JOIN AGR_MIT_FREC_TIPO MFT "
                     + " ON SAL.ID_SALVAGUARDA = MFT.ID_SALVAGUARDA AND MFT.ID_AMENAZA = "+idAmenaza+" "
                     + " LEFT JOIN AGR_MIT_FREC_ACT MFA "
                     + " ON SAL.ID_SALVAGUARDA = MFA.ID_SALVAGUARDA AND MFA.ID_AMENAZA = "+idAmenaza+" "
                     + " WHERE MFT.ID_SALVAGUARDA IS NOT NULL OR MFA.ID_SALVAGUARDA IS NOT NULL GROUP BY SAL.ID_SALVAGUARDA, SAL.DENOMINACION, SAL.DESCRIPCION, SAL.EFICACIA, MFT.ID_AMENAZA, MFA.ID_AMENAZA";
                }
            Query q = dao.createNativeQuery(consulta);
            List<AGRSalvaguardasInforme> resultado = q.getResultList();

            return resultado;
        }

为什么会出现这个错误以及如何正确管理？预先感谢您。

Answer 1

问题 1

命名困惑，请遵循java命名约定。

问题2

for (int i = 0; i < InformeAmenazasAGR.size()-1; i++) {

这样，List:InformeAmenazasAGR的最后一个元素永远不会被阅读。

问题3

 for (int i = 0; i < InformeAmenazasAGR.size()-1; i++) {
              ...
                        InformeSalvaguardasAGR.add(salvaguardaExtraida);
                 
                ...                           
            }

您正在 for 循环中将元素添加到列表中。将会导致难以预料的后果。如果您需要这样做，请使用 Iterator .

问题 4

如果你使用“NativeQuery”(我猜是jpa？).getResultList() ，你得到了 List<Object[]> ，您不能期望查询给您 List<YourClass> 。你必须深入研究结果，并自己完成工作。