Question

我正在使用JPA查询获取值，并在我尝试将实体转换为DTO时将结果放在List但服务类中。我收到错误“Ljava.lang.Object;无法转换为entityClass” ...我试过forloop，forEach循环和迭代器得到错误。当我尝试获取第一个元素并将其放入entityclass对象时，我得到了这个错误。

List<Dashboard> dashboard = (List<Dashboard>)dashboardRepository.findAll();

    System.out.println("AllSolCount Length :------------------------------- "+dashboard.size());
    List<DashboardDto> result = new ArrayList<DashboardDto>();
    System.out.println("List Elements :----------------------------------- "+dashboard);
    /*for(int i=0;i<dashboard.size();i++) {
        **Dashboard obj = (Dashboard)dashboard.get(i); //error in this line I get** 
        DashboardDto dashboardDto = mapToDto(obj, DashboardDto.class, false);

        result.add((DashboardDto) dashboardDto);    
    }

    for (Dashboard obj : dashboard){
        **DashboardDto dashboardDto = mapToDto(obj, DashboardDto.class, false);// error in this line I get**
        result.add((DashboardDto) dashboardDto);
    }*/

    Iterator itr = dashboard.iterator();
    while(itr.hasNext()){
        **Dashboard obj = (Dashboard) itr.next(); // error here itself**

    }

    return result;

double *中的行是每个循环弹出错误的行。请提供建议

Image contains the resultset which is a list of entity class object but i am not able to type cast to enitity Class itself

从DB中检索数据时，我正在返回实体类的列表，但不是实体类的列表，而是获取java对象的列表..所以我假设可能是某些配置或缺少某些东西..

对我来说是一个自定义查询 @Query（value =“SELECT sol.offering，sol.state，COUNT（sol.id）FROM Solution sol GROUP BY sol.offering，sol.state”） public List findAll（）;

Answer 1

list（）方法返回List，你不能像你那样直接投射它们。

List<Dashboard> dashboard = (List<Dashboard>)dashboardRepository.findAll();

您必须存储在List<Object[]>并逐个迭代List<Object[]>，然后转换为List<Dashboard>。

List<Object[]> list= (List<Object[]>)dashboardRepository.findAll();
List<Dashboard> mylist=new ArrayList<>();

            if(list!=null){
            for(Object [] ob:list){
                member1=ob[0];
                member2=ob[1];
                .......
                Dashboard db=new Dashboard(menber1,member2...);//or you use setter method for class member initialize.
                mylist.add(db);
            }
        }

[Ljava.lang.Object;无法强制转换为entityClass

1 个答案: