从迭代器next方法获取ClassCastException

Question

List<CustomerList> aaData = customerlistDaoimpl.getCustomerList();

/*
 * putting data in a JSON form that DataTables recognizes
 */
String data = "{\"sEcho\": 3, \"iTotalRecords\": " + count + ",\"iTotalDisplayRecords\": " + count + ",\"aaData\": [ ";
Iterator<CustomerList> itr = aaData.iterator();
while(itr.hasNext()){
    CustomerList cl = (CustomerList) itr.next();
    data += "[\"" + cl.getName() + "\",\"" + cl.getAddress() + "\",\"" + cl.getZipcode() + "\",\"" + 
    cl.getPhone() + "\",\"" + cl.getCity() + "\",\"" + cl.getCountry() + "\",\"" + cl.getNote() + "\" ] ";
    count++;
}
data += "]}";

@SuppressWarnings("unchecked")
@Override
public List<CustomerList> getCustomerList() {
    List<CustomerList> cuList = null;
    Session session = null;

    try{
        session = sessionfactory.openSession();
        session.beginTransaction();         
        cuList = session.createSQLQuery("select * from customer_list").list();      
        session.getTransaction().commit();
    }catch (RuntimeException e){
        System.out.println(e.getMessage());
    }
    finally
    {
        if(session != null){
            session.close();                
        }
    }

    return cuList;
}

回溯的痕迹

对于路径[/sptestjs]的上下文中的servlet[sptestjs]的servlet.servelet.service（）抛出异常[请求处理失败；嵌套异常是java.lang.ClassCastException:[ljava.lang.Object；无法强制转换为根原因java.lang.ClassCastException:[ljava.lang.Object；无法强制转换为com.sptestjs.implementation.CustomerList；无法强制转换为com.sptestjs.implementation.Controller.homeController.getCustomerList（Sun.Reflect.DelegatingMethodAccessorImpl.Invoke（未知源）

我确实找到电话了

SQLQuery cuSQLQuery = session.createSQLQuery("select * from customer_list");

返回一个SQLQuery实例，其列表类型为对象元素的ArrayList,其中

Query cuQuery = session.createQuery("from customer_list");

返回null。

Answer 1

从迭代器next方法获取ClassCastException

这意味着您AADATA实际上不是列表 您在错误地更改其类型的地方有类型擦除。如果您仔细查看ClassCastException，它会告诉您组件类型到底是什么。

ClassCastException:[Ljava.lang.Object；不能强制转换为com.sptestjs.implementation.customerList

List<Object[]> cuList = session.createSQLQuery("select * from customer_list").list();