如何解决java.lang.ClassCastException:对于hibernate中的query.list()

Question

我正在使用Hibernate执行select选项,Query正在执行但在query.list()方法中获得异常,

这是我的代码,

String hql="select a.vehicleno, a.lat, a.lng, a.status, a.rdate, a.rtime from LatitudeBean a, VehicleRegisterBean b where a.vehicleno=b.vehicleno and b.clientid= :clientId and b.groupid in(select groupid from GroupDetails where groupname= :groupname and clientid= :gdclientId)"; // valid query
Query query =sessio.createQuery(hql);
List<LatitudeBean> groupList = (List<LatitudeBean>)query.list(); //Here I am getting exception
for(LatitudeBean arr : groupList){
        System.out.println(arr.getVehicleno());
    }

例外是,

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.aurodisplay.its.beans.LatitudeBean
at com.abc.its.controller.LoginController.doPost(LoginController.java:83)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)

如何转换从list()方法返回的列表.任何人都可以帮助我.

Answer 1

问题是您的查询不选择实体,而只选择实体的属性.

因此,结果将不是实体列表,而是对象数组列表(哪些数组将保存所选属性).

试试这个:

List<Object[]> groupList = (List<Object[]>) query.list();
for(Object[] arr : groupList) {
    System.out.println("vehicleno: " + arr[0]);
}

或者,如果要选择整个实体,请按以下方式修改查询:

String hql = "select a from LatitudeBean a, VehicleRegisterBean b where ...";

这样你的原始代码就可以了.