Java中的ClassCast异常 [英] ClassCast Exception in java

问题描述

我在休眠状态下编写查询，而我的方法是:

Iam writing a query in hibernate and my method is:

public String a(Object[] selectedAlarmId,
            Object[] selecteddeviceID, String loggedInUser, String clientIp,
            String role) throws Exception {
        int result = 0;
        b grp = new b();
        try {

            Session hiberSession = HibernateSessionFactory.currentSession();
            Transaction transaction = hiberSession.beginTransaction();

            List deviceQueryList = null;

            String clauseAppender = ("select max(severity),devicenodeid  from AlarmMappingBean where devicenodeid in (:devicelist) group by devicenodeid");
            Query deviceQuery = hiberSession.createQuery(clauseAppender);
            deviceQuery.setParameterList("devicelist", selecteddeviceID);
            deviceQueryList = deviceQuery.list();
            Iterator<Object[]> iter = deviceQueryList.iterator();

            while(iter.hasNext()){              
                Object[] objAlarm = iter.next();
                System.out.println(objAlarm.length);
                System.out.println("Severity - > " + objAlarm[0]);
                System.out.println("Device Node ID - > " + objAlarm[1]);            
                Query updateMangedNode = hiberSession
                .createQuery("update ManagedNode  set highestSeverity =? where nodeId = ?");
                updateMangedNode.setParameter(0, objAlarm[0]);
                updateMangedNode.setParameter(1, Long.parseLong(objAlarm[1].toString()));               
                //updateMangedNode.executeUpdate();
            }
        //  Long[] deviceArray =(Long[]) selecteddeviceID; 
        Exception occurs here-->    Object[] devArray = (Long[]) selecteddeviceID;


            Query groupQuery = hiberSession
                    .createQuery("select groupId from b where nodeId in (:devicelist)");

              groupQuery.setParameterList("devicelist", devArray);

            List<ManagedNode> devicelist = new ArrayList<ManagedNode>();
            devicelist = groupQuery.list();
            if(!(devicelist.isEmpty() )){
            Iterator<ManagedNode> itergroup =devicelist.iterator(); 
            while(itergroup.hasNext()){
                ManagedNode objgroup = itergroup.next();                
                grp.updateGroupHighestSeverity(objgroup.getGroupId());
            }


            }
            transaction.commit();


        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        } finally {
            HibernateSessionFactory.closeSession();
        }
        return Integer.toString(result);
    }

此处selecteddeviceId的值为[1234,12345，null，null] 并从表b从b中选择nodeid in(设备列表)中选择groupid"进行查询，这里groupid的数据类型为int而nodeid为long

Here the selecteddeviceId has values as [1234,12345, null, null] and query from the table b "select groupid from b where nodeid in(devicelist)" here datatype of groupid is int and nodeid is long

这给了我classcast异常Ljava.lang.Object;不可能是 强制转换为[Ljava.lang.Long;

It is giving me classcast exception as Ljava.lang.Object; cannot be cast to [Ljava.lang.Long;

我正在使用PostgresSQl

请帮助

推荐答案

来自您的代码:Object[] devArray = (Long[]) selecteddeviceID;

如果需要将已经是Object []的selecteddeviceID分配给Object []，为什么将它强制转换为Long []?

Why are you casting it to Long[] if you need to assign selecteddeviceID, which is already a Object[], to Object[]?

尝试执行此操作

 Long[] devArray = Arrays.copyOf(selecteddeviceID, selecteddeviceID.length, Long[].class)

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