Question

我有一个TicketBooking类型的List，我将其设置为responseObject。当我尝试获取列表并转换回TicketBooking类型时，它会抛出ClassCastException。这是我的代码

 List<TicketBooking> bookingDetailList = new ArrayList<TicketBooking>();
    bookingDetailList.add(booking);
    if(Utils.isNotNull(oldBooking)) 
        bookingDetailList.add(oldBooking);
    respObj.setObject(bookingDetailList);

从这个方法我返回respObj。

在调用方法

中

    List bookingList = new ArrayList();
    bookingList.add(Arrays.asList(respObj.getObject()));
    booking = (TicketBooking) bookingList.get(0);

抛出ClassCastException

请帮忙。

Answer 1

您需要在调用方法时创建TicketBooking列表。

你的代码

 List bookingList = new ArrayList();
 bookingList.add(Arrays.asList(respObj.getObject()));
 booking = (TicketBooking) bookingList.get(0);

应替换为

 List<TicketBooking> bookingList= new ArrayList<TicketBooking>();
 List list =  Arrays.asList(respObj.getObject());
 for(Object obj in list ){
    bookingList.add(obj);
    booking = bookingList.get(0);
 }

或以下将做同样的

   List bookingList = new ArrayList();
bookingList.addAll(Arrays.asList(respObj.getObject()));
booking = (TicketBooking) bookingList.get(0);

Answer 2

Arrays.asList(respObj.getObject())

这个表达式返回一个List对象，当然抛出ClassCasException

你应该

List list =  Arrays.asList(respObj.getObject());
for(Object obj in list){
      bookingList.add(obj);
}

Answer 3

将add()替换为addAll()

List bookingList = new ArrayList();
bookingList.addAll(Arrays.asList(respObj.getObject()));

如果使用add，它会将其视为实例（类型为List），因此第一个元素的类型为List，然后您尝试将其转换为TicketBooking }

Answer 4

List bookingList = new ArrayList();
bookingList.add(Arrays.asList(respObj.getObject()));//error is here
booking = (TicketBooking) bookingList.get(0);

我认为在bookingList中你添加了一个完整的List而不是一个TicketBooking对象。并且您期待TicketBooking对象。

您应该按照以下方式修改代码。

ArrayList<TicketBooking> bookingList= new ArrayList<TicketBooking>();
bookingList.addAll((ArrayList<TicketBooking>)respObj.getObject()); //Add all to add whole list
booking =  bookingList.get(0);

将ArrayList转换为Object数组

4 个答案: