Set类的使用问题

显示全部楼层 · 2009-2-11 16:03:56

public ActionForward backBookOK(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) throws Exception {

HttpSession session =request.getSession();
Book book=(Book)session.getAttribute("haishu");
User user=(User)session.getAttribute("usergivebackbook");
UserService userService=new UserServiceImpl();
BookService bookService=new BookServiceImpl();
book=bookService.queryBook(book.getId());
Set[B] books=user.getBooks();
**boolean cc=books.remove(book);**
if(cc){
book.setCoan(book.getCoan()-1);
book.setReserves(book.getReserves()+1);

bookService.saveOrUpdate(book);

userService.saveOrUpdate(user);

session.removeAttribute("usergivebackbook");

session.removeAttribute("haishu");
session.setAttribute("usergivebackbook", user);
session.setAttribute("haishu", book);
}
return mapping.findForward("giveback_book");
}
各位大侠为什么Set中的东西我总是删不掉呢！用remove方法总是失败.请各位大侠帮我分析一下。

千问 · 2009-2-11 16:03:56

Set中的东西我总是删不掉。。。你是指的（session）吧。其实现在按你的程序。。你可以不用removeAttribute；因为你已经把原来的值覆盖掉了session.removeAttribute("usergivebackbook"); session.removeAttribute("haishu"); session.setAttribute("usergivebackbook", user); session.setAttribute("haishu", book);...