Jakarta ee 如何将linkedlist从一个servlet传递到另一个servlet？当我运行它时，它会在listLeagues servlet中显示nullpointer异常

addLeagueServlet.java

    String leagueName = request.getParameter("name");
    int leagueYear = Integer.parseInt(request.getParameter("yearleague"));
    String leagueSeason = request.getParameter("season");

    League league = new League(leagueYear, leagueSeason, leagueName);
    leagueList.add(new League(leagueYear, leagueSeason, leagueName));
    request.setAttribute("leagueList", leagueList);
    out.print("League successfully added!<br>");
    out.print("<a href='Landing.jsp'>Home</a>");

---

因此，当我在jsp中单击leagues链接列表时，它会显示空指针异常。请告诉我如何将linkedlist从addleaguelist传递到listleagues servlet。谢谢。

您的代码输入错误。添加属性为“leagueList”。尝试以“leagueList”的形式检索

    Iterator iter = ((LinkedList)request.getAttribute("leaguelist")).iterator();
    League league = (League)iter.next();
    while(iter.hasNext())
    out.print(league.getName());