fix

stmms-web/src/main/java/cn/com/qmth/stmms/admin/exam/PaperController.java

@@ -499,7 +499,8 @@ public class PaperController extends BaseExamController {
         ExamQuestion newQ = questionService.findByExamAndSubjectAndObjectiveAndMainNumberAndSubNumber(examId,
                 question.getSubjectCode(), question.isObjective(), question.getMainNumber(), question.getSubNumber());
         if (old == null
-                || ((old.getMainNumber() != question.getMainNumber() || old.getSubNumber() != question.getSubNumber()) && newQ != null)) {
+                || ((old.getMainNumber() != question.getMainNumber() || !old.getSubNumber().equals(
+                        question.getSubNumber())) && newQ != null)) {
             addMessage(redirectAttributes, "编辑失败，编辑题目不存在或编辑后的题号已存在");
             return "redirect:/admin/exam/paper/detail?subjectCode=" + question.getSubjectCode() + "&pageNumber="
                     + query.getPageNumber() + "&code=" + query.getCode() + "&category=" + query.getCategory()