处理NPE

ie-admin/src/main/java/com/ruoyi/web/service/LearnTeacherService.java

@@ -408,7 +408,7 @@ public class LearnTeacherService {
         dkCond.setExamineeTypes(examType);
         Map<String, LearnDirectedKnowledge> directedKnowledgeMap = learnDirectedKnowledgeMapper.selectLearnDirectedKnowledgeList(dkCond).stream().collect(Collectors.toMap(LearnDirectedKnowledge::getDirectKey, t -> t));
         LearnDirectedKnowledge directedKnowledge = null;
-        if(null != (directedKnowledge = getBestLearnDirectedKnowledge(curr, directedKnowledgeMap))) {
+        if(null != (directedKnowledge = getBestLearnDirectedKnowledge(curr, directedKnowledgeMap)) && StringUtils.isNotBlank(directedKnowledge.getKnowledges())) {
             knowledgeIdSet.addAll(Stream.of(directedKnowledge.getKnowledges().split(",")).map(t -> Long.parseLong(t.trim())).collect(Collectors.toList()));
         }
         return knowledgeIdSet;