List集合中的对象判断某个字段是否重复

  public static void main(String[] args) {
    //判断是否有重复的问题添加
    List<HealthQuestionInfoReq> healthQuestionInfoReqs = new ArrayList<>();
    HealthQuestionInfoReq healthQuestionInfoReq1 = new HealthQuestionInfoReq();
    HealthQuestionInfoReq healthQuestionInfoReq2 = new HealthQuestionInfoReq();
    healthQuestionInfoReq1.setQuestionName("123");
    healthQuestionInfoReq2.setQuestionName("123");
    healthQuestionInfoReqs.add(healthQuestionInfoReq1);
    healthQuestionInfoReqs.add(healthQuestionInfoReq2);
    HashSet<String> uidSet = new HashSet<>(); //这里泛型里面的类型和你需要判断是字段类型一致
    healthQuestionInfoReqs.stream().forEach(t->{
      uidSet.add(t.getQuestionName());
    });
    //如果为true说明不相等，如果为false则为相等
    System.out.println( healthQuestionInfoReqs.size() == uidSet.size());
  }

 附上：List集合差集(基于java8新特性)

* 求List1中有的但是List2中没有的元素

    public static List<String> subList2(List<String> list1, List<String> list2) {
        Map<String, String> tempMap = list2.parallelStream().collect(Collectors.toMap(Function.identity(), Function.identity(), (oldData, newData) -> newData));
        return list1.parallelStream().filter(str -> {
            return !tempMap.containsKey(str);
        }).collect(Collectors.toList());
    }