解释<% for(Map map : list){ %> <%=map.get("count")%>, <% } %>

As an AI language model, I am programmed to understand the concept of null, which refers to the absence of a value or a variable that has not been assigned a value. In programming, null is often used to indicate that a variable or object is not available or does not exist.

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优化这段代码：List<CompletableFuture<CallIntersectionVo>> futureList = Lists.newArrayList(); for (Map.Entry<String, List<String>> entry : intersectionResult.entrySet()) { CompletableFuture<CallIntersectionVo> future = CompletableFuture.supplyAsync(() -> { String account = entry.getKey(); List<String> personNoList = entry.getValue().stream().distinct().collect(Collectors.toList()); CallIntersectionVo vo = new CallIntersectionVo(); if (personNoList.size() >= 2) { List<PersonBasicVo> personVoList = Lists.newArrayList(); int count = 0; for (String personNo : personNoList) { Map<String, Object> callMap = callMapList.stream().filter(map -> personNo.equals(map.get("personNo"))).findAny().get(); List<CallRecord> callList = (List<CallRecord>) callMap.get("callList"); // 统计通话频率 count += callList.stream().filter(x -> account.equals(x.getRelationshipAccount())).count(); // 获取涉案人 personVoList.add(personList.stream().filter(person -> personNo.equals(person.getPersonNo())).findAny().get()); } // 共同号码是否属于涉案人 String commonPersonName = getCommonPersonName(personList, account); if (frequency != null && frequency > 0) { if (count >= frequency) { vo.setPersons(personVoList); vo.setCommonAccount(account); vo.setFrequency(count); vo.setCommonPersonName(commonPersonName); } return vo; } else { vo.setPersons(personVoList); vo.setCommonAccount(account); vo.setFrequency(count); vo.setCommonPersonName(commonPersonName); return vo; } } else { return vo; } }, executor); futureList.add(future); } voList.addAll(futureList.stream().map(CompletableFuture::join) .distinct().sorted(Comparator.comparing(vo -> vo.getPersons().size())) .collect(Collectors.toList()));

优化后的代码如下：

List<CompletableFuture<CallIntersectionVo>> futureList = intersectionResult.entrySet().stream()
        .map(entry -> CompletableFuture.supplyAsync(() -> {
            String account = entry.getKey();
            List<String> personNoList = entry.getValue().stream().distinct().collect(Collectors.toList());
            CallIntersectionVo vo = new CallIntersectionVo();
            if (personNoList.size() >= 2) {
                List<PersonBasicVo> personVoList = personNoList.stream()
                        .map(personNo -> {
                            Map<String, Object> callMap = callMapList.stream()
                                    .filter(map -> personNo.equals(map.get("personNo")))
                                    .findAny()
                                    .orElseThrow(() -> new NoSuchElementException("Person not found"));
                            List<CallRecord> callList = (List<CallRecord>) callMap.get("callList");
                            int count = (int) callList.stream().filter(x -> account.equals(x.getRelationshipAccount())).count();
                            return personList.stream()
                                    .filter(person -> personNo.equals(person.getPersonNo()))
                                    .findAny()
                                    .orElseThrow(() -> new NoSuchElementException("Person not found"));
                        })
                        .collect(Collectors.toList());
                String commonPersonName = getCommonPersonName(personList, account);

                vo.setPersons(personVoList);
                vo.setCommonAccount(account);
                vo.setFrequency(personVoList.size());
                vo.setCommonPersonName(commonPersonName);

                return vo;
            } else {
                return vo;
            }
        }, executor))
        .collect(Collectors.toList());

List<CallIntersectionVo> voList = futureList.stream()
        .map(CompletableFuture::join)
        .distinct()
        .sorted(Comparator.comparingInt(vo -> vo.getPersons().size()))
        .collect(Collectors.toList());

主要优化：
1. 使用流式编程，替换原来的for循环和entrySet遍历。
2. 使用`stream()`和`collect(Collectors.toList())`方法来收集结果，代替手动添加到列表中。
3. 使用`orElseThrow`方法来处理可能找不到元素的情况，避免空指针异常。
4. 将lambda表达式内联，使代码更简洁。
5. 使用`Comparator.comparingInt`方法来指定排序规则，避免编译器警告。

优化以下代码 Map<String, Integer> resultMap = new HashMap<>(); List<StubDiffTimeDiscountBO> list = new ArrayList<>(); for (StubDiffTimeDiscountBO stubDiscountBO : boList) { String tmp = stubDiscountBO.getStupGroupId(); int count = resultMap.get(tmp) != null ? resultMap.get(tmp) : 0; count = count + 1; resultMap.put(tmp, count); } resultMap.keySet().stream().filter(getKey -> resultMap.get(getKey) != 1).forEach(getKey -> { StubDiffTimeDiscountBO bo = new StubDiffTimeDiscountBO(); bo.setStupGroupId(getKey); list.add(bo); }); List<String> repeatIdList = list.stream().map(StubDiffTimeDiscountBO::getStupGroupId).collect(Collectors.toList());

优化后的代码如下：

Map<String, Integer> resultMap = new HashMap<>();
List<String> repeatIdList = new ArrayList<>();

for (StubDiffTimeDiscountBO stubDiscountBO : boList) {
    String tmp = stubDiscountBO.getStupGroupId();
    int count = resultMap.getOrDefault(tmp, 0);
    count++;
    resultMap.put(tmp, count);
    if (count == 2) {
        repeatIdList.add(tmp);
    }
}

List<StubDiffTimeDiscountBO> list = repeatIdList.stream().map(id -> {
    StubDiffTimeDiscountBO bo = new StubDiffTimeDiscountBO();
    bo.setStupGroupId(id);
    return bo;
}).collect(Collectors.toList());

优化的细节如下：

1. 用`Map.getOrDefault`方法替代`Map.get`方法判断null的情况；
2. 用if语句判断重复次数，避免多次遍历结果集；
3. 用`stream`流替代原来的`keySet`方法，避免多次遍历结果集；
4. 直接用`map`方法映射`StubDiffTimeDiscountBO`对象，避免手动添加到`list`中。