List<UserInfo> list = systemUserList.stream().map(m -> BeanUtil.toBean(m, UserInfo.class)).collect(Collectors.toList());这是什么意思
时间: 2024-05-21 18:18:47 浏览: 108
这段代码使用了Java 8的Stream API,对一个名为systemUserList的列表进行了操作,将每个元素(类型为m)通过BeanUtil工具类的转换,转换成了UserInfo对象,并将转换后的结果收集到一个新的列表中返回。其中:
- `map()`方法将列表中的每个元素(即systemUserList中的每个对象)映射成一个UserInfo对象。
- `BeanUtil.toBean(m, UserInfo.class)`方法将每个元素转换成UserInfo对象。
- `collect(Collectors.toList())`方法将所有转换后的UserInfo对象收集到一个新的列表中,并返回该列表。
换句话说,这段代码的作用是将一个列表中的每个元素都转换成另外一个对象,并将转换后的结果收集到一个新的列表中返回。
相关问题
UserInfo userInfo=userProvider.get(); OrganizeEntity organize = organizeService.getById(userInfo.getDepartmentId()); TreeMap<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMap = tzglInvestmentPlanService.selectProjectDetial(params,organize); for (String key : investmentPlanProjectMap.keySet()) { List<TzglInvestmentPlanProjectModel> projectList = investmentPlanProjectMap.get(key); for (TzglInvestmentPlanProjectModel investmentPlanProject: projectList) { investmentPlanProject.setInvestmentSubjectName(generaterSwapUtil.comSelectValues(investmentPlanProject.getInvestmentSubject())); } } //按照年份分组后,降序排序 TreeMap<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMapDescending = new TreeMap<>(Comparator.reverseOrder()); investmentPlanProjectMapDescending.putAll(investmentPlanProjectMap); return ActionResult.success(investmentPlanProjectMapDescending);优化此代码
可以考虑以下优化:
1. 将获取用户信息和部门信息的代码提取出来,避免在每个方法里都重复获取。
```
UserInfo userInfo = userProvider.get();
OrganizeEntity organize = organizeService.getById(userInfo.getDepartmentId());
```
2. 使用 Stream API 和 lambda 表达式来简化代码。
```
TreeMap<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMap = tzglInvestmentPlanService.selectProjectDetial(params,organize);
investmentPlanProjectMap.forEach((key, projectList) -> projectList.forEach(investmentPlanProject -> investmentPlanProject.setInvestmentSubjectName(generaterSwapUtil.comSelectValues(investmentPlanProject.getInvestmentSubject()))));
TreeMap<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMapDescending = new TreeMap<>(Comparator.reverseOrder());
investmentPlanProjectMapDescending.putAll(investmentPlanProjectMap);
return ActionResult.success(investmentPlanProjectMapDescending);
```
3. 不需要先将 `investmentPlanProjectMap` 存放到一个 TreeMap 中,再进行降序排序。可以直接使用 Stream API 进行分组和排序。
```
Map<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMap = tzglInvestmentPlanService.selectProjectDetial(params,organize);
investmentPlanProjectMap.forEach((key, projectList) -> projectList.forEach(investmentPlanProject -> investmentPlanProject.setInvestmentSubjectName(generaterSwapUtil.comSelectValues(investmentPlanProject.getInvestmentSubject()))));
Map<String, List<TzglInvestmentPlanProjectModel>> investmentPlanProjectMapDescending = investmentPlanProjectMap.entrySet().stream()
.sorted(Map.Entry.<String, List<TzglInvestmentPlanProjectModel>>comparingByKey().reversed())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> oldValue, TreeMap::new));
return ActionResult.success(investmentPlanProjectMapDescending);
```
List<String> landsForVillages = feignBasicController.getLandsForVillages(id); List<DevInfo> devByBaseId = feignHdController.getDevByBaseId(userInfo.getId(), classify); List<String> machineIds = devByBaseId.stream().map(DevInfo::getId).collect(Collectors.toList()); Set<String> machineIdList = new HashSet<>(); // json转化为list for (String machineId : machineIds) { List<String> landIdsList = baseMapper.getLandIdsById(machineId); for (String landIdStr : landIdsList) { if(StringUtils.isNotBlank(landIdStr)){ JSONArray arrayStr = JSON.parseArray(landIdStr); for (Object o : arrayStr) { if (landsForVillages.contains(o)) { // 村下面的工作设备 machineIdList.add(machineId); } } } } } 优化一下代码
可以尝试使用 Java 8 的 Stream API 重构代码,如下所示:
```
Set<String> machineIdList = devByBaseId.stream()
.map(DevInfo::getId)
.flatMap(machineId -> baseMapper.getLandIdsById(machineId).stream())
.filter(StringUtils::isNotBlank)
.flatMap(landIdStr -> JSON.parseArray(landIdStr).stream())
.distinct()
.filter(landsForVillages::contains)
.map(machineIdList::add)
.collect(Collectors.toSet());
```
这段代码首先使用 `flatMap` 将 `devByBaseId` 中的每个 `DevInfo` 转换为其对应的 `machineId`,然后对于每个 `machineId`,调用 `baseMapper.getLandIdsById` 获取其对应的 `landIdsList`,并将其转换为一个 `Stream<String>`。接着对于每个 `landIdStr`,使用 `JSON.parseArray` 将其转换为一个 `JSONArray`,然后将其中的每个元素转换为 `String`,并去重。最后,使用 `filter` 过滤出 `landsForVillages` 中包含的元素,并将其对应的 `machineId` 添加到 `machineIdList` 中,最终使用 `collect` 将其转换为一个 `Set<String>`。
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