stream语法使用

2023-06-28

排序

1 2	seriesMap.keySet().stream(). sorted(Collections.reverseOrder()).collect(Collectors.toList())

分组

1	list.stream().collect(Collectors.groupingBy(DutyTurns::getOrderno))

根据id

1	Map<String,DutyClasses>classMap=classList.stream().collect(Collectors.toMap(DutyClasses::getUuid,DutyClasses->DutyClasses));

取集合一条数据

1	DutyLogdutyLog=dutyLogMapper.selectDutyLogList(null).stream().reduce((first,second)->second).get();

集合去重

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inetAddresses.stream().map(InetAddress::getHostAddress).distinct().map(String::toLowerCase).collect(Collectors.toList());

kpiHandovers.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(()->newTreeSet<>(Comparator.comparing(KpiHandover::getDutyLogUuid))),ArrayList::new))

取平局值

1	list.stream().mapToDouble(TagValue::getValue).average().getAsDouble()

前5条数据

1	noticeService.selectNoticeList(notice).stream().limit(5l).collect(Collectors.toList());

筛选

1	historicProcessInstances=historicProcessInstances.stream().filter(historic->historic.getProcessDefinitionName().indexOf(flowTaskVo.getProcDefName())<0).collect(Collectors.toList());

集合

1	List<DictEntity> dictEntityList = dictService.findByType(6);

取出属性为集合

1	List<String> stateNameList = dictEntityList.stream().map(DictEntity::getName).collect(Collectors.toList());

取出属性为数组

1	Long[] ids = dictEntityList.stream().map(DictEntity::getId).toArray(Long[]::new);

集合去重

1	dictEntityList.stream().distinct().collect(Collectors.toList());

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