1、List 转Map<Integer,String> Map<Integer,String> roadMap = dtoList.stream().collect(Collectors.toMap(MaintPlanBaseDTO::getId, MaintPlanBaseDTO::getRoadCode)); 2、List 转 Map<Integer,Object> Map<Integer, BdataOrgContactDTO> map = dtoList.stream() .collect(Collectors.toMap(BdataOrgContactDTO::getDataId, s -> s, (s1, s2) -> s2)); 3、List 转 Map<String ,List> Map<String, List<ApprovalRecordDTO>> map = recordList.stream().collect(Collectors.groupingBy(s -> s.getAfId() + "_" + s.getUserId())); 4、List 转 List List<Long> ids = vos.stream().map(HighwayListVO::getId).distinct().collect(Collectors.toList()); 5、String 转 List 例如：String strArr= "1,2,3,4,5,6" -> List listLong [1,2,3,4,5,6]; public static List<Integer> stringToIntegerList(String strArr) { return Arrays.stream(strArr.split(",")) .map(s -> Integer.parseInt(s.trim())) .collect(Collectors.toList()); } 6、flatMap List<String> asia = Arrays.asList("中国", "日本", "新加坡"); List<String> american = Arrays.asList("美国", "加拿大", "巴拿马"); List<List<String>> country = new ArrayList<>(); country.add(asia); country.add(american); List<String> allContry = new ArrayList<>(); for (List<String> team : country) { for (String name : team) { allContry.add(name); } } /**java8之前遍历方式*/ System.out.println(allContry); /**java8遍历方式*/ List<String> flatMapList = country.stream() .flatMap(pList -> pList.stream()) .collect(Collectors.toList()); 8、List 过滤数据 List<ServiceAreaParkSpaceVO> upList = serviceAreaParkSpaceList.stream().filter(s -> s.getDirection().intValue() == 1).collect(Collectors.toList()); 9、根据集合中的某个字段去重： ArrayList<TrafficSituationAnalysisVO> collect = trafficSituationAnalysisList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(TrafficSituationAnalysisVO::getTimeStr))), ArrayList::new)); 10、List 排序 list = list.stream().sorted(Comparator.comparing(StakeRangeNoVo::getLng).reversed()).collect(Collectors.toList()); 11、Bigdecimal 类型累加 BigDecimal totalServiceFee = list.stream().map(ChargingGunStreamVo::getTotalServiceFee).reduce(BigDecimal.ZERO, BigDecimal::add);
Map<Integer,String> roadMap = dtoList.stream().collect(Collectors.toMap(MaintPlanBaseDTO::getId, MaintPlanBaseDTO::getRoadCode));
2、List 转 Map<Integer,Object> Map<Integer, BdataOrgContactDTO> map = dtoList.stream() .collect(Collectors.toMap(BdataOrgContactDTO::getDataId, s -> s, (s1, s2) -> s2)); 3、List 转 Map<String ,List> Map<String, List<ApprovalRecordDTO>> map = recordList.stream().collect(Collectors.groupingBy(s -> s.getAfId() + "_" + s.getUserId())); 4、List 转 List List<Long> ids = vos.stream().map(HighwayListVO::getId).distinct().collect(Collectors.toList()); 5、String 转 List 例如：String strArr= "1,2,3,4,5,6" -> List listLong [1,2,3,4,5,6]; public static List<Integer> stringToIntegerList(String strArr) { return Arrays.stream(strArr.split(",")) .map(s -> Integer.parseInt(s.trim())) .collect(Collectors.toList()); } 6、flatMap List<String> asia = Arrays.asList("中国", "日本", "新加坡"); List<String> american = Arrays.asList("美国", "加拿大", "巴拿马"); List<List<String>> country = new ArrayList<>(); country.add(asia); country.add(american); List<String> allContry = new ArrayList<>(); for (List<String> team : country) { for (String name : team) { allContry.add(name); } } /**java8之前遍历方式*/ System.out.println(allContry); /**java8遍历方式*/ List<String> flatMapList = country.stream() .flatMap(pList -> pList.stream()) .collect(Collectors.toList()); 8、List 过滤数据 List<ServiceAreaParkSpaceVO> upList = serviceAreaParkSpaceList.stream().filter(s -> s.getDirection().intValue() == 1).collect(Collectors.toList()); 9、根据集合中的某个字段去重： ArrayList<TrafficSituationAnalysisVO> collect = trafficSituationAnalysisList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(TrafficSituationAnalysisVO::getTimeStr))), ArrayList::new)); 10、List 排序 list = list.stream().sorted(Comparator.comparing(StakeRangeNoVo::getLng).reversed()).collect(Collectors.toList()); 11、Bigdecimal 类型累加 BigDecimal totalServiceFee = list.stream().map(ChargingGunStreamVo::getTotalServiceFee).reduce(BigDecimal.ZERO, BigDecimal::add);
Map<Integer, BdataOrgContactDTO> map = dtoList.stream() .collect(Collectors.toMap(BdataOrgContactDTO::getDataId, s -> s, (s1, s2) -> s2));
3、List 转 Map<String ,List> Map<String, List<ApprovalRecordDTO>> map = recordList.stream().collect(Collectors.groupingBy(s -> s.getAfId() + "_" + s.getUserId())); 4、List 转 List List<Long> ids = vos.stream().map(HighwayListVO::getId).distinct().collect(Collectors.toList()); 5、String 转 List 例如：String strArr= "1,2,3,4,5,6" -> List listLong [1,2,3,4,5,6]; public static List<Integer> stringToIntegerList(String strArr) { return Arrays.stream(strArr.split(",")) .map(s -> Integer.parseInt(s.trim())) .collect(Collectors.toList()); } 6、flatMap List<String> asia = Arrays.asList("中国", "日本", "新加坡"); List<String> american = Arrays.asList("美国", "加拿大", "巴拿马"); List<List<String>> country = new ArrayList<>(); country.add(asia); country.add(american); List<String> allContry = new ArrayList<>(); for (List<String> team : country) { for (String name : team) { allContry.add(name); } } /**java8之前遍历方式*/ System.out.println(allContry); /**java8遍历方式*/ List<String> flatMapList = country.stream() .flatMap(pList -> pList.stream()) .collect(Collectors.toList()); 8、List 过滤数据 List<ServiceAreaParkSpaceVO> upList = serviceAreaParkSpaceList.stream().filter(s -> s.getDirection().intValue() == 1).collect(Collectors.toList()); 9、根据集合中的某个字段去重： ArrayList<TrafficSituationAnalysisVO> collect = trafficSituationAnalysisList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(TrafficSituationAnalysisVO::getTimeStr))), ArrayList::new)); 10、List 排序 list = list.stream().sorted(Comparator.comparing(StakeRangeNoVo::getLng).reversed()).collect(Collectors.toList()); 11、Bigdecimal 类型累加 BigDecimal totalServiceFee = list.stream().map(ChargingGunStreamVo::getTotalServiceFee).reduce(BigDecimal.ZERO, BigDecimal::add);
Map<String, List<ApprovalRecordDTO>> map = recordList.stream().collect(Collectors.groupingBy(s -> s.getAfId() + "_" + s.getUserId()));
4、List 转 List List<Long> ids = vos.stream().map(HighwayListVO::getId).distinct().collect(Collectors.toList()); 5、String 转 List 例如：String strArr= "1,2,3,4,5,6" -> List listLong [1,2,3,4,5,6]; public static List<Integer> stringToIntegerList(String strArr) { return Arrays.stream(strArr.split(",")) .map(s -> Integer.parseInt(s.trim())) .collect(Collectors.toList()); } 6、flatMap List<String> asia = Arrays.asList("中国", "日本", "新加坡"); List<String> american = Arrays.asList("美国", "加拿大", "巴拿马"); List<List<String>> country = new ArrayList<>(); country.add(asia); country.add(american); List<String> allContry = new ArrayList<>(); for (List<String> team : country) { for (String name : team) { allContry.add(name); } } /**java8之前遍历方式*/ System.out.println(allContry); /**java8遍历方式*/ List<String> flatMapList = country.stream() .flatMap(pList -> pList.stream()) .collect(Collectors.toList()); 8、List 过滤数据 List<ServiceAreaParkSpaceVO> upList = serviceAreaParkSpaceList.stream().filter(s -> s.getDirection().intValue() == 1).collect(Collectors.toList()); 9、根据集合中的某个字段去重： ArrayList<TrafficSituationAnalysisVO> collect = trafficSituationAnalysisList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(TrafficSituationAnalysisVO::getTimeStr))), ArrayList::new)); 10、List 排序 list = list.stream().sorted(Comparator.comparing(StakeRangeNoVo::getLng).reversed()).collect(Collectors.toList()); 11、Bigdecimal 类型累加 BigDecimal totalServiceFee = list.stream().map(ChargingGunStreamVo::getTotalServiceFee).reduce(BigDecimal.ZERO, BigDecimal::add);
List<Long> ids = vos.stream().map(HighwayListVO::getId).distinct().collect(Collectors.toList());
5、String 转 List 例如：String strArr= "1,2,3,4,5,6" -> List listLong [1,2,3,4,5,6];
public static List<Integer> stringToIntegerList(String strArr) { return Arrays.stream(strArr.split(",")) .map(s -> Integer.parseInt(s.trim())) .collect(Collectors.toList()); }
6、flatMap
List<String> asia = Arrays.asList("中国", "日本", "新加坡"); List<String> american = Arrays.asList("美国", "加拿大", "巴拿马"); List<List<String>> country = new ArrayList<>(); country.add(asia); country.add(american); List<String> allContry = new ArrayList<>(); for (List<String> team : country) { for (String name : team) { allContry.add(name); } } /**java8之前遍历方式*/ System.out.println(allContry); /**java8遍历方式*/ List<String> flatMapList = country.stream() .flatMap(pList -> pList.stream()) .collect(Collectors.toList());
8、List 过滤数据
List<ServiceAreaParkSpaceVO> upList = serviceAreaParkSpaceList.stream().filter(s -> s.getDirection().intValue() == 1).collect(Collectors.toList());
9、根据集合中的某个字段去重：
ArrayList<TrafficSituationAnalysisVO> collect = trafficSituationAnalysisList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(TrafficSituationAnalysisVO::getTimeStr))), ArrayList::new));
10、List 排序
list = list.stream().sorted(Comparator.comparing(StakeRangeNoVo::getLng).reversed()).collect(Collectors.toList());
11、Bigdecimal 类型累加
BigDecimal totalServiceFee = list.stream().map(ChargingGunStreamVo::getTotalServiceFee).reduce(BigDecimal.ZERO, BigDecimal::add);
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