JDK8-Stream（Map）

业务需求

代码实现

public static void mapDemo(){

        Map<String, List<ApproverDTO>> approvers = new HashMap<>();
        List<String> ancestorGeoUnitIds = new ArrayList<>();
        //init
        List<ApproverDTO> s1 = new ArrayList();
        Collections.addAll(s1,ApproverDTO.builder().geographicUnitId("1").build(),ApproverDTO.builder().geographicUnitId("2").build(),ApproverDTO.builder().geographicUnitId("3").build());
        approvers.put("CFO1",s1);

        List<ApproverDTO> s2 = new ArrayList();
        Collections.addAll(s2,ApproverDTO.builder().geographicUnitId("1").build(),ApproverDTO.builder().geographicUnitId("2").build(),ApproverDTO.builder().geographicUnitId("3").build());
        approvers.put("CFO2",s2);

        Collections.addAll(ancestorGeoUnitIds,"2","3");



        Map<String, List<ApproverDTO>> listMap = approvers.entrySet().stream().map(entry -> {
            System.out.println("key-" + entry.getKey() + ":value-" + entry.getValue());
            List<ApproverDTO> value = entry.getValue();

            List<ApproverDTO> result =null;
            for (String ancestorGeoUnitId:ancestorGeoUnitIds) {
                result = value.stream().filter(approverDTO -> ancestorGeoUnitId.equalsIgnoreCase(approverDTO.getGeographicUnitId())).collect(Collectors.toList());
                if(!CollectionUtils.isEmpty(result)){
                    break;
                }
            }

            entry.setValue(result);
            return entry;
        }).collect(Collectors.toMap(entry1 -> entry1.getKey(), entry1 -> entry1.getValue()));


        System.out.println("------");
    }