JAVA8使用

https://juejin.cn/post/7033005110716448776

1. list中的对象某个属性存在重复时将重复的对象去重
   //根据skuAttrValueName值去重

    List<SkuValue> uniqueSkuValues = skuValues.stream().collect(
            Collectors.collectingAndThen(Collectors.toCollection(
                    () -> new TreeSet<>(Comparator.comparing(o -> o.getSkuAttrValueName()))), ArrayList::new)
    );

2. java8获得对象集合中 某个属性的集合

   List patientIdList = relationDOList.stream().map(RelationDO::getPatientId).collect(Collectors.toList());

3. 收集成实体本身map ```java public Map getIdAccountMap(List accounts) { return accounts.stream().collect(Collectors.toMap(Account::getId, account -> account)); }

public Map getIdNameMap(List accounts) { return accounts.stream().collect(Collectors.toMap(Account::getId, Account::getUsername)); }

4.  bigdecimal求和计算
```java
BigDecimal openDyeAmount = CollUtil.def(sub == null ? null : sub.getDetails()).stream().filter(e -> e.getOpenDyeAmount() != null)
        .map(DyeSubOrderDetailDTO::getOpenDyeAmount).reduce(BigDecimal.ZERO, BigDecimal::add);

1. 根据字段属性去重

   List<DyeSubOrderDetailDTO> basFinishedGoodsColorList = CollUtil.def(sub == null ? CollUtil.emptyList() : sub.getDetails()).stream()
       .collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(DyeSubOrderDetailDTO::getBasFinishedGoodsColorId))), ArrayList::new));

2. 分组

   warehouseAllocationReceiveDetailDTOList.stream().collect(Collectors.groupingBy(WarehouseAllocationReceiveDetailDTO::getDyeOrderId));

6.排序

List<StudentInfo> studentsSortName = studentList.stream().sorted(Comparator.comparing(StudentInfo::getAge)).collect(Collectors.toList());