java jdk8 grammar record

1. The desired result was filtered off to take a first

Optional stock = vo.stream().filter(v->“100”.equals(page.getProductCode())).findFirst();
if (stock.isPresent()) {
StockWarQueryVo stock4 = stock.get();
stockVo.setProductName(stock4.getProductName());
}

2. Filter out the desired result set

List vehicleInfos = list.stream().filter(a ->100==a.getSysOrgId()).collect(Collectors.toList());

3. Remove ids

List productCodes = vo.stream().map(StockWarQueryVo::getProductCode).collect(Collectors.toList());

4.list id to key into the map

Map<Long, User> maps = userList.stream().collect(Collectors.toMap(User::getId,Function.identity()));

The attribute grouping

Map<String, List> detailsMap01 = list.stream()
.collect(Collectors.groupingBy(User::getId));

6. Sort

(1) ascending

Collections.sort(result, Comparator.comparing(ProVendorCategoryTreeVo::getClassifySort));

(2) Descending

Collections.sort(result, Comparator.comparing(ProVendorCategoryTreeVo::getClassifySort).reversed());

(3) first descending and then ascending

Collections.sort(result, Comparator.comparing(ProVendorCategoryTreeVo::getClassifySort)).thenComparing(ProVendorCategoryTreeVo::getId).reversed();