Java 8中stream相關用法
jdk1.8新加了lambda表示式，可以幫助開發者更好的，更高效的實現一些通常複雜的程式碼實現
1.list轉換map
Map<Integer, String> mappedMovies = ghslist.stream().collect( Collectors.toMap(SaleStaticsGhsResp::getShop_saleman_id, (p) -> p.getName()));
2.從實體中取出id集合,去重
List<Integer> list = page.stream().filter(m->m.getId()>0).map(k -> k.getId()).distinct().collect(Collectors.toList());
3.遍歷一個list，和另一個list對比，取出id相同的每個實體
SaleMan sale = saleList.stream().filter(e -> e.getId().intValue() == olm.getSm_saleman_id()).findFirst().orElse(null);
4.排序(先按第一個欄位排序，如果排序欄位相等，在按第二個欄位排序)
Comparator<SpreadActivityResp> comparator0 =(b, a) -> a.getCreate_time().compareTo(b.getCreate_time());
resultList.sort(comparator0);
Comparator<SpreadActivityResp> comparator = comparator0.thenComparing((a,b) -> b.getCreate_time().compareTo(a.getCreate_time()));
for (CartGoodsInfo info : shop.getGoodsInfoList()) {
cartList.add(info.getCartInfo());
info.getPriceInfoList().sort((a, b) -> {
return a.getMinCount().compareTo(b.getMinCount());
});
priceList.addAll(info.getPriceInfoList());
}
list_order_goods.sort((a,b)->{return Integer.valueOf(a.getId()).compareTo(b.getId());});
5.根據某個id獲取list中和這個id相同的實體
List<Price> pricelist = pricesList.stream().filter(k -> {return skuListId.contains(k.getSku_id());}).collect(Collectors.toList());
List<SearchOrderGoodsResp> unzpList = list_order_goods.stream().filter(m->m.getIs_giveaway() == 0).distinct().collect(Collectors.toList());
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作者：yinghuananhai
來源：CSDN
原文：https://blog.csdn.net/YingHuaNanHai/article/details/81273059
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