摘要：1.登陆官网：https://www.oracle.com 2.显示出下载页面 3.找到Java 4.点击Java（JDK） for Developers 5.选择JDK1.8
阅读全文
posted @ 2020-03-04 07:21
随笔分类 - Java
摘要：Map<String,Bean> map = list.stream().collect(Collectors.toMap(bean -> bean.getItemA(),bean->bean));
阅读全文
posted @ 2020-02-29 14:35
摘要：Map<String,String> itemMap = itemList.stream.collect(Collectors.toMap(Bean::getItemA,Bean::getItemB));
阅读全文
posted @ 2020-02-29 11:10
摘要：public static <T> List<List<T>> split(List<T> sourceList, int count) { List<List<T>> resultList = new ArrayList<>(); int size = sourceList.size(); if
阅读全文
posted @ 2020-02-29 10:42
摘要：List<String> itemList = itemMap.entrySet().stream() .collect(Collectors.groupingBy(e -> e.getKey().substring(11))) .keySet() .stream() .map(key -> key
阅读全文
posted @ 2020-02-29 10:31
摘要：List<String> itemList = list.stream().collect(Collectors.groupingBy(Bean::getItem)).keySet().stream().map(key -> key).collect(Collectors.toList());
阅读全文
posted @ 2020-02-29 09:56
摘要：1.一个一个项目的分组合计 list.stream().collect( Collectors..groupingBy( Bean::getItemA ,Collectors..groupingBy( Bean::getItemB, Collectors..reducing( new Bean(),
阅读全文
posted @ 2020-02-29 09:13
摘要：1.item1升序，item2升序，item3（存在NULL项目，NULL项目排在后面）升序 Collections.sort(list, Comparator.comparing(Bean::getItem1) .thenComparing(Bean::getItem2) .thenCompari
阅读全文
posted @ 2020-02-26 22:36
摘要：Map<String, List<Bean>> orderMap = list.stream().collect(Collectors.groupingBy(Bean::getItem1, LinkedHashMap::new, Collectors.toCollection(ArrayList::
阅读全文
posted @ 2020-02-26 22:32
摘要：1.新创建一个对象 long startTimeA = System.currentTimeMillis(); StringBuilder sb = null; for (int i = 1; i <= 10000000; i++) { sb = new StringBuilder(); sb.ap
阅读全文
posted @ 2020-02-26 22:30
摘要：Map<String, List<Model>> modelMap = modelList .stream() .collect(Collectors .toMap(model -> model.getDate(), model -> new ArrayList<Model>(Arrays.asLi
阅读全文
posted @ 2020-02-20 09:09