【求助】Java8 对List> 进行分组统计

[神秘csdner]

比方：
Map<String, Object> map = new HashMap<String, Object>();
map.put("name", "a");
map.put("price",500);

Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("name", "a");
map2.put("price",1500);

Map<String, Object> map3 = new HashMap<String, Object>();
map3.put("name", "b");
map3.put("price",300);

List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
list.add(map);
list.add(map2);
list.add(map3);

这样的List，我如何用Java中lambda表达式快速的去分组，实现List中从3个元素变为a，2000和b，300的2个元素呢？

[baidu_25526097]

Map<String, Object> map = new HashMap<String, Object>();
map.put("name", "a");
map.put("price",500);

Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("name", "a");
map2.put("price",1500);

Map<String, Object> map3 = new HashMap<String, Object>();
map3.put("name", "b");
map3.put("price",300);

List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
list.add(map);
list.add(map2);
list.add(map3);



List<Map<String,Object>> result =new ArrayList<>();

Map<String, List<Map<String, Object>>> glist = list.stream().collect(Collectors.groupingBy(e -> e.get("name").toString()));

glist.forEach((k,slist)->{
Map<String,Object> nmap=new HashMap<>();
IntSummaryStatistics sumcc = slist.stream().collect(Collectors.summarizingInt(e->Integer.valueOf(e.get("price").toString())));
nmap.put("name", slist.get(0).get("name"));
nmap.put("price", sumcc.getSum());//求和
result.add(nmap);


});
System.out.println("--------testMerge-------------");
result.forEach(x->{
System.out.println(x);
});

[qq_32639373]

Map<String, List<Map<String, Object>>> glist = list.stream().collect(Collectors.groupingBy(e -> e.get("name").toString())); 为什呢这行代码在idea里报错

[suke_zzss]

引用 2 楼 qq_32639373 的回复:

Map<String, List<Map<String, Object>>> glist = list.stream().collect(Collectors.groupingBy(e -> e.get("name").toString()));

为什呢这行代码在idea里报错

你用的是jdk1.8以上吗