java对数组进行分组_java8 stream对数组按条件进行分组

//对数据做分组(分组条件：组织+对象)

List> list2 = new ArrayList<>();

Map map1 = new HashMap<>();

map1.put("organization", "北京");

map1.put("object", "故宫");

map1.put("score", "90");

list2.add(map1);

Map map2 = new HashMap<>();

map2.put("organization", "北京");

map2.put("object", "故宫");

map2.put("personQty", "8万");

list2.add(map2);

Map map3 = new HashMap<>();

map3.put("organization", "南京");

map3.put("object", "博物院");

map3.put("score", "80");

list2.add(map3);

Map map4 = new HashMap<>();

map4.put("organization", "南京");

map4.put("object", "博物院");

map4.put("personQty", "3万");

list2.add(map4);

List> groupList = list2.stream().collect(Collectors.groupingBy(d -> d.get("organization")

+ "||" + d.get("object"))).entrySet()

.stream().map(d -> {

Map map = new HashMap<>();

map.put("entrustList", d.getValue());

map.put("groupKey", d.getKey());

return map;

}).collect(Collectors.toList());