java - 当 hashmap 值是多个属性 java 8 的对象列表时如何排序

Question

假设我有:

  Map<String, List<MyState>> map = new HashMap<>();
  map.computeIfAbsent(key, file -> new ArrayList<>()).add(myState);


  map.put("aa",list1..)
  map.put("bb",list2..)
  map.put("cc",list3..)

public class MyState {
    private String state;
    private String date;
}

我想对 map 值进行排序 List<MyState>通过 MyState::date然后通过 MyState::state

Answer 1

您可以这样做:

Comparator<MyState> comparator = Comparator.comparing(MyState::getDate)
                                        .thenComparing(MyState::getState);
map.values()
   .forEach(l -> l.sort(comparator));