如何根据每个键值的大小对LinkedHashMap进行排序？

Question

myMap.entrySet().stream()
         .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
         .collect(Collectors.toMap(
                  Map.Entry::getKey,
                  Map.Entry::getValue,
                  (x,y) -> {throw new AssertionError();},
                  LinkedHashMap::new
         ));

List<Map.Entry<String, Integer>> entries =
  new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
Collections.sort(entries, new Comparator<Map.Entry<String, Integer>>() {
  public int compare(Map.Entry<String, Integer> a, Map.Entry<String,Integer> b){
    return a.getValue().size().compareTo(b.getValue().size());
   }
});
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
for (Map.Entry<String, Integer> entry : entries) {
  sortedMap.put(entry.getKey(), entry.getValue());
}

对LinkedHashMap进行排序

Answer 1

你试过的很接近。以下是一个固定的版本：

List<Map.Entry<Integer, Set<Integer>>> entries = new ArrayList<>(
            map.entrySet());
Collections.sort(entries,
        new Comparator<Map.Entry<Integer, Set<Integer>>>() {
            public int compare(Map.Entry<Integer, Set<Integer>> a,
                    Map.Entry<Integer, Set<Integer>> b) {
                return Integer.compare(
                          a.getValue().size(),
                          b.getValue().size());
            }
        });

Map<Integer, Set<Integer>> sortedMap = new LinkedHashMap<>();
for (Map.Entry<Integer, Set<Integer>> entry : entries) {
    sortedMap.put(entry.getKey(), entry.getValue());
}

用…设置

 LinkedHashMap<Integer, Set<Integer>> map = new LinkedHashMap<>();
 map.put(1, new HashSet<>(Arrays.asList(1,2,3)));
 map.put(2, new HashSet<>(Arrays.asList(1,2)));
 map.put(3, new HashSet<>(Arrays.asList(1)));

和跑步

System.out.println(sortedMap);

{3=[1], 2=[1, 2], 1=[1, 2, 3]}