java中如何将Map按Value排序

工具类

public class MapUtil {
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map) {
        List<Entry<K, V>> list = new ArrayList<>(map.entrySet());
        list.sort(Entry.comparingByValue());

        Map<K, V> result = new LinkedHashMap<>();
        for (Entry<K, V> entry : list) {
            result.put(entry.getKey(), entry.getValue());
        }

        return result;
    }
}

java 8

升序

Stream<Map.Entry<K,V>> sorted =
    map.entrySet().stream()
       .sorted(Map.Entry.comparingByValue());

降序

Stream<Map.Entry<K,V>> sorted =
    map.entrySet().stream()
       .sorted(Collections.reverseOrder(Map.Entry.comparingByValue()));

指定比较器

Stream<Map.Entry<K,V>> sorted =
    map.entrySet().stream()
       .sorted(Map.Entry.comparingByValue(comparator));

得到排序后的前10个

Map<K,V> topTen =
    map.entrySet().stream()
       .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
       .limit(10)
       .collect(Collectors.toMap(
          Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));