Java 通过value值排序Map方法代码

1、Java 8 使用AbacusUtil实现

AbacusUtil:https://github.com/landawn/AbacusUtil

Map<String, Integer> map = N.asMap("a", 2, "b", 3, "c", 1, "d", 2);
Map<String, Integer> sortedMap = Stream.of(map.entrySet()).sorted(Map.Entry.comparingByValue()).toMap(e -> e.getKey(), e -> e.getValue(),
    LinkedHashMap::new);
N.println(sortedMap);
// output: {c=1, a=2, d=2, b=3}

2、使用for循环实现

public >Test  {
    public static void main(String[] args)  {
        HashMap<String, Long> hashMap = new HashMap<>();
        hashMap.put("Cat", (long) 4);
        hashMap.put("Human", (long) 2);
        hashMap.put("Dog", (long) 4);
        hashMap.put("Fish", (long) 0);
        hashMap.put("Tree", (long) 1);
        hashMap.put("Three-legged-human", (long) 3);
        hashMap.put("Monkey", (long) 2);
        System.out.println(hashMap);  //{Human=2, Cat=4, Three-legged-human=3, Monkey=2, Fish=0, Tree=1, Dog=4}
        System.out.println(sortHashMap(hashMap));  //{Cat=4, Dog=4, Three-legged-human=3, Human=2, Monkey=2, Tree=1, Fish=0}
    }
    public LinkedHashMap<String, Long> sortHashMap(HashMap<String, Long> unsortedMap)  {
        LinkedHashMap<String, Long> result = new LinkedHashMap<>();
        //add String keys to an array: the array would get sorted, based on those keys' values
        ArrayList<String> sortedKeys = new ArrayList<>();
        for (String key: unsortedMap.keySet())  {
            sortedKeys.add(key);
        }
        //sort the ArrayList<String> of keys    
        for (int i=0; i<unsortedMap.size(); i++)  {
            for (int j=1; j<sortedKeys.size(); j++)  {
                if (unsortedMap.get(sortedKeys.get(j)) > unsortedMap.get(sortedKeys.get(j-1))) {
                    String temp = sortedKeys.get(j);
                    sortedKeys.set(j, sortedKeys.get(j-1));
                    sortedKeys.set(j-1, temp);
                }
            }
        }
        // construct the result Map
        for (String key: sortedKeys)  {
            result.put(key, unsortedMap.get(key));
        }
        return result;
    }
}

3、使用stream()实现

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

4、使用ArrayList排序实现

public >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;
    }
}