public static void main(String[] args) {
        // 根据key升序排序
        Map<String, Integer> mapAsc = new TreeMap<>();

        mapAsc.put("b", 5);
        mapAsc.put("a", 10);
        mapAsc.put("d", 11);
        mapAsc.put("c", 13);
        System.out.println("按key升序排序");
        System.out.println(mapAsc);
        System.out.println();

        // 根据key降序排序
        Map<String, Integer> mapDesc = new TreeMap<>(Comparator.reverseOrder());
        mapDesc.putAll(mapAsc);
        System.out.println("按key降序排序");
        System.out.println(mapDesc);
        System.out.println();

        // 根据value升序排序
        List<Map.Entry<String, Integer>> listAsc = new ArrayList<>(mapAsc.entrySet());
        listAsc.sort(Comparator.comparingInt(Map.Entry::getValue));
        System.out.println("按value升序排序");
        listAsc.forEach(e -> System.out.println(e.getKey() + ": " + e.getValue()));
        System.out.println();

        // 根据value降序排序
        List<Map.Entry<String, Integer>> listDesc = new ArrayList<>(mapAsc.entrySet());
        listDesc.sort((e1, e2) -> e2.getValue() - e1.getValue());
        System.out.println("按value降序排序");
        listDesc.forEach(e -> System.out.println(e.getKey() + ": " + e.getValue()));
    }

程序运行结果

按key升序排序
{a=10, b=5, c=13, d=11}

按key降序排序
{d=11, c=13, b=5, a=10}

按value升序排序
b: 5
a: 10
d: 11
c: 13

按value降序排序
c: 13
d: 11
a: 10
b: 5