Java 通过TreeMap对Map进行转化按照Kep排序

  public static void main(String[] args) {
        Map<Integer,String> map = new HashMap<>();
        map.put(1,"1");
        map.put(32,"2");
        map.put(21,"3");
        map.put(42,"4");
        System.out.println(map);
        TreeMap<Integer, String> treeMap = new TreeMap<>(new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                // o1 比 o2 大，返回正数 o1排在后面
                return o1.compareTo(o2);
            }
        });
        treeMap.putAll(map);
        System.out.println(treeMap);
    }