四时宝库

public static void main(String[] args) {
		Map<String, String> map = new HashMap<>();
		map.put("b", "b");
		map.put("d", "d");
		map.put("c", "c");

		// 按key排序
		Set<String> set = map.keySet();
		Object [] arr =  set.toArray();
		Arrays.sort(arr);
		for (Object str : arr) {
			System.out.println(str);
		}

		// 按value排序
		List<Map.Entry<String, String>> entries = new ArrayList<>(map.entrySet());
		Collections.sort(entries, Comparator.comparing(Map.Entry::getValue));
		for (Map.Entry<String, String> m : entries) {
			System.out.println(m.getValue());
		}
	}