使用lamba中stream 进行分组统计

@Test
public void test8() {
    List<String> items =
            Arrays.asList("1", "2", "3",
                    "4", "1", "3", "3");
    Map<String, Long> result =
            items.stream().collect(
                    Collectors.groupingBy(
                            Function.identity(), Collectors.counting()
                    )
            );
    System.out.println(result);
}