分組List并顯示其總數。

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