Java8 Streams:如何在要由collect/groupingBy函数访问的映射之前保留值

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        List<String> fruits = Arrays.asList("apple", "banana", "cherry", "date", "elderberry");

        Map<Integer, List<String>> lengthGroups = fruits.stream()
                .peek(System.out::println) // 在分组之前打印每个元素
                .collect(Collectors.groupingBy(String::length));

        System.out.println(lengthGroups);
    }
}

apple
banana
cherry
date
elderberry
{5=[apple], 6=[banana, cherry], 4=[date], 10=[elderberry]}