Java 8 streams维护group by操作返回的特定映射键顺序

import java.util.*;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David", "Eve", "Frank");

        // 使用group by操作将names分组为按名称长度分组的Map
        Map<Integer, List<String>> groupedNames = names.stream()
                .collect(Collectors.groupingBy(String::length, TreeMap::new, Collectors.toList()));

        // 打印分组结果
        for (Map.Entry<Integer, List<String>> entry : groupedNames.entrySet()) {
            System.out.println("Key: " + entry.getKey() + ", Values: " + entry.getValue());
        }
    }
}

Key: 3, Values: [Bob]
Key: 4, Values: [Eve]
Key: 5, Values: [Alice, David, Frank]
Key: 7, Values: [Charlie]