Java:展平列表或对象的列表，保留类

import java.util.ArrayList;
import java.util.List;

public class FlattenList {
    public static List<Object> flatten(List<Object> inputList) {
        List<Object> flattenedList = new ArrayList<>();
        for (Object item : inputList) {
            if (item instanceof List) {
                flattenedList.addAll(flatten((List<Object>) item));
            } else {
                flattenedList.add(item);
            }
        }
        return flattenedList;
    }

    public static void main(String[] args) {
        List<Object> nestedList = new ArrayList<>();
        nestedList.add(1);
        nestedList.add(2);
        nestedList.add(List.of(3, 4));
        nestedList.add(5);
        nestedList.add(List.of(6, List.of(7, 8)));

        List<Object> flattenedList = flatten(nestedList);
        System.out.println(flattenedList);
    }
}

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class FlattenList {
    public static List<Object> flatten(List<Object> inputList) {
        return inputList.stream()
                .flatMap(item -> item instanceof List ? flatten((List<Object>) item).stream() : Stream.of(item))
                .collect(Collectors.toList());
    }

    public static void main(String[] args) {
        List<Object> nestedList = new ArrayList<>();
        nestedList.add(1);
        nestedList.add(2);
        nestedList.add(List.of(3, 4));
        nestedList.add(5);
        nestedList.add(List.of(6, List.of(7, 8)));

        List<Object> flattenedList = flatten(nestedList);
        System.out.println(flattenedList);
    }
}