将Map<String、ArrayList<String>>转换为嵌套JSON

import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MapToJsonExample {
    public static void main(String[] args) {
        // 创建一个 Map<String, ArrayList<String>>
        Map<String, ArrayList<String>> map = new HashMap<>();
        ArrayList<String> list1 = new ArrayList<>();
        list1.add("item1");
        list1.add("item2");
        ArrayList<String> list2 = new ArrayList<>();
        list2.add("item3");
        list2.add("item4");

        map.put("key1", list1);
        map.put("key2", list2);

        // 使用 Jackson 将 Map 转换为 JSON 字符串
        ObjectMapper objectMapper = new ObjectMapper();
        try {
            String jsonString = objectMapper.writeValueAsString(map);
            System.out.println(jsonString);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}