在Java中将映射数据分组到嵌套的HashMap中

import java.util.HashMap;
import java.util.Map;

public class GroupMappingExample {
    public static void main(String[] args) {
        // 创建主HashMap对象
        HashMap<String, HashMap<String, Object>> groupedData = new HashMap<>();

        // 模拟映射数据
        Map<String, Object> data1 = new HashMap<>();
        data1.put("name", "John");
        data1.put("age", 25);

        Map<String, Object> data2 = new HashMap<>();
        data2.put("name", "Jane");
        data2.put("age", 30);

        Map<String, Object> data3 = new HashMap<>();
        data3.put("name", "Mike");
        data3.put("age", 28);

        // 将映射数据分组到嵌套的HashMap中
        addToGroup(data1, "group1", groupedData);
        addToGroup(data2, "group2", groupedData);
        addToGroup(data3, "group1", groupedData);

        // 打印分组结果
        for (Map.Entry<String, HashMap<String, Object>> entry : groupedData.entrySet()) {
            String group = entry.getKey();
            HashMap<String, Object> groupData = entry.getValue();

            System.out.println("Group: " + group);
            for (Map.Entry<String, Object> dataEntry : groupData.entrySet()) {
                String key = dataEntry.getKey();
                Object value = dataEntry.getValue();
                System.out.println(key + ": " + value);
            }
            System.out.println();
        }
    }

    private static void addToGroup(Map<String, Object> data, String group, HashMap<String, HashMap<String, Object>> groupedData) {
        // 获取分组对应的嵌套HashMap对象
        HashMap<String, Object> groupData = groupedData.get(group);

        // 如果分组对应的嵌套HashMap对象为null，创建新的HashMap对象并放入主HashMap中
        if (groupData == null) {
            groupData = new HashMap<>();
            groupedData.put(group, groupData);
        }

        // 将数据项存放到嵌套HashMap中
        groupData.putAll(data);
    }
}

Group: group1
name: John
age: 25

Group: group2
name: Jane
age: 30