How to get values from Map of Map in JAVA [重复]

Question

我正在尝试从 Map 中的 Map 中获取所有值

我正在使用的数据类型： Map> userDetails = new HashMap>();

样本数据：

{
  "user1": {
    "admin": {
      "department_name": "Marketing",
      "first_name": "Peter"
    },
    "editor": {
      "department_name": "Sales",
      "first_name": "John"
    }
  },
  "user2": {
    "admin": {
      "department_name": "Advertisement",
      "first_name": "Emmanuel"
    },
    "editor": {
      "department_name": "HR",
      "first_name": "Anna"
    }
  }
}

我希望将所有值存储在一个列表中>

[
  {
    "department_name": "Marketing",
    "first_name": "Peter"
  },
  {
    "department_name": "Sales",
    "first_name": "John"
  },
  {
    "department_name": "Advertisement",
    "first_name": "Emmanuel"
  },
  {
    "department_name": "HR",
    "first_name": "Anna"
  }
]