Gson FromJson 返回 null。我错过了什么？

Question

我尝试使用 gson fromJson 但每次都会收到此打印 => Country(countries=null) 。我错过了什么？

//代码

data class Countries(val countries: Map<String, List<String>>)

val jsonString = """
    {
      "Afghanistan": [
        "Herat",
        "Kabul",
        "Kandahar",
        "Molah",
        "Rana",
        "Shar",
        "Sharif",
        "Wazir Akbar Khan"
      ],
      "Albania": [
        "Elbasan",
        "Petran",
        "Pogradec",
        "Shkoder",
        "Tirana",
        "Ura Vajgurore"
      ]
    }
""".trimIndent()

        val countries = Gson().fromJson(jsonString, Countries::class.java)
        println(countries)

Answer 1

找不到

countries

键。请尝试这个：

val jsonString = """
{
  "countries": {
    "Afghanistan": [
      "Herat",
      "Kabul",
      "Kandahar",
      "Molah",
      "Rana",
      "Shar",
      "Sharif",
      "Wazir Akbar Khan"
    ],
    "Albania": [
      "Elbasan",
      "Petran",
      "Pogradec",
      "Shkoder",
      "Tirana",
      "Ura Vajgurore"
    ]
  }
}
""".trimIndent()