Java 访问 JSON 字符串中的数据

Question

我在访问 JSON 字符串中的数据时遇到问题。我做错了什么？

工作:

JSONObject obj = new JSONObject("JSON-STRING");
JSONArray arr = obj.getJSONArray("weather");
System.out.println(arr.getJSONObject(0).get("description"); >> clear sky

不工作:

JSONObject obj = new JSONObject("JSON-STRING");
JSONArray arr = obj.getJSONArray("main");
System.out.println(arr.getJSONObject(0).get("temp"); >> 285.15

异常(exception):

org.json.JSONException: JSONObject["main"] is not a JSONArray.
    at org.json.JSONObject.getJSONArray(JSONObject.java:622)
    at main.SmartHomeBot.onUpdateReceived(SmartHomeBot.java:47)
    at org.telegram.telegrambots.updatesreceivers.DefaultBotSession$HandlerThread.run(DefaultBotSession.java:274)

JSON 字符串:

{
    "coord": {
        "lon": 6.55,
        "lat": 51.27
    },
    "weather": [{
            "id": 800,
            "main": "Clear",
            "description": "clear sky",
            "icon": "01d"
        }
    ],
    "base": "stations",
    "main": {
        "temp": 285.15,
        "pressure": 1034,
        "humidity": 30,
        "temp_min": 285.15,
        "temp_max": 285.15
    },
    "visibility": 10000,
    "wind": {
        "speed": 2.6
    },
    "clouds": {
        "all": 0
    },
    "dt": 1492705200,
    "sys": {
        "type": 1,
        "id": 4909,
        "message": 0.2825,
        "country": "DE",
        "sunrise": 1492662386,
        "sunset": 1492713582
    },
    "id": 2808559,
    "name": "Willich",
    "cod": 200
}

Answer 1

您会收到错误消息，因为 weather 是多个 weather 的数组，而 main 是单个对象。

两者的区别如下图所示:

 "weather": [{
        "id": 800,
        "main": "Clear",
        "description": "clear sky",
        "icon": "01d"
    }
],

和

"main": {
    "temp": 285.15,
    "pressure": 1034,
    "humidity": 30,
    "temp_min": 285.15,
    "temp_max": 285.15
},

所以在 JSON "weather": [{....}, {....}, {....}] [] 中显示weather 就是数组。