Java access data in JSON string

Question

I have problems accessing data in a JSON string. What am I doing wrong?

Working:

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

Not working:

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

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)

The JSON-String:

{
    "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
}

{..} represents object, [..] represents array. As you see "main": {...} holds an object not an array, which is why getJSONArray("main") is causing problems. — Pshemo
– Pshemo, Commented Apr 20, 2017 at 17:58
JSONObject obj = new JSONObject(JSON-STRING); JSONObject arr = obj.getJSONObject("main"); System.out.println(arr.get("temp")); fixed it for me. Thanks! — piguy
– piguy, Commented Apr 20, 2017 at 18:04

Peter Mortensen · Accepted Answer · 2017-04-20 21:32:45Z

1

You get the error because weather is the array of the multiple weather and main is the single object.

Difference between both is shown below:

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

and

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

So in the JSON "weather" : [{....}, {....}, {....}] [] show that weather is the array.

edited Apr 20, 2017 at 21:32

Peter Mortensen

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answered Apr 20, 2017 at 18:15

Anshul Sharma

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Comments

Anil Agrawal · Accepted Answer · 2017-04-20 18:22:57Z

0

In your parent json value for key "weather" represents a JSONArray but value for key "main" represents a JSONObject not JSONArray.

To fetch the data from JsonObject you should do like below

JSONObject mainObj = obj.getJSONObject("main");
System.out.println(mainObj.get("temp"));

answered Apr 20, 2017 at 18:22

Anil Agrawal

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Peter Mortensen · Accepted Answer · 2017-04-20 21:34:21Z

0

String jsonobj = "{\n    \"coord\": {\n        \"lon\": 6.55,\n        \"lat\": 51.27\n    },\n    \"weather\": [{\n            \"id\": 800,\n            \"main\": \"Clear\",\n            \"description\": \"clear sky\",\n            \"icon\": \"01d\"\n        }\n    ],\n    \"base\": \"stations\",\n    \"main\": {\n        \"temp\": 285.15,\n        \"pressure\": 1034,\n        \"humidity\": 30,\n        \"temp_min\": 285.15,\n        \"temp_max\": 285.15\n    },\n    \"visibility\": 10000,\n    \"wind\": {\n        \"speed\": 2.6\n    },\n    \"clouds\": {\n        \"all\": 0\n    },\n    \"dt\": 1492705200,\n    \"sys\": {\n        \"type\": 1,\n        \"id\": 4909,\n        \"message\": 0.2825,\n        \"country\": \"DE\",\n        \"sunrise\": 1492662386,\n        \"sunset\": 1492713582\n    },\n    \"id\": 2808559,\n    \"name\": \"Willich\",\n    \"cod\": 200\n}";
JSONObject obj = new JSONObject(jsonobj);
JSONObject jsonObject = obj.getJSONObject("main");
System.out.println(jsonObject.get("temp"));

edited Apr 20, 2017 at 21:34

Peter Mortensen

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answered Apr 20, 2017 at 18:51

Narendra

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1 Comment

Peter Mortensen Over a year ago

A line that is nearly 900 characters long. Isn't there a better way?

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