Getting string from JSON response in Java

Question

Can't figure out how to get string of JSON response. From OpenWeatherMap API ( https://samples.openweathermap.org/data/2.5/forecast?id=524901&appid=b6907d289e10d714a6e88b30761fae22 ) want to get the first temp_min and temp_max.

I have tried to post the JSON response in a JSON formatter and go through it logically but that didn't help me much. Tried different solutions throughout google.

The last try from my side is this:

JSONObject jsonObject = new JSONObject(response);
JSONArray array = jsonObject.getJSONArray("list");
JSONObject firstObject = (JSONObject)array.get(0);
String tempmax = firstObject.getJSONObject("main").getString("temp_max");
String tempmin = firstObject.getJSONObject("main").getString("temp_min");

From the following API response, I want to receive temp_min and temp_max:

{  
   "cod":"200",
   "message":0.0032,
   "cnt":36,
   "list":[  
      {  
         "dt":1487246400,
         "main":{  
            "temp":286.67,
            "temp_min":281.556,
            "temp_max":286.67,
            "pressure":972.73,
            "sea_level":1046.46,
            "grnd_level":972.73,
            "humidity":75,
            "temp_kf":5.11
         },
         "weather":[  ],
         "clouds":{  },
         "wind":{  },
         "sys":{  },
         "dt_txt":"2017-02-16 12:00:00"
      },
[..]

I expect to get the temp_min and temp_max values from API response, but at the moment it's just empty.

I'm not getting an error, just the variables tempmax and tempmin are empty (blank), but I want that both values are read from the API request.In this case it should be like: tempmax = 286.67 tempmin = 281.556 — ksprs
– ksprs, Commented Apr 20, 2019 at 14:36
You might have a casting issue. Try cast this line to String (String)firstObject.getJSONObject("main").getString("temp_max"); I also suggest to add try catch to your code as if there is an error you are not capturing it — Tamir Klein
– Tamir Klein, Commented Apr 20, 2019 at 14:53

Michał Krzywański · Accepted Answer · 2019-04-20 14:48:41Z

I have just checked your code using this library with newest version. I loaded json content from local file and I had to change the way you read values of temperature :

    public static void main(String[] args) throws IOException {
        String collect = Files.lines(Paths.get("src/main/resources/waether.json")).collect(Collectors.joining());

        JSONObject jsonObject = new JSONObject(collect);
        JSONArray array = jsonObject.getJSONArray("list");
        JSONObject firstObject = (JSONObject)array.get(0);
        double tempmax = firstObject.getJSONObject("main").getDouble("temp_max");
        double tempmin = firstObject.getJSONObject("main").getDouble("temp_min");

        System.out.println("Temp min " + tempmin);
        System.out.println("Temp max " + tempmax);
    }

The output is :

Temp min 259.086
Temp max 261.45

As you see I had to use getDouble methods as those values were not json strings - they were numbers. I am not sure which version of this library you are using but with newest version it works.

ksprs · Accepted Answer · 2019-04-20 15:15:30Z

0

Big thanks to michalk and others for help. Edited michalk's answer a bit, so it meets my project and it solved the problem I was having.

answered Apr 20, 2019 at 15:15

ksprs

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