access elementsJSON array in Java

Question

I am new to JSON. I know the forecast is an array, but how do I access elements date and text? I know where the problem is: It seems i cannot get access to forecast array, as this gives a null.

JSONArray jArr = data.getJSONArray("forecast");

what is the proper notation to get access to the forecast array. I was trying

`JSONArray jArr = data.getJSONObject("item").getJSONObject("condition").getJSONArray("forecast");

but this notation still did not give me access to the array. What notation will give me correct reference to forecast array?

 "item": {
 "title": "Conditions for Kingston, Saint Andrew, JM at 09:00 PM EST",
 "lat": "18.015711",
 "long": "-76.79731",
 "link": "http://us.rd.yahoo.com/dailynews/rss/weather/Country__Country/*https://weather.yahoo.com/country/state/city-109251/",
 "pubDate": "Sat, 22 Oct 2016 09:00 PM EST",
 "condition": {
  "code": "27",
  "date": "Sat, 22 Oct 2016 09:00 PM EST",
  "temp": "77",
  "text": "Mostly Cloudy"
 },
 "forecast": [
  {
   "code": "32",
   "date": "20 Oct 2016",
   "day": "Thu",
   "high": "35",
   "low": "26",
   "text": "Sunny"
  },
  {
   "code": "34",
   "date": "21 Oct 2016",
   "day": "Fri",
   "high": "34",
   "low": "28",
   "text": "Mostly Sunny"
  },
  {
   "code": "26",
   "date": "22 Oct 2016",
   "day": "Sat",
   "high": "37",
   "low": "32",
   "text": "Cloudy"
  },
  {
   "code": "23",
   "date": "23 Oct 2016",
   "day": "Sun",
   "high": "37",
   "low": "34",
   "text": "Breezy"
  },

I was trying something like this, but my android app was crashing? I just need help in accessing the elements in the array to set them on some textfields.

public void populate(JSONObject data) throws JSONException {

    JSONArray jArr = data.getJSONArray("forecast");

    for(int i=0;i<jArr.length();i++){
        JSONObject jDayForecast = jArr.getJSONObject(i);
        String date =  jDayForecast.getString("date");
        String text =  jDayForecast.getString("text");
    }
}

here is the error in stacktrace.

54.516 27220-27220/net.digitalphantom.app.weatherapp E/AndroidRuntime: FATAL EXCEPTION: main
                                                                               Process: net.digitalphantom.app.weatherapp, PID: 27220
                                                                               java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String net.JamCast.app.weatherapp.data.Forecast.getDate()' on a null object reference
                                                                                   at net.JamCast.app.weatherapp.WeatherActivity$override.serviceSuccess(WeatherActivity.java:363)
                                                                                   at net.JamCast.app.weatherapp.WeatherActivity$override.access$dispatch(WeatherActivity.java)
                                                                                   at net.JamCast.app.weatherapp.WeatherActivity.serviceSuccess(WeatherActivity.java:0)
                                                                                   at net.JamCast.app.weatherapp.service.YahooWeatherService$1.onPostExecute(YahooWeatherService.java:95)
                                                                                   at net.JamCast.app.weatherapp.service.YahooWeatherService$1.onPostExecute(YahooWeatherService.java:37)
                                                                                   at android.os.AsyncTask.finish(AsyncTask.java:651)
                                                                                   at android.os.AsyncTask.access$500(AsyncTask.java:180)
                                                                                   at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                   at android.os.Looper.loop(Looper.java:158)
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:7229)
                                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

If the app is crashing, please include the stacktrace. Your code looks fine though — 0xDEADC0DE, Oct 20 '16 at 13:47
please note that your JSON is incomplete such that it is not even parseable. — Nicolas Filotto, Oct 20 '16 at 13:53
Also note that your crash occurs somewhere else than in your posted code — 0xDEADC0DE, Oct 20 '16 at 14:08
Possible duplicate of [What is a NullPointerException, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — 0xDEADC0DE, Oct 20 '16 at 14:10
@0xDEADC0DE please look at my update to my problem, it seems i cannot get correct reference to the forecast array. — JohnnyCage, Oct 23 '16 at 03:07

score 0 · Answer 1 · answered Oct 20 '16 at 13:52

0

define a java bean class, use GSON jar translate json string to class object, then you can get text element by your object. please search in google sample.

answered Oct 20 '16 at 13:52

yan

41
4

access elementsJSON array in Java

1 Answers1