私のAndroidアプリにJSONからデータをフェッチしている間に、私はに起因する誤差ました：java.lang.NullPointerExceptionが：

Question

エラー

FATAL EXCEPTION: AsyncTask #1 
Process: com.example.brucewayne.weather, PID: 28994 
java.lang.RuntimeException: An error occurred while executing doInBackground() 
at android.os.AsyncTask$3.done(AsyncTask.java:309) 
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354) 
at java.util.concurrent.FutureTask.setException(FutureTask.java:223) 
at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) 
at java.lang.Thread.run(Thread.java:818) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference 
at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116) 
at org.json.JSONTokener.nextValue(JSONTokener.java:94) 
at org.json.JSONObject.<init>(JSONObject.java:156) 
at org.json.JSONObject.<init>(JSONObject.java:173) 
at Data.JSONWeatherParser.getWeather(JSONWeatherParser.java:22) 
at com.example.brucewayne.weather.MainActivity$WeatherTask.doInBackground(MainActivity.java:74) 
at com.example.brucewayne.weather.MainActivity$WeatherTask.doInBackground(MainActivity.java:69) 
at android.os.AsyncTask$2.call(AsyncTask.java:295) 
at java.util.concurrent.FutureTask.run(FutureTask.java:237) 
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)  
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)  
at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)  
at java.lang.Thread.run(Thread.java:818) 

私JSONWeatherParserクラス

public class JSONWeatherParser { 
public static Weather getWeather(String data){ 
    Weather weather = new Weather(); 
    //create Json object from data 
    try { 
     JSONObject jsonObject = new JSONObject(data); 
     Place place = new Place(); 
     JSONObject coordObj = Utils.getObject("coord",jsonObject); 
     place.setLat(Utils.getFloat("lat",coordObj)); 
     place.setLon(Utils.getFloat("lon",coordObj)); 

     //Get Sys Object in JSON web file http://samples.openweathermap.org/data/2.5/weather?q=London&appid=b1b15e88fa797225412429c1c50c122a1 

     JSONObject sysObj= Utils.getObject("sys",jsonObject); 
     place.setCountry(Utils.getString("country",sysObj)); 
     //dt is outside the sub branch in JSON so jsonObject used 
     place.setLastupdate(Utils.getInt("dt",jsonObject)); 
     place.setSunrise(Utils.getInt("sunrise",sysObj)); 
     place.getSunset(Utils.getInt("sunset",sysObj)); 
     place.setCity(Utils.getString("name",jsonObject)); 
     weather.place = place; 

     //get weather(its an array in jason file) info 

     JSONArray jsonArray = jsonObject.getJSONArray("weather"); 
     //"weather":[{"id":300(//0 is the index//),"main":"Drizzle","description":"light intensity drizzle","icon":"09d"}], 
     JSONObject jsonWeather = jsonArray.getJSONObject(0); 
     weather.currentCondition.setWeatherId(Utils.getInt("id",jsonWeather)); 
     weather.currentCondition.setDescription(Utils.getString("description",jsonWeather)); 
     weather.currentCondition.setCondition(Utils.getString("main",jsonWeather)); 
     weather.currentCondition.setIcon(Utils.getString("icon",jsonWeather)); 

     JSONObject windObj = Utils.getObject("wind",jsonObject); 
     weather.wind.setSpeed(Utils.getFloat("speed",windObj)); 
     weather.wind.setDeg(Utils.getFloat("deg",windObj)); 

     JSONObject cloudObj = Utils.getObject("clouds",jsonObject); 
     weather.clouds.setPrecipitation(Utils.getInt("all",cloudObj)); 

     return weather; 


    } catch (JSONException e) { 
     e.printStackTrace(); 

    } 
    return null; 

    } 
} 

私redererと非同期

public void renderWeatherData(String city){ 
    WeatherTask weatherTask = new WeatherTask(); 
    weatherTask.execute(new String[]{city + "&units=metric"}); 
} 

private class WeatherTask extends AsyncTask<String,Void, Weather>{ 
    @Override 
    protected Weather doInBackground(String... strings) { 

     String data = ((new WeatherHttpClient()).getWeatherData(strings[0])); 
     weather = JSONWeatherParser.getWeather(data); 


     Log.v("Data:",weather.currentCondition.getDescription()); 

     return weather; 
    } 

    @Override 
    protected void onPostExecute(Weather weather) { 
     super.onPostExecute(weather); 
    } 
} 

Answer 1

なぜ文字列配列をexecuteメソッドに渡しますか？ STIL動作していない

weatherTask.execute(city + "&units=metric");