Null pointer Exception in asynctask

Question

Please help me why i'm getting this error. I'm getting Json response converting into string using convertStreamToString method getting correct string, I can able to see this string in my logcat.
Now i'm trying to insert my json response string to sqlite database, for that i'm using

JSONObject HabitatObject = MyHabitatJsonObject.getJSONObject("HabitatDetails");    
JSONObject HabitatPosts = HabitatObject.getJSONObject("habitat");
    JSONArray HabitatPostsArray = HabitatPosts.getJSONArray("Post");
        ContentValues values = new ContentValues();
         DatabaseHelper InsertHabitat;     
        for (int i = 0; i < HabitatPostsArray.length(); i++) {
         values.put(InsertHabitat.PostUserImage, HabitatPostsArray.getJSONObject(i).getString("userimage").toString());
         values.put(InsertHabitat.PostUserName, HabitatPostsArray.getJSONObject(i).getString("username").toString());
    dbHabitat.insert(InsertHabitat.HABITATTABLE, null, values);
                }

Till now every thing is fine but when i'm trying to insert these values into database i'm getting error on this line
values.put(InsertHabitat.PostUserImage, HabitatPostsArray.getJSONObject(i).getString("userpostimage").toString());

Error Log:

12-10 10:57:19.872: E/AndroidRuntime(301): FATAL EXCEPTION: AsyncTask #3
12-10 10:57:19.872: E/AndroidRuntime(301): java.lang.RuntimeException: An error occured while executing doInBackground()
12-10 10:57:19.872: E/AndroidRuntime(301):  at android.os.AsyncTask$3.done(AsyncTask.java:200)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.lang.Thread.run(Thread.java:1096)
12-10 10:57:19.872: E/AndroidRuntime(301): Caused by: java.lang.NullPointerException
12-10 10:57:19.872: E/AndroidRuntime(301):  at com.UserLogin.Habitat$HabitatResults.doInBackground(Habitat.java:90)
12-10 10:57:19.872: E/AndroidRuntime(301):  at com.UserLogin.Habitat$HabitatResults.doInBackground(Habitat.java:1)
12-10 10:57:19.872: E/AndroidRuntime(301):  at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-10 10:57:19.872: E/AndroidRuntime(301):  ... 4 more

Answer 1

I think that this is null

HabitatPostsArray.getJSONObject(i).getString("userpostimage")

Have you tried to print that value? Check the values before that line, basic checks like:

JSONObject jo = HabitatPostsArray.getJSONObject(i);

if (jo == null)
    Log.d("tag", "json obj null "+i);
if (!jo.has("userpostimage"))
    Log.d("tag", "key not present, you are not parsing correctly the json");

String s = jo.getString("userpostimage");
if (s == null)
    Log.d("tag", "userpostimage null");

Answer 2

Try Logging your JsonObject [jo], are you getting values there? JSONObject jo = HabitatPostsArray.getJSONObject(i);

if (jo == null)
    Log.d("tag", "json obj null "+i);
else 
    Log.d("tag", "json object at index" + i + " is : " + jo.toString());