java.lang.runtimeexception error occurred while executing doinbackground() caused by NPE

Question

Whenever I open my app, it crashes and gives me the following logcat errors. I do not know where I have gone wrong. I wanted to know why my application crashes and how can I fix it.

??-?? ??:??:??.???: INFO/<unknown>(<unknown>): java.lang.RuntimeException: An error occured while executing doInBackground()
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.lang.Thread.run(Thread.java:841)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>): Caused by: java.lang.NullPointerException
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at com.example.gravitas2015.MainActivity$jsonhandler.handleResponse(MainActivity.java:284)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at com.example.gravitas2015.MainActivity$jsonhandler.handleResponse(MainActivity.java:1)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:657)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:627)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:616)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at android.net.http.AndroidHttpClient.execute(AndroidHttpClient.java:273)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at com.example.gravitas2015.MainActivity$request.doInBackground(MainActivity.java:250)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at com.example.gravitas2015.MainActivity$request.doInBackground(MainActivity.java:1)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
??-?? ??:??:??.???: INFO/<unknown>(<unknown>):     ... 4 more

Here's my code for doInBackground

private class request extends AsyncTask<Void, Void, List<String>>{


        AndroidHttpClient client= AndroidHttpClient.newInstance("");
        HttpGet request;

        @Override
        protected List<String> doInBackground(Void... arg0) {
            if (isOnline())
            {
                try{

                    request = new HttpGet("http://www.com");

                }catch(NullPointerException e ){
                    e.printStackTrace();}
                jsonhandler handler = new jsonhandler();
                try
                {
                    return client.execute(request,handler);
                }catch(ClientProtocolException exception){
                    exception.printStackTrace();
                }catch(IOException exception){
                    exception.printStackTrace();
                }

            }
            return null;
        }
        protected void onPostExecute(List<String> result)
          {
            super.onPostExecute(result);
            if (this.client != null) {
              this.client.close();
            }
          }

    }
private class jsonhandler implements ResponseHandler<List<String>>{
    @Override
    public List<String> handleResponse(HttpResponse response)
            throws ClientProtocolException, IOException {

        List<String> result = new ArrayList<String>();
        String jsonresponse = new BasicResponseHandler().handleResponse(response);
        int i;
        JSONArray data;
        try {

            data = new JSONArray(jsonresponse);
            for(i=0;i<data.length();i++)
            {
                JSONObject obj = (JSONObject)data.get(i);
                tid[i]=Integer.parseInt(obj.get("tid").toString());
                name[i]=obj.get("name").toString();
                org[i]=obj.get("organisation").toString();
                desc[i]=obj.getString("description").toString();
                date[i]=obj.get("date").toString();
                time[i]=obj.get("timings").toString();
                loc[i]=obj.get("location").toString();
                fee[i]=obj.get("fee").toString();
                cname1[i]=obj.get("cname1").toString();
                pho1[i]=obj.get("cno1").toString();
                cname2[i]=obj.get("cname2").toString();
                pho2[i]=obj.get("cno2").toString();
                email[i]=obj.get("email").toString();
                team[i]=obj.get("team").toString();


                result.add("EVENT: "+name[i]+"\nDATE: "+date[i]+"\nVENUE: "+loc[i]+"\n");
            }
            k=i;
        }catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return result;
    }


}

https://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it — Karakuri, Jul 23 '15 at 05:14
I did. It was the first fetch statement tid[i]=Integer.parseInt(obj.get("tid").toString()); — Steve Mathews, Jul 23 '15 at 05:18
@Karakuri could you tell me how to avoid this specific NPE issue? — Steve Mathews, Jul 23 '15 at 05:20
@SteveMathews Something on the line specified is `null`, you need to figure out what. It could either be `tid`, `obj`, or the result of `obj.get("tid")`. — Karakuri, Jul 23 '15 at 05:27
i think `response` value is `null` as your `http://www.com` is not a valid address to get JSON data. — Anand Singh, Jul 23 '15 at 05:29
That's just for confidentiality. There is an actual link. :D — Steve Mathews, Jul 23 '15 at 05:39
Do null check of your response and print what is coming in your data . check the length of your json array. Do null checks where ever you are getting your data. Debug the code and see where the control is going and you will find exactly where it is failing. You can start using google's own volley library's GsonRequest class and you will be free from the entire hassle of parsing the response etc. GsonRequest will automatically set the setter methods of your result model class — Kaveesh Kanwal, Jul 23 '15 at 06:06

score 0 · Accepted Answer · answered Jul 23 '15 at 05:22

0

in your try block you say

request = new HttpGet("http://gravitas-eshwa.rhcloud.com/eventapi.php");

if this fails you catch NullPointerException and do

jsonhandler handler = new jsonhandler();

try
   {
       return client.execute(request,handler);
   }catch(ClientProtocolException exception){
         exception.printStackTrace();
   }catch(IOException exception){
       exception.printStackTrace();
   }

So you simply proceed to

return client.execute(request,handler);

when you have just caught request as null, which causes the error. So you have to add something to the first catch to react to the null request.

answered Jul 23 '15 at 05:22

milez

2,201
12
31

Should I put another catch for NPE then? But then again, why am I getting a null request? I can see the data and it's fine – Steve Mathews Jul 23 '15 at 05:27
So you checked `request` is not null? – milez Jul 23 '15 at 05:28
And NPE is at line 284 where I am fetching the first time tid[i]=Integer.parseInt(obj.get("tid").toString()); – Steve Mathews Jul 23 '15 at 05:29
That is because data is null, because jsonresponse is null, because response is null, because request is null – milez Jul 23 '15 at 05:31
I just put another catch statement for NPE now. Didn't solve – Steve Mathews Jul 23 '15 at 05:32
Haha. That's just for displaying here. Have a working link – Steve Mathews Jul 23 '15 at 05:38
I see :p well debug and see that the value you get to request is not null. If there is valid data then I dont know.. – milez Jul 23 '15 at 05:40
It works now! For some reason it worked from the third time I tried. Thanks a lot! I had worked on Json before and had the catch there. Don't know how I missed it. Another issue now is that I'm not getting all the data. – Steve Mathews Jul 23 '15 at 05:50
Did you try and do a null check on your data. Check the length of your JSONArray data before you start parsing the result data. – Kaveesh Kanwal Jul 23 '15 at 05:51
Good to hear. Data problem sounds like another question of there is nothing similar on the site yet :p – milez Jul 23 '15 at 05:51
1

Moreover i will suggest to you that please start using google's own volley library's GsonRequest class and you will be free from the entire hassle of parsing the response etc. GsonRequest will automatically set the setter methods of your result model class. – Kaveesh Kanwal Jul 23 '15 at 05:58
@Milez I did just that. Seems perfect. 160. But doesn't fetch the entire data – Steve Mathews Jul 23 '15 at 06:03
@Kaveesh, will do henceforth. Thanks for the advice :) – Steve Mathews Jul 23 '15 at 06:04
Ok, if you need any help using volley do let me know, i have used GsonRequest and other class, i can help you with the code if you want – Kaveesh Kanwal Jul 23 '15 at 06:09
Could you just help me out with this? I no longer can fetch data. All values show null but the traversal happens 160 times. The data just doesn't store. – Steve Mathews Jul 23 '15 at 06:14
Now it won't even traverse. Wow – Steve Mathews Jul 23 '15 at 06:15
can you show your log so that we can see what exactly is coming in the JSONArray? – Kaveesh Kanwal Jul 23 '15 at 06:47
log while opening the application? – Steve Mathews Jul 23 '15 at 10:05
Solved it. Thanks anyways! (y) – Steve Mathews Jul 23 '15 at 10:48

java.lang.runtimeexception error occurred while executing doinbackground() caused by NPE

1 Answers1