NullPointerException with bundle and AsyncHttpTask

Question

In my Android app I have a messages activity that is composed by three tabs (fragments: inbox, sent and deleted). I need to load data (received in JSON format and converted to String) in both tabs, but when I load the fragments app throws NullPointerException in the line where data is put in the bundle. I think that it's because the app hasn't received the information at the moment of its invocation.

To connect with the service provider i am using AsyncHttpTask library. Here is my code:

MessagesActivity.java:

public class MessagesActivity extends AppCompatActivity {
Toolbar toolbar;
ViewPager pager;
MessagesTabAdapter adapter;
SlidingTabLayout tabs;
CharSequence tabsTitles[] = {"Inbox","Sent","Trash"};
int tabsNumber = 3;
JSONObject inbox;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.messages_activity);

    //Elements initialization
    ...
    adapter =  new MessagesTabAdapter(getSupportFragmentManager(), tabsTitles, tabsNumber);

    // Assigning ViewPager View and setting the adapter
    pager = (ViewPager) findViewById(R.id.messages_pager);
    pager.setAdapter(adapter);

    // Assiging the Sliding Tab Layout View
    tabs = (SlidingTabLayout) findViewById(R.id.messages_tabs);
    tabs.setDistributeEvenly(true);

    // Setting Custom Color for the Scroll bar indicator of the Tab View
    tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
        @Override
        public int getIndicatorColor(int position) {
            return getResources().getColor(R.color.tabsScrollColor);
        }
    });

    // Setting the ViewPager For the SlidingTabsLayout
    tabs.setViewPager(pager);
}

public void updateInbox () {
    String token = getSharedPreferences("Myapp", Context.MODE_PRIVATE).getString("token", null);

    RequestParams params = new RequestParams();
    params.add("token", token);
    Client.get("get_inbox", params, new JsonHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
            try {
                inbox = response.getJSONObject("result");
            } catch (JSONException e) {
                //No messages
                inbox = new JSONObject();
            }
        }
    });
}

public class MessagesTabAdapter extends FragmentStatePagerAdapter {

    ...

    //This method return the fragment for the every position in the View Pager
    @Override
    public Fragment getItem(int position) {

        if(position == 0) // if the position is 0 we are returning the First tab
        {
            Bundle bundle = new Bundle();
            bundle.putString("inbox", updateInbox().toString()); //HERE IS MY EXCEPTION!
            MessagesInboxTab tab1 = new MessagesInboxTab();
            tab1.setArguments(bundle);
            return tab1;
        }
        else if(position == 1) // As we are having 2 tabs if the position is now 0 it must be 1 so we are returning second tab
        {
            //Here will go the same code as position==0
            MessagesSentTab tab2 = new MessagesSentTab();
            return tab2;
        }
        else
        {
            //Here will go the same code as position==0
            MessagesTrashTab tab3 = new MessagesTrashTab();
            return tab3;
        }
    }

    ...
}

How can I solve?

score 0 · Answer 1 · answered Sep 13 '15 at 11:56

0

You are getting null inside your updateInbox() method because you return null at its end, I think you wanted to return something else but you forgot to write it :)

answered Sep 13 '15 at 11:56

SaNtoRiaN

2,212
2
15
25

I have updated my code (please check above), an I am getting the same exception. – Angel F. Sep 14 '15 at 05:50
@AngelSanchez Where exactly is the exception? because this code is wrong `bundle.putString("inbox", updateInbox().toString());` as the `updateInbox()` return type is void and you are converting it to string – SaNtoRiaN Sep 14 '15 at 16:40
I have decided to put AsyncHttpTask into tab directly, although I don't like this solution. Thanks anyway! – Angel F. Sep 15 '15 at 07:49

score 0 · Answer 2 · answered Sep 13 '15 at 11:57

0

The following method, always returning a null value.

public JSONObject updateInbox () {
String token = getSharedPreferences("Myapp", Context.MODE_PRIVATE).getString("token", null);

RequestParams params = new RequestParams();
params.add("token", token);
Client.get("get_inbox", params, new JsonHttpResponseHandler() {
    @Override
    public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
        try {
            inbox = response.getJSONObject("result");
        } catch (JSONException e) {
            //No messages
            inbox = null;
        }
    }
});
return null;

}

You should return inbox inside the try block.

answered Sep 13 '15 at 11:57

lmanohara

77
8

Yes, but inbox variable is into onSuccess method, null value doens't matter. I have update the code. – Angel F. Sep 14 '15 at 05:51
Returning Null values is not the problem, but you are not returning the object and trying to call the toString method. The meaning of the null-pointer exception is without initiating a object, try to call a method of that class. – lmanohara Sep 14 '15 at 17:21
I have decided to put AsyncHttpTask into tab directly to avoid this problem, although I don't like this solution. Thanks anyway! – Angel F. Sep 15 '15 at 07:50

NullPointerException with bundle and AsyncHttpTask

2 Answers2