Tablayout bundle in fragment - null object reference

Question

I've used this guide here to make the activity: http://www.androidhive.info/2015/09/android-material-design-working-with-tabs

I have then added an AsyncTask.

I am trying to pass

Activity.java

private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFrag(new ProfileFragment(), "Profile");
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFrag(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

@Override
    protected void onPostExecute(String JSON_STRING_GET_ID) {
        try {
            JSONObject jsonResponse = new JSONObject(JSON_STRING_GET_ID);
            JSONArray jsonMainNode = jsonResponse.optJSONArray("server_response");

            for (int i = 0; i < jsonMainNode.length(); i++) {
                JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
                get_nav_email = jsonChildNode.optString("email");

                Bundle bundle = new Bundle();
                bundle.putString("p_email", get_nav_email);
                ProfileFragment fragToProfile = new ProfileFragment();
                fragToProfile.setArguments(bundle);

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

ProfileFragment.java:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View myInflatedView = inflater.inflate(R.layout.fragment_profile, container,false);

    String p_email = getArguments().getString("p_email");
    TextView txtTitle = (TextView)myInflatedView.findViewById(R.id.tvUsername2);
    txtTitle.setText(p_email);
    // Inflate the layout for this fragment
    return myInflatedView;
}

Here is the error I get:

1779-1779/com.testing.dev.application E/AndroidRuntime: FATAL EXCEPTION: main
                                                                              Process: com.testing.dev.application, PID: 1779
                                                                              java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                                                                                  at com.testing.dev.application.fragment.ProfileFragment.onCreateView(ProfileFragment.java:43)
                                                                                  at android.support.v4.app.Fragment.performCreateView(Fragment.java:1974)
                                                                                  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
                                                                                  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                                                                                  at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
                                                                                  at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                                                                                  at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570)
                                                                                  at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
                                                                                  at android.support.v4.view.ViewPager.populate(ViewPager.java:1177)
                                                                                  at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
                                                                                  at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:664)
                                                                                  at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:731)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                                                  at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                                                  at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                                                  at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                                                  at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                                                  at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
                                                                                  at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                                                  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
                                                                                  at android.view.View.measure(View.java:17547)
                                                                                  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2015)
                                                                                  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1173)
                                                                                  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1379)
                                                                                  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
                                                                                  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
                                                                                  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
                                                                                  at android.view.Choreographer.doCallbacks(Choreographer.java:580)
                                                                                  at android.view.Choreographer.doFrame(Choreographer.java:550)
                                                                                  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
                                                                                  at android.os.Handler.handleCallback(Handler.java:739)
                                                                                  at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                  at android.os.Looper.loop(Looper.java:135)
                                                                                  at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                                                  at java.lang.reflect.Method.invoke(Native Method)
                                                                                  at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

First of all, if you loop through an array inside onPostExecute like you are doing, you will overwrite the previous value and that doesn't seem like what you really want here. Also, you are not actually setting the fragment in view — Eenvincible, Apr 11 '16 at 15:50
@Eenvincible Can you tell me what you mean? I'm adding the fragment with the code setupViewPager and ViewPagerAdapter. I edited the OP. — Edward, Apr 11 '16 at 15:52

Eenvincible · Accepted Answer · 2016-04-11T16:41:06.833

1

I have an approach you might want to consider here! But of course, it is upon you.

Create your ViewPagerAdapter class and inside your addFrag() method, you want to pass the value of your email like this:

private String emailAddress;

public ViewPagerAdapter(FragmentManager manager, String email) {
    super(manager);
    emailAddress = email;
}

Thta is the constructor of your ViewPagerAdapter which you will create inside your Activity.

Within the same ViewPagerAdapter class, you will have this method addFrag

public void addFrag(Fragment fragment, String title) {
    Bundle bundle = new Bundle();
    //important line here to note
    bundle.putString("email", emailAddress);

    fragment.setArguments(bundle);
    mFragmentList.add(fragment);
    mFragmentTitleList.add(title);
}

Now that you are passing the email to the fragment, inside your onAttach method of the fragment, you can extract it and set as a class level variable.

@Override
public void onAttach(Context ctx){
    super.onAttach(ctx);



    String emailAddress = getArguments().getInt("email");

    //do whatever you need here
}

If however you want to update the fragment without a user touching the tabs, like later on after the AsyncTask has completed, you can look into using Events.

You basically let the fragment you want to update subscribe to a new Event from your AsyncTask's onPostExecute method.

My favorite library is using EventBus

Which you can simply add to your build.gradle file like this:

compile 'org.greenrobot:eventbus:3.0.0'

I hope this helps and please let me know if you need any further assistance!

edited Apr 11 '16 at 16:41

answered Apr 11 '16 at 16:18

Eenvincible

5,641
2
27
46

Thank you for all of that but that's not what I needed. I need to know why passing a string using bundle doesn't work and why I can't get it in the fragment. – Edward Apr 11 '16 at 16:29
Well, I think you are missing something with your code; but with your onPostExecute, you are simply creating a new instance of your fragment and setting the bundle then doing nothing with it! – Eenvincible Apr 11 '16 at 16:44
On onPostExecute, it is supposed to put information into the bundle and then on the fragment page, it is supposed to get it. – Edward Apr 11 '16 at 16:47
Yes but you created a new Fragment instance; meaning if there is already another fragment instance running, this will not work. You need to figure out a way to notify the already loaded fragment that there is new data to display; hence my Events approach! – Eenvincible Apr 11 '16 at 16:52
I will look into that. Thanks again! – Edward Apr 11 '16 at 16:55
I am willing to help you further if you want but then I will need to take a look at your code perhaps through gmail or somewhere – Eenvincible Apr 11 '16 at 16:56

iamtodor · Answer 2 · 2016-04-11T15:58:06.483

0

You are trying to getString from Bundle, when Bundle is null. Try to add checking if bundle is null:

String p_email = null;
if(getArguments() != null) {
    p_email = getArguments().getString("p_email");
}

edited Apr 11 '16 at 15:58

answered Apr 11 '16 at 15:54

iamtodor

734
8
21

Yes, that is checking if the argument is null or not. I want it to successfully pass the argument and then get it. I've tried doing this: bundle.putString("p_email", "Test string"); but it does not work either. – Edward Apr 11 '16 at 16:04
Do your tabs even change? – iamtodor Apr 11 '16 at 16:06
I mean if you comment those String, can you open fragment? – iamtodor Apr 11 '16 at 16:41
Yes, if I remove "getArguments" on the fragment page, I can open the fragment. – Edward Apr 11 '16 at 16:43

score 0 · Answer 3 · edited May 23 '17 at 12:15

0

You should pass arguments to the Fragment using setArguments method. Using newInstance method rather than the default constructor is generally recommended way to instantiate Fragments.

Refer to this and this.

edited May 23 '17 at 12:15

Community

1
1

answered Apr 11 '16 at 16:09

jaibatrik

6,770
9
33
62

Tablayout bundle in fragment - null object reference

3 Answers3