getArguments() mengembalikan nol

getArguments() mengembalikan string JSON yang benar saat pertama kali OnCreateView() dipanggil untuk Frag1 tetapi tidak ketika saya menggeser ke Frag2 dan OnCreateView() untuk Frag1 dipanggil lagi. Sebaliknya, argumen "JSON" adalah nol.

Aktivitas:

SparkleViewPagerLayout sparkleViewPagerLayout = (SparkleViewPagerLayout) 
findViewById(R.id.view_pager_layout);
FragmentManager fm = getSupportFragmentManager();
sparkleViewPagerLayout.getViewPager().setAdapter(new FragmentPagerAdapter(fm) {
        @Override
        public int getCount() {
            return 4;
        }

        @Override
        public Fragment getItem(int pos) {
            switch (pos) {
                case 0:
                    return Frag0.newInstance(json0);
                case 1:
                    return Frag1.newInstance(json1); // <--THE FAILING FRAGMENT
                case 2:
                    return Frag2.newInstance(json2);
                case 3:
                    return Frag3.newInstance(json3);
                default:
                    return Frag0.newInstance(json0);
            }
        }
    });

Pecahan:

public class Frag1 extends Fragment {
private ArrayList<Thing> things;
private Gson gson = new Gson();

public static Frag1 newInstance(String json) {
    Bundle args = new Bundle();
    args.putString("JSON", json);
    args.putInt("background", R.drawable.img_thing_bg_blurred);
    Frag1 fragment = new Frag1();
    fragment.setArguments(args);

    return fragment;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.thing_detailed, parent, false);
    int background = getArguments().getInt("background");
    Util.setBackground(v, background, getContext());

    String json = getArguments().getString("JSON");
    things = gson.fromJson(json, new TypeToken<ArrayList<Thing>>() {
    }.getType());

    setUpThingOne(v);

    FragmentManager fm = getChildFragmentManager();
    Fragment listFragment = fm.findFragmentById(R.id.thingFragmentListContainer);
    // We removed the thing in position one, need to update the JSON to reflect this change.
    String jsonNew = gson.toJson(things);
    if (listFragment == null) {
        Bundle bundle = new Bundle();
        bundle.putString("THINGLIST", jsonNew);
        listFragment = new ThingListFragment();
        listFragment.setArguments(bundle);
        fm.beginTransaction()
                .add(R.id.ThingFragmentListContainer, listFragment)
                .commit();
    }

    return v;
}

    private void setUpThingOne(View v) {
        TextView name = (TextView) v.findViewById(R.id.thingName);
        TextView type = (TextView) v.findViewById(R.id.thingField);
        ImageView dollarImg = (ImageView) v.findViewById(R.id.thingPrice);
        ImageView bgImg = (ImageView) v.findViewById(R.id.thingBg);

        for (Thing thing : things) {
            if (thing.getPosition() == 1) {
                name.setText(thing.getName());
                type.setText(thing.getField());
                Util.setDollarImage(getContext(), dollarImg, thingSpot.getPrice());
                RequestUtil.getImage2(getContext(), thing.getImage_url(), bgImg);

                //Remove the #1 thing so that we can make a fragment list from the others.
                //things.remove(thing);
                break;
            }
        }
    }
}

Catatan kerusakan:

01-28 13:43:08.117 31378-31378/com.test.test E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.test.test, PID: 31378
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.Iterator java.util.ArrayList.iterator()' on a null object reference
       at com.test.test.fragments.Frag1.setUpThingOne(Frag1.java:78)
       at com.test.test.fragments.Frag1.onCreateView(Frag1.java:48)
       at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
       at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248)
       at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
       at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613)
       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:1106)
       at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
       at android.support.v4.view.ViewPager$3.run(ViewPager.java:251)
       at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
       at android.view.Choreographer.doCallbacks(Choreographer.java:670)
       at android.view.Choreographer.doFrame(Choreographer.java:603)
       at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
       at android.os.Handler.handleCallback(Handler.java:739)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5417)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)