IllegalStateException mit PagerAdapter

Habe ich ähnliche Probleme wie du hast, ich habe viewpager auf Eine Aktivität dann, wenn Benutzer auf das Element in der viewpager, wird er zur Aktivität B, die viewpager zu. Wenn der Benutzer die zurück von Aktivität B Aktivität A, Sie werden werfen, Ausnahme wie hier:

java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 4, found: 0 Pager id: com.gbu.app.templateforbussiness:id/header_view_pager_list Pager class: class android.support.v4.view.ViewPager Problematic adapter: class com.gbu.app.templateforbussiness.adapter.DetailProductPagerAdapter

Ich denke, das problem ist, die Inhalte der Daten, dass der adapter von der viewpager haben immer 0, da der adapter nicht über die Daten, die übergeben durch die von der Tätigkeit. Also habe ich versucht es funktioniert wie in diesem Beispiel:

DetailProductActivity.class

public class DetailProductActivity extends FragmentActivity {
    private ViewPager product_detail_viewpager;
    private DetailProductPagerAdapter detail_product_adapter;
    private Intent product_detail_intent;
    public static List<Product> detail_product;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail_product);
        product_detail_viewpager = (ViewPager) findViewById(R.id.detail_product_viewpager);
        detail_product = HomeActivity.home_product;
    }

    @Override
    protected void onStart() {
        super.onStart();
        product_detail_intent = getIntent();
        startApp(product_detail_intent);
    }

    @Override
    protected void onStop() {
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
    }

    private void startApp(Intent data) {
        //TODO Auto-generated method stub
            //pass the Array, List of data to viewpager adapter like this
        detail_product_adapter = new DetailProductPagerAdapter(getSupportFragmentManager(), detail_product); 
        product_detail_viewpager.setAdapter(detail_product_adapter);
        product_detail_viewpager.setCurrentItem(data.getIntExtra("current_item", 0));
    }

}

Dem adapter der viewpager:
DetailProductPagerAdapter.class

public class DetailProductPagerAdapter extends FragmentPagerAdapter {
    private ProductDetailFragment detail_product_fragment;
    private Bundle data;
    private List<Product> detail_product;

    //the data from Activity passed to this adapter        
    public DetailProductPagerAdapter(FragmentManager fm, List<Product> p) {
        super(fm);
        //TODO Auto-generated constructor stub
        detail_product = p;
    }

    //then passing the data again to your fragment class, like this example
    @Override
    public Fragment getItem(int arg0) {
        //TODO Auto-generated method stub
        detail_product_fragment = new ProductDetailFragment(detail_product);
        data = new Bundle();
        data.putInt("current_item", arg0);
        detail_product_fragment.setArguments(data);
        return detail_product_fragment;
    }

    @Override
    public int getCount() {
        //TODO Auto-generated method stub
        return detail_product.size();
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }   

}

- Und die fragment-Klasse:
ProductDetailFragment.class

@SuppressLint("ValidFragment")
public class ProductDetailFragment extends Fragment {
    private RelativeLayout detail_item_header;
    private ImageView detail_item_imv;
    private TextView detail_item_tv_title;
    private WebView detail_item_web_content;
    private DisplayMetrics detail_metrics;
    private List<Product> detail_product;
    private int index_item;

    //the data from adapter pass it to this fragment
    public ProductDetailFragment(List<Product> p) {
        detail_product = p;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View view_detail = inflater.inflate(R.layout.item_product_detail_viewpager, container, false);
        detail_metrics = new DisplayMetrics();
        getActivity().getWindowManager().getDefaultDisplay().getMetrics(detail_metrics);
        savedInstanceState = getArguments();
        index_item = savedInstanceState.getInt("current_item");
        detail_item_header = (RelativeLayout) view_detail.findViewById(R.id.item_header_product_viewpager);
        detail_item_imv = (ImageView) detail_item_header.findViewById(R.id.item_imv_product_viewpager);
        detail_item_tv_title = (TextView) detail_item_header.findViewById(R.id.item_tv_title_product_viewpager);
        detail_item_web_content = (WebView) view_detail.findViewById(R.id.item_web_product_viewpager);
        startApp();
        return view_detail;
    }

    private void startApp() {
        //TODO Auto-generated method stub
        detail_item_header.getLayoutParams().height = (int) (detail_metrics.heightPixels * 0.38);
        if (detail_product.get(index_item).getStatus() == 0) {
            new loadImageProduct(detail_item_imv).execute(detail_product.get(index_item).getImage());
        }else {
            detail_item_imv.setImageBitmap(detail_product.get(index_item).getBmp());
        }
        detail_item_tv_title.setText(detail_product.get(index_item).getTitle());
        String web_content_product = "<!DOCTYPE html>"+
                                     "<html>"+
                                     "<body>"+
                                     "<p>Harga : "+detail_product.get(index_item).getPrice()+"</p><br>"+
                                     detail_product.get(index_item).getDetail()+"<br><br>"+
                                     detail_product.get(index_item).getDetail2()+
                                     "</body>"+
                                     "</html>";
        detail_item_web_content.loadDataWithBaseURL("https://www.google.com", web_content_product, "text/html", "UTF-8", null);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }

    private class loadImageProduct extends AsyncTask<String, Integer, Bitmap> {
        private Bitmap b;
        private ImageView vimv;
        private GetImage get_image;

        public loadImageProduct(ImageView v) {
            vimv = v;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            b = null;
            get_image = new GetImage();
        }

        @Override
        protected Bitmap doInBackground(String...url) {
            try {
                b = get_image.loadImageFromServer(url[0]);
                if (b != null)
                    return b;
            } catch(OutOfMemoryError e) {

            }
            return b;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            super.onPostExecute(result);
            if (result != null) {
                detail_product.get(index_item).setBmp(result);
                detail_product.get(index_item).setStatus(1);
                vimv.setImageBitmap(result);
            }
        }
    }

}

Jetzt die Ausnahme, bevor es zeigt nicht mehr und der viewpager normal arbeitet. Diese Methode versucht, machen den viewpager wie listview habe, weil listview haben, die Weitergabe der Daten durch den adapter so, dass die adapter nicht verlieren, die Inhalte der Daten selbst die Daten geändert haben. Ich hoffe, dieses Beispiel hilft, Ihre Probleme. Cheers.

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