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POview pager sometimes show empty
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  1. POview pager sometimes show empty
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    copied!<p>I use <a href="https://github.com/astuetz/PagerSlidingTabStrip" rel="nofollow">PagerSlidingTabStrip library</a> but I have a problem with this library. I have a <code>GridView</code> that gets updated from the web by an <code>AsyncTask</code> when the page is changed. My problem is that the first page is empty. When I click on tab 2 the content shows up, but if I click on tab 3 when tab 1 is selected (move to tab from selected tab) the page also is empty. It only works well if I swipe the pages one by one or click on "next tab" (move one tab form selected tab) .</p> <p>Why is the page sometimes empty?</p> <p>The library sample app works correctly but it changes view on creation. My code is different because the grid view is updated in AsyncTask by change page selected.</p> <p>The code for <strong>subCategoryActivity.java</strong>:</p> <pre><code> public class SubCategoryActivity extends SherlockFragmentActivity { static SubCategoryObjectsFragment f; private PagerSlidingTabStrip tabs; private ViewPager pager; private MyPagerAdapter pagerAdapter; TextView tvCustomTitle; static List&lt;NameValuePair&gt; nameValuePairs = new ArrayList&lt;NameValuePair&gt;(); static JSONArray jsonArray; static String url = "http://192.168.1.2/arel/SubCat.php"; static String url2 = "http://192.168.1.2/arel/subCatObject.php"; private static String[][] SubCat; GridviewAdapter gridAdapter; static GridView gridViewSubCategory; HashMap&lt;String, String&gt; map; static ArrayList&lt;HashMap&lt;String, String&gt;&gt; list = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;(); Intent intent; private class getSubCategoryObjects extends AsyncTask&lt;String, Void, String&gt; { @Override protected String doInBackground(String... url) { // TODO Auto-generated method stub return BaseActivity.jsonParser.makeHttpRequest(url[0], "POST", nameValuePairs); } @Override protected void onProgressUpdate(Void... values) { // TODO Auto-generated method stub super.onProgressUpdate(values); } @Override protected void onPostExecute(String result) { // TODO Auto-generated method stub try { jsonArray = new JSONArray(result); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } for (int i = 0; i &lt; jsonArray.length(); i++) { JSONObject jsonObjet; map = new HashMap&lt;String, String&gt;(); try { jsonObjet = jsonArray.getJSONObject(i); map.put("id", String.valueOf(jsonObjet.getInt("id"))); map.put("title", jsonObjet.getString("title_fa")); map.put("image", jsonObjet.getString("image")); map.put("price", jsonObjet.getString("price")); map.put("date", jsonObjet.getString("date")); list.add(map); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } gridAdapter = new GridviewAdapter(SubCategoryActivity.this, list); gridViewSubCategory.setAdapter(gridAdapter); } } private class getSubCategory extends AsyncTask&lt;String, Void, String&gt; { @Override protected String doInBackground(String... url) { // TODO Auto-generated method stub return BaseActivity.jsonParser.makeHttpRequest(url[0], "POST", nameValuePairs); } @Override protected void onProgressUpdate(Void... values) { // TODO Auto-generated method stub super.onProgressUpdate(values); } @Override protected void onPostExecute(String result) { // TODO Auto-generated method stub try { jsonArray = new JSONArray(result); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } SubCat = new String[jsonArray.length()][2]; for (int i = 0; i &lt; jsonArray.length(); i++) { JSONObject jsonObjet; try { jsonObjet = jsonArray.getJSONObject(i); SubCat[i][0] = String.valueOf(jsonObjet.getInt("id")); SubCat[i][1] = jsonObjet.getString("title_fa"); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { // TODO: handle exception e.toString(); } } pagerAdapter = new MyPagerAdapter(getSupportFragmentManager()); pager.setAdapter(pagerAdapter); // pager.setCurrentItem(0); //pager.setOffscreenPageLimit(0); tabs.setOnPageChangeListener(new OnPageChangeListener() { @Override public void onPageSelected(int arg0) { // TODO Auto-generated method stub jsonArray = new JSONArray(); list = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;(); nameValuePairs = new ArrayList&lt;NameValuePair&gt;(); nameValuePairs.add(new BasicNameValuePair("getAdvertise", "true")); nameValuePairs.add(new BasicNameValuePair("subCatId", SubCat[arg0][0])); // Activity myActivity = getActivity(); // if (myActivity instanceof SubCategoryActivity) { new getSubCategoryObjects().execute(url2); } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { // TODO Auto-generated method stub } @Override public void onPageScrollStateChanged(int arg0) { // TODO Auto-generated method stub } }); //jsonArray = new JSONArray(); // final int pageMargin = (int) TypedValue.applyDimension( // TypedValue.COMPLEX_UNIT_DIP, 16, getResources() // .getDisplayMetrics()); // pager.setPageMargin(pageMargin); tabs.setViewPager(pager); tabs.setTextSize(20); tabs.setTypeface(BaseActivity.font, Typeface.NORMAL); // list = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;(); // nameValuePairs = new ArrayList&lt;NameValuePair&gt;(); // nameValuePairs.add(new BasicNameValuePair("getAdvertise", "true")); // nameValuePairs.add(new BasicNameValuePair("subCatId", // SubCat[0][0])); //new getSubCategoryObjects().execute(url2); } } @SuppressLint("NewApi") @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_list); intent = getIntent(); tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs); pager = (ViewPager) findViewById(R.id.pager); jsonArray = new JSONArray(); nameValuePairs = new ArrayList&lt;NameValuePair&gt;(); nameValuePairs.add(new BasicNameValuePair("getSubCategory", "true")); nameValuePairs.add(new BasicNameValuePair("catId", intent .getStringExtra("id"))); new getSubCategory().execute(url); getSupportActionBar().setDisplayHomeAsUpEnabled(true); getSupportActionBar().setDisplayShowTitleEnabled(false); getSupportActionBar().setDisplayShowCustomEnabled(true); tvCustomTitle = new TextView(this); tvCustomTitle.setText(intent.getStringExtra("title")); LinearLayout ll = new LinearLayout(this); LinearLayout.LayoutParams para = new LinearLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); para.setMargins(0, 0, 0, 0); // left,top,right, bottom para.gravity = Gravity.CENTER_VERTICAL; tvCustomTitle.setTypeface(BaseActivity.font); Configuration config = getResources().getConfiguration(); if (Build.VERSION.SDK_INT &gt;= 13) { if (config.smallestScreenWidthDp &gt;= 600) { tvCustomTitle.setTextSize(22); } else { tvCustomTitle.setTextSize(14); } } else { tvCustomTitle.setTextSize(14); } tvCustomTitle.setTextColor(Color.WHITE); ll.addView(tvCustomTitle, para); getSupportActionBar().setCustomView(ll); changeColor(intent.getIntExtra("color", Color.parseColor("#FF666666"))); } private void changeColor(int newColor) { tabs.setIndicatorColor(newColor); // change ActionBar color just if an ActionBar is available Drawable colorDrawable = new ColorDrawable(newColor); Drawable bottomDrawable = getResources().getDrawable( R.drawable.actionbar_bottom); LayerDrawable ld = new LayerDrawable(new Drawable[] { colorDrawable, bottomDrawable }); getSupportActionBar().setBackgroundDrawable(ld); } /* * @Override protected void onSaveInstanceState(Bundle outState) { * super.onSaveInstanceState(outState); * * } * * @Override protected void onRestoreInstanceState(Bundle * savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); * * } */ public static class MyPagerAdapter extends FragmentStatePagerAdapter { public MyPagerAdapter(FragmentManager fm) { super(fm); } @Override public CharSequence getPageTitle(int position) { return SubCat[position][1]; } @Override public int getCount() { return SubCat.length; } @Override public Fragment getItem(int position) { f = new SubCategoryObjectsFragment(); Bundle b = new Bundle(); b.putString(SubCategoryObjectsFragment.ARG_ID, SubCat[position][0]); f.setArguments(b); return f; } } public static class SubCategoryObjectsFragment extends Fragment { private static final String ARG_ID = "id"; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate( R.layout.fragment_sub_category_objects, container, false); // gridViewSubCategory = new GridView(getActivity()); gridViewSubCategory = (GridView) rootView.findViewById(R.id.gridViewSubCategory); return rootView; } @Override public void onActivityCreated(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onActivityCreated(savedInstanceState); /* * jsonArray = new JSONArray(); list = new ArrayList&lt;HashMap&lt;String, * String&gt;&gt;(); nameValuePairs = new ArrayList&lt;NameValuePair&gt;(); * nameValuePairs.add(new BasicNameValuePair("getAdvertise", * "true")); nameValuePairs.add(new BasicNameValuePair("subCatId", * getArguments().getString("id"))); * * * Activity myActivity = getActivity(); if (myActivity instanceof * SubCategoryActivity) { ((SubCategoryActivity) myActivity).new * getSubCategoryObjects().execute(url2); } */ // Implement On Item click listener gridViewSubCategory .setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) { // TODO Auto-generated method stub BaseActivity.cd = new ConnectionDetector( getActivity()); BaseActivity.isInternetPresent = BaseActivity.cd .isConnectingToInternet(); if (BaseActivity.isInternetPresent) { Intent i = new Intent(getActivity(), SubCategoryActivity.class); i.putExtra("id", ((TextView) view .findViewById(R.id.textViewId)) .getText().toString()); i.putExtra( "color", i.getIntExtra("color", Color.parseColor("#FF666666"))); startActivity(i); } else { Toast.makeText( getActivity(), "به اینترنت متصل نیستید، به اینترنت متصل شده و دوباره امتحان کنید.", Toast.LENGTH_SHORT).show(); } } }); } } public class GridviewAdapter extends BaseAdapter { private Activity activity; private ArrayList&lt;HashMap&lt;String, String&gt;&gt; list; HashMap&lt;String, String&gt; tempMap; public GridviewAdapter(Activity activity, ArrayList&lt;HashMap&lt;String, String&gt;&gt; list) { this.activity = activity; this.list = list; } @Override public int getCount() { // TODO Auto-generated method stub return list.size(); } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub LayoutInflater inflator = activity.getLayoutInflater(); View vi = convertView; if (convertView == null) vi = inflator.inflate(R.layout.gridview_sub_category_row, null); TextView id = (TextView) vi.findViewById(R.id.textViewId); TextView title = (TextView) vi.findViewById(R.id.textViewTitle); ImageView imageViewSubCat = (ImageView) vi .findViewById(R.id.imageViewSubCat); TextView price = (TextView) vi.findViewById(R.id.textViewPrice); TextView date = (TextView) vi.findViewById(R.id.textViewDate); RelativeLayout textBackground = (RelativeLayout) vi .findViewById(R.id.relativeLayoutText); tempMap = new HashMap&lt;String, String&gt;(); tempMap = list.get(position); id.setText(tempMap.get("id")); textBackground.setBackgroundColor(intent.getIntExtra("color", Color.parseColor("#FF666666"))); title.setText(tempMap.get("title")); price.setText(tempMap.get("price")); date.setText(tempMap.get("date")); title.setTypeface(BaseActivity.font); price.setTypeface(BaseActivity.font); date.setTypeface(BaseActivity.font); // File cachedImg = ImageLoader.getInstance().getDiscCache() // .get(picUrl + tempMap.get("logo") + ".jpg"); // if (cachedImg.exists()) // cachedImg.delete(); ImageLoader.getInstance().displayImage( BaseActivity.picUrl + tempMap.get("image") + ".jpg", imageViewSubCat); return vi; } } @Override public boolean onPrepareOptionsMenu(Menu menu) { // TODO Auto-generated method stub menu.clear(); menu.add("آگهی جدید").setIcon(R.drawable.action_advertise_new) .setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS); menu.add("غربال").setIcon(R.drawable.action_search) .setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS); menu.add("مرتب سازی").setIcon(R.drawable.action_sort) .setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS); return super.onPrepareOptionsMenu(menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == android.R.id.home) { finish(); return true; } return super.onOptionsItemSelected(item); } } </code></pre> <p>code for <strong>activity_list.xml</strong>:</p> <pre><code> &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" &gt; &lt;com.astuetz.viewpager.extensions.PagerSlidingTabStrip android:id="@+id/tabs" android:layout_width="match_parent" android:layout_height="48dip" android:background="@drawable/background_tabs" /&gt; &lt;android.support.v4.view.ViewPager android:id="@+id/pager" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@+id/tabs" tools:context=".SubCategoryActivity" /&gt; &lt;/RelativeLayout&gt; </code></pre> <p>code for <strong>gridview_sub_category_row.xml</strong>:</p> <pre><code> &lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="5dp" &gt; &lt;RelativeLayout android:layout_width="match_parent" android:layout_height="200dp" &gt; &lt;TextView android:id="@+id/textViewId" android:layout_width="wrap_content" android:layout_height="wrap_content" android:visibility="gone" /&gt; &lt;ImageView android:id="@+id/imageViewSubCat" android:layout_width="match_parent" android:layout_height="140dp" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" /&gt; &lt;RelativeLayout android:id="@+id/relativeLayoutText" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@+id/imageViewSubCat" android:background="#FF3F9FE0" &gt; &lt;TextView android:id="@+id/textViewTitle" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_marginLeft="10dp" android:layout_marginRight="10dp" android:layout_marginTop="5dp" android:gravity="right" android:text="همه" android:textAppearance="?android:attr/textAppearanceMedium" /&gt; &lt;TextView android:id="@+id/textViewPrice" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_alignRight="@+id/textViewTitle" android:layout_marginBottom="5dp" android:layout_toRightOf="@+id/textViewDate" android:gravity="right" android:text="20500000 تومان" /&gt; &lt;TextView android:id="@+id/textViewDate" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBaseline="@+id/textViewPrice" android:layout_alignBottom="@+id/textViewPrice" android:layout_alignParentLeft="true" android:layout_marginLeft="14dp" android:text="دقایقی پیش" /&gt; &lt;/RelativeLayout&gt; &lt;/RelativeLayout&gt; &lt;/RelativeLayout&gt; </code></pre> <p>code for <strong>fragment_sub_category_objects.xml</strong>:</p> <pre><code> &lt;FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" &gt; &lt;GridView android:id="@+id/gridViewSubCategory" android:layout_width="match_parent" android:layout_height="match_parent" android:columnWidth="300dp" android:horizontalSpacing="16dp" android:numColumns="auto_fit" android:scrollbars="none" android:verticalSpacing="16dp" &gt; &lt;/GridView&gt; &lt;/FrameLayout&gt; </code></pre>
 

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