Replacing Fragment inside view pager null pointer exception

Replacing Fragment inside view pager null pointer exception - android

My objective is to replace the Fragment inside viewpager. I got a matching solution for the same Replace one fragment with other
Below is the code i am using almost same from the above link
public interface SecondPageFragmentListener {
void onSwitchToNextFragment();
}
I have implemented the above interface in my ViewPager Adapter.I am just pasting my full Code for the Adapter so it easy to understand it for everyone
public class TabPagerAdapter extends FragmentPagerAdapter{
private final Resources resources;
private Context mContext;
SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
Fragment result = null;
FirstPageListener listener = new FirstPageListener();
public TabPagerAdapter(final Resources resources, FragmentManager fm,Context mContext) {
super(fm);
this.mContext = mContext;
this.resources = resources;
}
public void updateData(){
notifyDataSetChanged();
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
// First Fragment of First Tab
result = new Position();
break;
case 1:
// First Fragment of Second Tab
result = new Alerts();
break;
case 2:
// First Fragment of Third Tab
result = new Reports();
break;
default:
result = null;
break;
}
return result;
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(final int position) {
switch (position) {
case 0:
return resources.getString(R.string.tab_position_title);
case 1:
return resources.getString(R.string.tab_alert_title);
case 2:
return resources.getString(R.string.tab_reports_title);
default:
return null;
}
}
#Override
public int getItemPosition(Object object)
{
if (object instanceof Alerts &&
result instanceof CaptureIncident) {
return POSITION_NONE;
}
if (object instanceof CaptureIncident &&
result instanceof Alerts) {
return POSITION_NONE;
}
return POSITION_UNCHANGED;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
public Fragment getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
private final class FirstPageListener implements
SecondPageFragmentListener {
public void onSwitchToNextFragment() {
((AppCompatActivity)mContext).getSupportFragmentManager().beginTransaction().remove(result)
.commit();
if (result instanceof Alerts){
result = CaptureIncident.newInstance("","",listener);
}else{ // Instance of NextFragment
result = Alerts.newInstance("","",listener);
}
notifyDataSetChanged();
}
}
}
I have just created a Inner class and implemented my SecondPageFragmentListener interface as mentioned in the link.
Now I have init the interface in my Alert Fragment
static SecondPageFragmentListener secondPageListener;
public static Alerts newInstance(String param1, String param2,SecondPageFragmentListener listener) {
Alerts fragment = new Alerts();
secondPageListener = listener;
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
Now I am calling the interface method on button click
secondPageListener.onSwitchToNextFragment();
Below is My Fragment Code
public class Alerts extends RootFragment{
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private String mParam1;
private String mParam2;
private RecyclerView gridview;
private GridAdapter gridAdapter;
private GridLayoutManager gridLayoutManager;
private OnFragmentInteractionListener mListener;
public static SecondPageFragmentListener secondPageListener;
public Alerts() {
// Required empty public constructor
}
#SuppressLint("ValidFragment")
public Alerts(SecondPageFragmentListener listener){
secondPageListener = listener;
}
public static Alerts newInstance(String param1, String param2,SecondPageFragmentListener listener) {
Alerts fragment = new Alerts();
secondPageListener = listener;
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_alerts, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
initUiView();
RecyclerListener();
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
private void initUiView() {
gridview = (RecyclerView)getActivity().findViewById(R.id.gridview);
gridview.setHasFixedSize(true);
gridview.setLayoutManager(new GridLayoutManager(getActivity(), 3));
//list Population
List<ItemObject> rowListItem = getAllItemList();
gridAdapter = new GridAdapter(getActivity(),rowListItem);
gridview.setAdapter(gridAdapter);
gridAdapter.notifyDataSetChanged();
}
private List<ItemObject> getAllItemList(){
List<ItemObject> allItems = new ArrayList<ItemObject>();
allItems.add(new ItemObject("altercation","0,50 miles - 10 min ago", R.drawable.altercation));
allItems.add(new ItemObject("offence","0,25 miles - 45 min ago", R.drawable.offence));
allItems.add(new ItemObject("harassment","0,60 miles - 1h ago", R.drawable.harassment));
allItems.add(new ItemObject("doubt","0,5 miles - 48 min ago", R.drawable.doubt));
allItems.add(new ItemObject("incident","0,50 miles - 30 min ago", R.drawable.incident));
return allItems;
}
private void RecyclerListener(){
gridview.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), gridview, new ItemClickListener(){
#Override
public void onClick(View view, int position) {
Alerts.secondPageListener.onSwitchToNextFragment();
}
#Override
public void onLongClick(View view, int position) {
}
}));
}
}
But it showing me the error
java.lang.NullPointerException
at
com.oxilo.mrsafer.fragement.Alerts$1.onClick(Alerts.java:173)
The error indicates that secondpagelitener is null.
Please help me to resolve the issue.
Also on the below link
Replace one fragment with other
he implement the same interface in Fragment too as he already implemented
the interface in view pager adapter. so why he is implementing in the Fragment too.From my understanding it wrong but please correct me if i am wrong.

you can try this. for tab2 fragment create xml file like this:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/main"> <!-- this line is the most important part-->
<!-- your other layout s or views go here-->
</FrameLayout>
or just set id to your topest layout in you frag xml and and use it as container id in java code.
then in your fragment code in where you try to call interface to switch fragment just do that:
getChildFragmentManager().beginTransaction().replace(R.id.main, destfragment).addToBackStack("youtag").commit();

You are calling this code
public void onSwitchToNextFragment() {
((AppCompatActivity)mContext).getSupportFragmentManager().beginTransaction().remove(result).commit();
if (result instanceof Alerts){
result = CaptureIncident.newInstance("","",listener);
} else{ // Instance of NextFragment
result = Alerts.newInstance("","",listener);
}
notifyDataSetChanged();
}
From object created here:
case 1:
// First Fragment of Second Tab
result = new Alerts();
break;
so secondPageListener is not initialized yet. You can try to create change your code to this:
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
// First Fragment of First Tab
result = new Position();
break;
case 1:
// First Fragment of Second Tab
result = Alerts.newInstance("","",listener); // This line is important
break;
case 2:
// First Fragment of Third Tab
result = new Reports();
break;
default:
result = null;
break;
}
return result;
}
EDIT
If it's going to be static then you can try this:
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
// First Fragment of First Tab
result = new Position();
break;
case 1:
// First Fragment of Second Tab
result = Alerts.newInstance("","",listener); // This line is important
Alerts.secondPageListener = listener;
break;
case 2:
// First Fragment of Third Tab
result = new Reports();
break;
default:
result = null;
break;
}
return result;
}
Also make sure to call it like this in your onClick
Alerts.secondPageListener.onSwitchToNextFragment();

Related

Access Id from parent activity to fragments in ViewPager

I have faced this issue, maybe there is already the same issue, but I cannot find in this page. So my problem is that I have my activity, which initialize ViewPager and I have 2 fragments in this viewpager.
My Activity:
public class ShoppingDetailsActivity extends BaseActivity {
ViewPagerAdapter adapter;
#Bind(R.id.view_pager)
ViewPager viewPager;
#Bind(R.id.pager_tabs)
PagerSlidingTabStrip pagerSlidingTabStrip;
int shop_id;
int id;
int shop_sub_id;
int subId;
int shop_sub_sub_id;
int subSubId;
int shop_detail_id;
int detailId;
public static final String SHOP_ID = "shop_id";
public static final String SHOP_SUB_ID = "shop_sub_id";
public static final String SHOP_SUB_SUB_ID = "shop_sub_sub_id";
public static final String SHOP_DETAIL_ID = "shop_detail_id";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityComponent().inject(this);
setContentView(R.layout.activity_shopping_details);
ButterKnife.bind(this);
adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
pagerSlidingTabStrip.setViewPager(viewPager);
shop_id = getIntent().getIntExtra(SHOP_ID, id);
shop_sub_id = getIntent().getIntExtra(SHOP_SUB_ID, subId);
shop_sub_sub_id = getIntent().getIntExtra(SHOP_SUB_SUB_ID, subSubId);
shop_detail_id = getIntent().getIntExtra(SHOP_DETAIL_ID, detailId);
}
}
My Adapter:
public class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new InfoAdminFragment();
break;
case 1:
fragment = new ViewAdminFragment();
break;
default:
break;
}
return fragment;
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return "InfoAdminFragment";
} else if (position == 1) {
return "ViewAdminFragment";
} else {
return super.getPageTitle(position);
}
}
}
As you can see in My Activity I have a lot of IDs using getIntent() and get them successfully, but I also need somehow to pass to my both fragments in ViewPager, how can I make solve this issue?

Pass the ID's as bundle to ViewPager adapter from your activity
adapter = new ViewPagerAdapter(getSupportFragmentManager(), getIntent().getExtras());
Modify your ViewPager adapter as below
public class ViewPagerAdapter extends FragmentPagerAdapter {
private Bundle bundle;
public ViewPagerAdapter(FragmentManager fm, Bundle bundle) {
super(fm);
this.bundle = bundle;
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new InfoAdminFragment();
break;
case 1:
fragment = new ViewAdminFragment();
break;
default:
fragment = new InfoAdminFragment();
break;
}
fragment.setArguments(bundle);
return fragment;
}
//other code
}
And retrieve the bundle in your fragments
Bundle bundle = getArguments();
shopId = bundle.getInt(ShoppingDetailsActivity.SHOP_ID);

Check your code with this one:
private int shop_id;
private int shop_sub_id;
private int shop_sub_sub_id;
private int shop_detail_id;
public void setExtraData(int shopId, int shopSubId, shopSubSubId, shopDetailId) {
this.shop_id = shopId;
this.shop_sub_id = shopSubId;
this.shop_sub_sub_id = shopSubSubId;
this.shop_detail_id = shopDetailId;
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new InfoAdminFragment();
break;
case 1:
fragment = new ViewAdminFragment();
break;
default:
break;
}
setBundleData(fragment);
return fragment;
}
public void setBundleData(Fragment fragment){
Bundle bundle = new Bundle();
bundle.putInt("shop_id", shop_id);
bundle.putInt("shop_sub_id", shop_sub_id);
bundle.putInt("shop_sub_sub_id", shop_sub_sub_id);
bundle.putInt("shop_detail_id", shop_detail_id);
fragment.setArguments(bundle);
}
And in your activity:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityComponent().inject(this);
setContentView(R.layout.activity_shopping_details);
ButterKnife.bind(this);
shop_id = getIntent().getIntExtra(SHOP_ID, id);
shop_sub_id = getIntent().getIntExtra(SHOP_SUB_ID, subId);
shop_sub_sub_id = getIntent().getIntExtra(SHOP_SUB_SUB_ID, subSubId);
shop_detail_id = getIntent().getIntExtra(SHOP_DETAIL_ID, detailId);
adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.setExtraData(shop_id, shop_sub_id, shop_sub_sub_id, shop_detail_id);
viewPager.setAdapter(adapter);
pagerSlidingTabStrip.setViewPager(viewPager);
}
In your fragment you can get:
getArguments().getInt(/*Key*/, /*Default value*/);
like:
getArguments().getInt("shop_id", -1);
You can achieve the same above scenario by passing intent rather than single-single values as I am doing here in setExtraData method of adapter.

Viewpager does not inflate the fragments having already inflated another view pager

I have a project that needs to have two viewpager, each in a different fragment of the activity.
The architecture something like this
The problem is that when a pager view is inflated, the other isn't.
For example, the fragments 1, 2 and 3 can be accessed by clicking. When I click on the first fragment, it inflates the view pager with its two fragments perfectly, but if I click on the fragment 3, the view pager does not inflate the fragments and also the tabs get slower.
Opening the application process again, by clicking on the fragment 3 first, it works perfectly, but clicking on the first after, this problem happens again.
Already debugged the processes and there is nothing different.
My Activity
public class HomeActivity extends AppCompatActivity implements NavigationFragment.OnNavigationListener{
public NavigationFragment mNavigation;
private String mTagFragmentShowing = "";
private int currentNavigation = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
ButterKnife.bind(this);
mNavigation = (NavigationFragment) getFragmentManager().findFragmentById(R.id.manager_navigation);
onNavigationSelected(currentNavigation);
}
#Override
public void onNavigationSelected(int position) {
if (mTagFragmentShowing.equals(String.valueOf(position)))
return;
currentNavigation = position;
mNavigation.setNavigationSelected(position);
FragmentManager fragmentManager = getSupportFragmentManager();
Fragment fragment = fragmentManager.findFragmentByTag(mTagFragmentShowing);
// Hide last fragment
if (fragment != null && fragment.isVisible()) {
fragmentManager.beginTransaction().hide(fragment).commit();
}
// Show new fragment
mTagFragmentShowing = String.valueOf(position);
fragment = fragmentManager.findFragmentByTag(mTagFragmentShowing);
if (fragment != null && fragment.isHidden()) {
fragmentManager.beginTransaction().show(fragment).commit();
} else if (fragment == null) {
fragmentManager.beginTransaction().add(R.id.manager_content, getFragmentByPosition(position), mTagFragmentShowing)
.setTransition(FragmentTransaction.TRANSIT_NONE).commit();
}
}
private Fragment getFragmentByPosition(int position) {
switch (position) {
case 0:
return new DiscoverFragment();
case 1:
return new UpcomingFragment();
case 2:
return new FeaturesFragment();
case 3:
return new VideosFragment();
case 4:
return new MySongsFragment();
}
return null;
}
My Navigation Fragment. It control the other fragments
public class NavigationFragment extends Fragment implements View.OnClickListener {
public ViewHolder mHolder;
public View mButtonSelected;
public OnNavigationListener mCallback;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.component_navigation, container, false);
ButterKnife.bind(this, view);
initView(view);
return view;
}
public void initView(View view) {
mHolder = new ViewHolder();
mHolder.discover = view.findViewById(R.id.component_navigation_discover);
mHolder.upcoming = view.findViewById(R.id.component_navigation_upcoming);
mHolder.features = view.findViewById(R.id.component_navigation_features);
mHolder.videos = view.findViewById(R.id.component_navigation_videos);
mHolder.mymusic = view.findViewById(R.id.component_navigation_mymusic);
mHolder.discover.setTag(0);
mHolder.upcoming.setTag(1);
mHolder.features.setTag(2);
mHolder.videos.setTag(3);
mHolder.mymusic.setTag(4);
mHolder.discover.setOnClickListener(this);
mHolder.upcoming.setOnClickListener(this);
mHolder.features.setOnClickListener(this);
mHolder.videos.setOnClickListener(this);
mHolder.mymusic.setOnClickListener(this);
mButtonSelected = mHolder.features;
}
public void setNavigationSelected(int position) {
setNavigationButtonSelected(false);
switch (position) {
case 0:
mButtonSelected = mHolder.discover;
break;
case 1:
mButtonSelected = mHolder.upcoming;
break;
case 2:
mButtonSelected = mHolder.features;
break;
case 3:
mButtonSelected = mHolder.videos;
break;
case 4:
mButtonSelected = mHolder.mymusic;
break;
}
setNavigationButtonSelected(true);
}
public void setNavigationButtonSelected(boolean enabled) {
mButtonSelected.setBackgroundColor(enabled ? getResources().getColor(R.color.color_red) : Color.TRANSPARENT);
}
#Override
public void onClick(View view) {
if (view != mButtonSelected) {
mCallback.onNavigationSelected((Integer) view.getTag());
}
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mCallback = (OnNavigationListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnNavigationSelectedListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mCallback = null;
}
static class ViewHolder {
View discover;
View upcoming;
View features;
View videos;
View mymusic;
}
public interface OnNavigationListener {
public void onNavigationSelected(int position);
}
My Fragments with View Pager
public class MySongsFragment extends Fragment {
private OnFragmentInteractionListener mListener;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
getActivity().getSupportFragmentManager().beginTransaction().add(R.id.mysongs_fragment_container, MySongsViewPagerFragment.newInstance(0)).commit();
return inflater.inflate(R.layout.fragment_my_songs, container, false);
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
My View Pager
public class MySongsViewPagerFragment extends Fragment {
private static final int NUM_PAGES = 4;
private String[] tab_names;
private List<String> mTabNames;
private PagerAdapter mPagerAdapter;
public #Bind(R.id.pager)
ViewPager mPager;
public static MySongsViewPagerFragment newInstance(int index) {
MySongsViewPagerFragment fragment = new MySongsViewPagerFragment();
Bundle args = new Bundle();
args.putInt("index", index);
fragment.setArguments(args);
return fragment;
}
#Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = initView(inflater, container);
return view;
}
#NonNull private View initView(LayoutInflater inflater, ViewGroup container) {
View view = inflater.inflate(R.layout.fragment_view_pager_my_songs, container, false);
ButterKnife.bind(this, view);
tab_names = getResources().getStringArray(R.array.tabs_mysongs);
mTabNames = Arrays.asList(tab_names);
mPagerAdapter = new ScreenSlidePagerAdapter(getActivity().getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
mPager.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
mPager.onTouchEvent(event);
return false;
}
});
TabLayout tabLayout = (TabLayout) view.findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mPager);
return view;
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override public Fragment getItem(int position) {
switch (position) {
case 0:
return new PlaylistsFragment();
case 1:
return new SongsFragment();
case 2:
return new AlbumsFragment();
case 3:
return new ArtistsFragment();
default:
return new PlaylistsFragment();
}
}
#Override public int getCount() {
return NUM_PAGES;
}
#Override public CharSequence getPageTitle(int position) {
return mTabNames.get(position);
}
}

The problem was activity context in viewpager
In My View Pagers. I change
mPagerAdapter = new ScreenSlidePagerAdapter(getActivity().getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
to
mPagerAdapter = new ScreenSlidePagerAdapter(getChildFragmentManager());
mPager.setAdapter(mPagerAdapter);
The two viewpager used the same context. So when I inflated the first, the other was not inflated because interpreted that already existed an inflated viewpager.
Thanks for the help mcwise for show me the method getChildFragmentManager().

Passing Data into Fragment outside ViewPager and FragmentPagerAdapter

What I want to do is, pass a sorting variable into specific ViewPager's fragment
My ViewPager is work. I used OnPageChangeListener to get the current fragment and current tab position.
But, when I pass the variable outside the Listener, it always changed to 0
code: currentPos = arg0; (arg0 is returning correct position)
System.out.println("Current:" + currentPos);
All Tab Display result: Current:0
ThirdTab.java:
private PagerSlidingTabStrip tabs;
private ViewPager pager;
private MyPagerAdapter adapter;
public Fragment fragment;
public int currentPos;
public String getSorting() {
return sorting;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.third_tab, container, false);
setHasOptionsMenu(true);
tabs = (PagerSlidingTabStrip) rootView.findViewById(R.id.slidingTabStrip);
pager = (ViewPager) rootView.findViewById(R.id.pager);
adapter = new MyPagerAdapter(getChildFragmentManager(), getActivity().getApplicationContext());
adapter.setTitle(catType);
pager.setAdapter(adapter);
final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources()
.getDisplayMetrics());
pager.setPageMargin(pageMargin);
tabs.setViewPager(pager);
pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
System.out.println("Good" + arg0);
fragment = ((MyPagerAdapter) pager.getAdapter()).getFragment(arg0);
currentPos = arg0;
if (arg0 == 1 && fragment != null) {
fragment.onResume();
}
}
#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
}
});
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// handle item selection
switch (item.getItemId()) {
case R.id.menuSortRecentCreate:
case R.id.menuSortRecentUpdate:
case R.id.menuSortLowestPrice:
case R.id.menuSortHighestPrice:
if (item.getItemId() == R.id.menuSortRecentCreate) {
sorting = "0";
} else if (item.getItemId() == R.id.menuSortRecentUpdate) {
sorting = "1";
} else if (item.getItemId() == R.id.menuSortLowestPrice) {
sorting = "2";
} else if (item.getItemId() == R.id.menuSortHighestPrice) {
sorting = "3";
}
System.out.println("Current:" + currentPos);
System.out.println("Current Page:" + pager.getCurrentItem());
return true;
case R.id.action_search:
return true;
case R.id.action_setting:
ThirdTabTaskSettingActivity fragment = new ThirdTabTaskSettingActivity();
mainActivity.pushFragments(getResources().getString(R.string.title_third_tab), fragment, true, true);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
MyPagerAdapter in ThirdTab.java
public class MyPagerAdapter extends FragmentStatePagerAdapter {
private String[] TITLES = {};
private String[] PERSONAL_TITLES = { getString(R.string.personal_category1), getString(R.string.personal_category2), getString(R.string.personal_category3),
getString(R.string.personal_category4), getString(R.string.personal_category5), getString(R.string.personal_category6) };
private String[] BUSINESS_TITLES = { getString(R.string.business_category1), getString(R.string.business_category2), getString(R.string.business_category3),
getString(R.string.business_category4), getString(R.string.business_category5) };
HashMap<Integer, Fragment> hm = new HashMap<Integer, Fragment>();
private Map<Integer, String> mFragmentTags;
private FragmentManager mFragmentManager;
private Context mContext;
public MyPagerAdapter(FragmentManager fm, Context context) {
super(fm);
mFragmentManager = fm;
mFragmentTags = new HashMap<Integer, String>();
mContext = context;
}
public void setTitle(String category) {
if (category.equals("personal")) {
TITLES = PERSONAL_TITLES;
}
else {
TITLES = BUSINESS_TITLES;
}
}
#Override
public CharSequence getPageTitle(int position) {
return TITLES[position];
}
#Override
public int getCount() {
return TITLES.length;
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = ThirdTabContentFragment1.newInstance(position, sorting, keyword);
return fragment;
case 1:
fragment = ThirdTabContentFragment2.newInstance(position, sorting, keyword);
return fragment;
case 2:
fragment = ThirdTabContentFragment3.newInstance(position, sorting, keyword);
return fragment;
case 3:
fragment = ThirdTabContentFragment4.newInstance(position, sorting, keyword);
return fragment;
case 4:
fragment = ThirdTabContentFragment5.newInstance(position, sorting, keyword);
return fragment;
case 5:
fragment = ThirdTabContentFragment6.newInstance(position, sorting, keyword);
return fragment;
}
return fragment;
// return SuperAwesomeCardFragment.newInstance(position, sorting, keyword);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
System.out.println("instantiate");
Object obj = super.instantiateItem(container, position);
if (obj instanceof Fragment) {
Fragment f = (Fragment) obj;
String tag = f.getTag();
mFragmentTags.put(position, tag);
}
return obj;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
public Fragment getFragment(int position) {
System.out.println("In:" + position);
String tag = mFragmentTags.get(position);
if (tag == null) { return null; }
return mFragmentManager.findFragmentByTag(tag);
}
}
ReceiveData's Fragment
public class ThirdTabContentFragment1 extends BaseContainerFragment implements AsyncResponse {
public static ThirdTabContentFragment1 newInstance(int position, String vSorting, String vKeyword) {
ThirdTabContentFragment1 f = new ThirdTabContentFragment1();
Bundle b = new Bundle();
b.putInt(ARG_POSITION, position);
f.setArguments(b);
System.out.println("a" + position);
return f;
}
#Override
public void onResume() {
System.out.println("Resume1");
super.onResume();
}
}

When to update information for ViewPager?

If I ave an activity with a viewPAger on it and two sets of data that I want to display, is it best to have one fragment and load information into textViews based on position passed from activity or better to create more than one fragment and load the one needed?
Any help is greatly appreciated.
public class testFragment extends Fragment {
private static final String ARG_PAGE = "pageNumber";
private static final int DEFAULT_INT = 0;
TextView header, sd1;
int h1, page = 0;
public testFragment (){
}
public testFragment newInstance(int pageNumber) {
testFragment fragment = new testFragment ();
Bundle args = new Bundle();
args.putInt(ARG_PAGE, pageNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
page = getArguments().getInt(ARG_PAGE);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment_high_scores_page, container, false);
return rootView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
header = (TextView) getActivity().findViewById(R.id.modes_header);
sd1 = (TextView) getActivity().findViewById(R.id.stat_det_1);
switch (page) {
case 1:
header.setText(R.string.easy_mode);
h1 = DEFAULT_INT;
sh1 = DEFAULT_INT;
sd1.setText(String.valueOf(h1));
break;
case 2:
header.setText(R.string.medium_mode);
h1 = DEFAULT_INT + 1;
sh1 = DEFAULT_INT + 1;
sd1.setText(String.valueOf(h1));
break;
default:
header.setText(R.string.action_restart);
h1 = DEFAULT_INT;
sh1 = DEFAULT_INT;
sd1.setText(String.valueOf(h1));
break;
}
}
public void setTextViewInfo(){
sd1.setText(String.valueOf(h1));
}
}
Or would it be better to send the information from my activity and load one or multiple fragments instead?
public class testActivity extends FragmentActivity {
private static final int NUM_PAGES = 8;
private ViewPager mPager;
private PagerAdapter mPagerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.testActivity);
// Instantiate a ViewPager and a PagerAdapter.
mPager = (ViewPager) findViewById(R.id.high_scores_pager);
mPagerAdapter = new testActivity (getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
}
#Override
public void onBackPressed() {
if (mPager.getCurrentItem() == 0) {
super.onBackPressed();
} else {
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
}
}
private class testActivityAdapter extends FragmentStatePagerAdapter {
public testActivityAdapter (FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
testFragment tf1 = new testFragment ();
notifyDataSetChanged();
return easy.newInstance(position);
case 1:
testFragment2 tf2 = new testFragment ();
notifyDataSetChanged();
return medium.newInstance(position);
default:
testFragment d = new testFragment ();
return d.newInstance();
}
}
#Override
public int getItemPosition(Object object) {
return super.getItemPosition(object);
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
}
edit:
In my adapter, I just tried
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return HighScoresEasyFragment.newInstance(position);
case 1:
return HighScoresMediumFragment.newInstance(position);
case 2:
return HighScoresExpertFragment.newInstance(position);
case 3:
return HighScoresBrainFartFragment.newInstance(position);
case 4:
return HighScoresClassicFragment.newInstance(position);
case 5:
return HighScoresPuzzleFragment.newInstance(position);
case 6:
return HighScoresPerfectFragment.newInstance(position);
case 7:
return HighScoresPowerFragment.newInstance(position);
default:
return HighScoresEasyFragment.newInstance(position);
}
ugh, but it didn't load anything... my constructor is now...:
public static HighScoresEasyFragment newInstance(int pageNumber) {
HighScoresEasyFragment fragment = new HighScoresEasyFragment();
Bundle args = new Bundle();
args.putInt(ARG_PAGE, pageNumber);
fragment.setArguments(args);
return fragment;
}
It loaded the first page's header but no data and it didn't load anything for second to 8th fragments...

You should call notifyDataChanged() from your activity using your adapter reference. Basically notifyDataChanged just tells all your fragments in your adapter that data has changed and they should refresh themselves. Remove notifyDataChanged from your getItem() method and put it when you change data in your activity.

Remove Fragment Page from ViewPager in Android

I'm trying to dynamically add and remove Fragments from a ViewPager, adding works without any problems, but removing doesn't work as expected.
Everytime I want to remove the current item, the last one gets removed.
I also tried to use an FragmentStatePagerAdapter or return POSITION_NONE in the adapter's getItemPosition method.
What am I doing wrong?
Here's a basic example:
MainActivity.java
public class MainActivity extends FragmentActivity implements TextProvider {
private Button mAdd;
private Button mRemove;
private ViewPager mPager;
private MyPagerAdapter mAdapter;
private ArrayList<String> mEntries = new ArrayList<String>();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mEntries.add("pos 1");
mEntries.add("pos 2");
mEntries.add("pos 3");
mEntries.add("pos 4");
mEntries.add("pos 5");
mAdd = (Button) findViewById(R.id.add);
mRemove = (Button) findViewById(R.id.remove);
mPager = (ViewPager) findViewById(R.id.pager);
mAdd.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
addNewItem();
}
});
mRemove.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
removeCurrentItem();
}
});
mAdapter = new MyPagerAdapter(this.getSupportFragmentManager(), this);
mPager.setAdapter(mAdapter);
}
private void addNewItem() {
mEntries.add("new item");
mAdapter.notifyDataSetChanged();
}
private void removeCurrentItem() {
int position = mPager.getCurrentItem();
mEntries.remove(position);
mAdapter.notifyDataSetChanged();
}
#Override
public String getTextForPosition(int position) {
return mEntries.get(position);
}
#Override
public int getCount() {
return mEntries.size();
}
private class MyPagerAdapter extends FragmentPagerAdapter {
private TextProvider mProvider;
public MyPagerAdapter(FragmentManager fm, TextProvider provider) {
super(fm);
this.mProvider = provider;
}
#Override
public Fragment getItem(int position) {
return MyFragment.newInstance(mProvider.getTextForPosition(position));
}
#Override
public int getCount() {
return mProvider.getCount();
}
}
}
TextProvider.java
public interface TextProvider {
public String getTextForPosition(int position);
public int getCount();
}
MyFragment.java
public class MyFragment extends Fragment {
private String mText;
public static MyFragment newInstance(String text) {
MyFragment f = new MyFragment(text);
return f;
}
public MyFragment() {
}
public MyFragment(String text) {
this.mText = text;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment, container, false);
((TextView) root.findViewById(R.id.position)).setText(mText);
return root;
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="#+id/add"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="add new item" />
<Button
android:id="#+id/remove"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="remove current item" />
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1" />
</LinearLayout>
fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/position"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="35sp" />
</LinearLayout>

The ViewPager doesn't remove your fragments with the code above because it loads several views (or fragments in your case) into memory. In addition to the visible view, it also loads the view to either side of the visible one. This provides the smooth scrolling from view to view that makes the ViewPager so cool.
To achieve the effect you want, you need to do a couple of things.
Change the FragmentPagerAdapter to a FragmentStatePagerAdapter. The reason for this is that the FragmentPagerAdapter will keep all the views that it loads into memory forever. Where the FragmentStatePagerAdapter disposes of views that fall outside the current and traversable views.
Override the adapter method getItemPosition (shown below). When we call mAdapter.notifyDataSetChanged(); the ViewPager interrogates the adapter to determine what has changed in terms of positioning. We use this method to say that everything has changed so reprocess all your view positioning.
And here's the code...
private class MyPagerAdapter extends FragmentStatePagerAdapter {
//... your existing code
#Override
public int getItemPosition(Object object){
return PagerAdapter.POSITION_NONE;
}
}

The solution by Louth was not enough to get things working for me, as the existing fragments were not getting destroyed. Motivated by this answer, I found that the solution is to override the getItemId(int position) method of FragmentPagerAdapter to give a new unique ID whenever there has been a change in the expected position of a Fragment.
Source Code:
private class MyPagerAdapter extends FragmentPagerAdapter {
private TextProvider mProvider;
private long baseId = 0;
public MyPagerAdapter(FragmentManager fm, TextProvider provider) {
super(fm);
this.mProvider = provider;
}
#Override
public Fragment getItem(int position) {
return MyFragment.newInstance(mProvider.getTextForPosition(position));
}
#Override
public int getCount() {
return mProvider.getCount();
}
//this is called when notifyDataSetChanged() is called
#Override
public int getItemPosition(Object object) {
// refresh all fragments when data set changed
return PagerAdapter.POSITION_NONE;
}
#Override
public long getItemId(int position) {
// give an ID different from position when position has been changed
return baseId + position;
}
/**
* Notify that the position of a fragment has been changed.
* Create a new ID for each position to force recreation of the fragment
* #param n number of items which have been changed
*/
public void notifyChangeInPosition(int n) {
// shift the ID returned by getItemId outside the range of all previous fragments
baseId += getCount() + n;
}
}
Now, for example if you delete a single tab or make some change to the order, you should call notifyChangeInPosition(1) before calling notifyDataSetChanged(), which will ensure that all the Fragments will be recreated.
Why this solution works
Overriding getItemPosition():
When notifyDataSetChanged() is called, the adapter calls the notifyChanged() method of the ViewPager which it is attached to. The ViewPager then checks the value returned by the adapter's getItemPosition() for each item, removing those items which return POSITION_NONE (see the source code) and then repopulating.
Overriding getItemId():
This is necessary to prevent the adapter from reloading the old fragment when the ViewPager is repopulating. You can easily understand why this works by looking at the source code for instantiateItem() in FragmentPagerAdapter.
final long itemId = getItemId(position);
// Do we already have this fragment?
String name = makeFragmentName(container.getId(), itemId);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
mCurTransaction.attach(fragment);
} else {
fragment = getItem(position);
if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
mCurTransaction.add(container.getId(), fragment,
makeFragmentName(container.getId(), itemId));
}
As you can see, the getItem() method is only called if the fragment manager finds no existing fragments with the same Id. To me it seems like a bug that the old fragments are still attached even after notifyDataSetChanged() is called, but the documentation for ViewPager does clearly state that:
Note this class is currently under early design and development. The API will likely change in later updates of the compatibility library, requiring changes to the source code of apps when they are compiled against the newer version.
So hopefully the workaround given here will not be necessary in a future version of the support library.

my working solution to remove fragment page from view pager
public class MyFragmentAdapter extends FragmentStatePagerAdapter {
private ArrayList<ItemFragment> pages;
public MyFragmentAdapter(FragmentManager fragmentManager, ArrayList<ItemFragment> pages) {
super(fragmentManager);
this.pages = pages;
}
#Override
public Fragment getItem(int index) {
return pages.get(index);
}
#Override
public int getCount() {
return pages.size();
}
#Override
public int getItemPosition(Object object) {
int index = pages.indexOf (object);
if (index == -1)
return POSITION_NONE;
else
return index;
}
}
And when i need to remove some page by index i do this
pages.remove(position); // ArrayList<ItemFragment>
adapter.notifyDataSetChanged(); // MyFragmentAdapter
Here it is my adapter initialization
MyFragmentAdapter adapter = new MyFragmentAdapter(getSupportFragmentManager(), pages);
viewPager.setAdapter(adapter);

The fragment must be already removed but the issue was viewpager save state
Try
myViewPager.setSaveFromParentEnabled(false);
Nothing worked but this solved the issue !
Cheers !

I had the idea of simply copy the source code from android.support.v4.app.FragmentPagerAdpater into a custom class named
CustumFragmentPagerAdapter. This gave me the chance to modify the instantiateItem(...) so that every time it is called, it removes / destroys the currently attached fragment before it adds the new fragment received from getItem() method.
Simply modify the instantiateItem(...) in the following way:
#Override
public Object instantiateItem(ViewGroup container, int position) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
final long itemId = getItemId(position);
// Do we already have this fragment?
String name = makeFragmentName(container.getId(), itemId);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
// remove / destroy current fragment
if (fragment != null) {
mCurTransaction.remove(fragment);
}
// get new fragment and add it
fragment = getItem(position);
mCurTransaction.add(container.getId(), fragment, makeFragmentName(container.getId(), itemId));
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}

You can combine both for better :
private class MyPagerAdapter extends FragmentStatePagerAdapter {
//... your existing code
#Override
public int getItemPosition(Object object){
if(Any_Reason_You_WantTo_Update_Positions) //this includes deleting or adding pages
return PagerAdapter.POSITION_NONE;
}
else
return PagerAdapter.POSITION_UNCHANGED; //this ensures high performance in other operations such as editing list items.
}

I had some problems with FragmentStatePagerAdapter.
After removing an item:
there was another item used for a position (an item which did not belong to the position but to a position next to it)
or some fragment was not loaded (there was only blank background visible on that page)
After lots of experiments, I came up with the following solution.
public class SomeAdapter extends FragmentStatePagerAdapter {
private List<Item> items = new ArrayList<Item>();
private boolean removing;
#Override
public Fragment getItem(int position) {
ItemFragment fragment = new ItemFragment();
Bundle args = new Bundle();
// use items.get(position) to configure fragment
fragment.setArguments(args);
return fragment;
}
#Override
public int getCount() {
return items.size();
}
#Override
public int getItemPosition(Object object) {
if (removing) {
return PagerAdapter.POSITION_NONE;
}
Item item = getItemOfFragment(object);
int index = items.indexOf(item);
if (index == -1) {
return POSITION_NONE;
} else {
return index;
}
}
public void addItem(Item item) {
items.add(item);
notifyDataSetChanged();
}
public void removeItem(int position) {
items.remove(position);
removing = true;
notifyDataSetChanged();
removing = false;
}
}
This solution only uses a hack in case of removing an item. Otherwise (e.g. when adding an item) it retains the cleanliness and performance of an original code.
Of course, from the outside of the adapter, you call only addItem/removeItem, no need to call notifyDataSetChanged().

For future readers!
Now you can use ViewPager2 for dynamically adding, removing fragment from the viewpager.
Quoting form API reference
ViewPager2 replaces ViewPager, addressing most of its predecessor’s
pain-points, including right-to-left layout support, vertical
orientation, modifiable Fragment collections, etc.
Take look at MutableCollectionFragmentActivity.kt in googlesample/android-viewpager2 for an example of adding, removing fragments dynamically from the viewpager.
For your information:
Articles:
Exploring the ViewPager2
Look deep into ViewPager2
API reference
Release notes
Samples Repo: https://github.com/googlesamples/android-viewpager2

Louth's answer works fine. But I don't think always return POSITION_NONE is a good idea. Because POSITION_NONE means that fragment should be destroyed and a new fragment will be created.
You can check that in dataSetChanged function in the source code of ViewPager.
if (newPos == PagerAdapter.POSITION_NONE) {
mItems.remove(i);
i--;
... not related code
mAdapter.destroyItem(this, ii.position, ii.object);
So I think you'd better use an arraylist of weakReference to save all the fragments you have created. And when you add or remove some page, you can get the right position from your own arraylist.
public int getItemPosition(Object object) {
for (int i = 0; i < mFragmentsReferences.size(); i ++) {
WeakReference<Fragment> reference = mFragmentsReferences.get(i);
if (reference != null && reference.get() != null) {
Fragment fragment = reference.get();
if (fragment == object) {
return i;
}
}
}
return POSITION_NONE;
}
According to the comments, getItemPosition is Called when the host view is attempting to determine if an item's position has changed. And the return value means its new position.
But this is not enought. We still have an important step to take.
In the source code of FragmentStatePagerAdapter, there is an array named "mFragments" caches the fragments which are not destroyed. And in instantiateItem function.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
return f;
}
}
It returned the cached fragment directly when it find that cached fragment is not null. So there is a problem. From example, let's delete one page at position 2, Firstly, We remove that fragment from our own reference arraylist. so in getItemPosition it will return POSITION_NONE for that fragment, and then that fragment will be destroyed and removed from "mFragments".
mFragments.set(position, null);
Now the fragment at position 3 will be at position 2. And instantiatedItem with param position 3 will be called. At this time, the third item in "mFramgents" is not null, so it will return directly. But actually what it returned is the fragment at position 2. So when we turn into page 3, we will find an empty page there.
To work around this problem. My advise is that you can copy the source code of FragmentStatePagerAdapter into your own project, and when you do add or remove operations, you should add and remove elements in the "mFragments" arraylist.
Things will be simpler if you just use PagerAdapter instead of FragmentStatePagerAdapter. Good Luck.

add or remove fragment in viewpager dynamically.
Call setupViewPager(viewPager) on activity start.
To load different fragment call setupViewPagerCustom(viewPager).
e.g. on button click call: setupViewPagerCustom(viewPager);
private void setupViewPager(ViewPager viewPager)
{
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new fragmnet1(), "HOME");
adapter.addFrag(new fragmnet2(), "SERVICES");
viewPager.setAdapter(adapter);
}
private void setupViewPagerCustom(ViewPager viewPager)
{
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new fragmnet3(), "Contact us");
adapter.addFrag(new fragmnet4(), "ABOUT US");
viewPager.setAdapter(adapter);
}
//Viewpageradapter, handles the views
static class ViewPagerAdapter extends FragmentStatePagerAdapter
{
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();
}
#Override
public int getItemPosition(Object object){
return PagerAdapter.POSITION_NONE;
}
public void addFrag(Fragment fragment, String title){
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position){
return mFragmentTitleList.get(position);
}
}

Try this solution. I have used databinding for binding view. You can use common "findViewById()" function.
public class ActCPExpense extends BaseActivity implements View.OnClickListener, {
private static final String TAG = ActCPExpense.class.getSimpleName();
private Context mContext;
private ActCpLossBinding mBinding;
private ViewPagerAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try {
setContentView(R.layout.act_cp_loss);
mBinding = DataBindingUtil.setContentView(this, R.layout.act_cp_loss);
mContext = ActCPExpense.this;
initViewsAct();
} catch (Exception e) {
LogUtils.LOGE(TAG, e);
}
}
private void initViewsAct() {
adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(FragmentCPPayee.newInstance(), "Title");
mBinding.viewpager.setAdapter(adapter);
mBinding.tab.setViewPager(mBinding.viewpager);
}
#Override
public boolean onOptionsItemSelected(MenuItem itemActUtility) {
int i = itemActUtility.getItemId();
if (i == android.R.id.home) {
onBackPressed();
}
return super.onOptionsItemSelected(itemActUtility);
}
#Override
public void onClick(View view) {
super.onClick(view);
int id = view.getId();
if (id == R.id.btnAdd) {
addFragment();
} else if (id == R.id.btnDelete) {
removeFragment();
}
}
private void addFragment(){
adapter.addFragment(FragmentCPPayee.newInstance("Title");
adapter.notifyDataSetChanged();
mBinding.tab.setViewPager(mBinding.viewpager);
}
private void removeFragment(){
adapter.removeItem(mBinding.viewpager.getCurrentItem());
mBinding.tab.setViewPager(mBinding.viewpager);
}
class ViewPagerAdapter extends FragmentStatePagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public int getItemPosition(#NonNull Object object) {
return PagerAdapter.POSITION_NONE;
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
public void removeItem(int pos) {
destroyItem(null, pos, mFragmentList.get(pos));
mFragmentList.remove(pos);
mFragmentTitleList.remove(pos);
adapter.notifyDataSetChanged();
mBinding.viewpager.setCurrentItem(pos - 1, false);
}
#Override
public CharSequence getPageTitle(int position) {
return "Title " + String.valueOf(position + 1);
}
}
}

I added a function "clearFragments" and I used that function to clear adapter before setting the new fragments. This calls the proper remove actions of Fragments. My pagerAdapter class:
private class ChartPagerAdapter extends FragmentPagerAdapter{
private ArrayList<Fragment> fragmentList;
ChartPagerAdapter(FragmentManager fm){
super(fm);
fragmentList = new ArrayList<>();
}
void setFragments(ArrayList<? extends Fragment> fragments){
fragmentList.addAll(fragments);
}
void clearFragments(){
for(Fragment fragment:fragmentList)
getChildFragmentManager().beginTransaction().remove(fragment).commit();
fragmentList.clear();
}
#Override
public Fragment getItem(int i) {
return fragmentList.get(i);
}
#Override
public int getCount() {
return fragmentList.size();
}
}

i solved this problem by these steps
1- use FragmentPagerAdapter
2- in each fragment create a random id
fragment.id = new Random().nextInt();
3- override getItemPosition in adapter
#Override
public int getItemPosition(#NonNull Object object) {
return PagerAdapter.POSITION_NONE;
}
4-override getItemId in adapter
#Override
public long getItemId(int position) {
return mDatasetFragments.get(position).id;
}
5- now delete code is
adapter.mDatasetFragments.remove(< item to delete position >);
adapter.notifyDataSetChanged();
this worked for me i hope help

My final version code, fixed ALL bugs. It took me 3 days
Updated 2020/07/18:
I had changed a lot of the source code and fix so many bugs, but I don't promise it still work today.
https://github.com/lin1987www/FragmentBuilder/blob/master/commonLibrary/src/main/java/android/support/v4/app/FragmentStatePagerAdapterFix.java
public class FragmentStatePagerAdapterFix extends PagerAdapter {
private static final String TAG = FragmentStatePagerAdapterFix.class.getSimpleName();
private static final boolean DEBUG = false;
private WeakReference<FragmentActivity> wrFragmentActivity;
private WeakReference<Fragment> wrParentFragment;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
protected ArrayList<Fragment> mFragments = new ArrayList<>();
protected ArrayList<FragmentState> mFragmentStates = new ArrayList<>();
protected ArrayList<String> mFragmentTags = new ArrayList<>();
protected ArrayList<String> mFragmentClassNames = new ArrayList<>();
protected ArrayList<Bundle> mFragmentArgs = new ArrayList<>();
private Fragment mCurrentPrimaryItem = null;
private boolean[] mTempPositionChange;
#Override
public int getCount() {
return mFragmentClassNames.size();
}
public FragmentActivity getFragmentActivity() {
return wrFragmentActivity.get();
}
public Fragment getParentFragment() {
return wrParentFragment.get();
}
public FragmentStatePagerAdapterFix(FragmentActivity activity) {
mFragmentManager = activity.getSupportFragmentManager();
wrFragmentActivity = new WeakReference<>(activity);
wrParentFragment = new WeakReference<>(null);
}
public FragmentStatePagerAdapterFix(Fragment fragment) {
mFragmentManager = fragment.getChildFragmentManager();
wrFragmentActivity = new WeakReference<>(fragment.getActivity());
wrParentFragment = new WeakReference<>(fragment);
}
public void add(Class<? extends android.support.v4.app.Fragment> fragClass) {
add(fragClass, null, null);
}
public void add(Class<? extends android.support.v4.app.Fragment> fragClass, Bundle args) {
add(fragClass, args, null);
}
public void add(Class<? extends android.support.v4.app.Fragment> fragClass, String tag) {
add(fragClass, null, tag);
}
public void add(Class<? extends android.support.v4.app.Fragment> fragClass, Bundle args, String tag) {
add(fragClass, args, tag, getCount());
}
public void add(Class<? extends android.support.v4.app.Fragment> fragClass, Bundle args, String tag, int position) {
mFragments.add(position, null);
mFragmentStates.add(position, null);
mFragmentTags.add(position, tag);
mFragmentClassNames.add(position, fragClass.getName());
mFragmentArgs.add(position, args);
mTempPositionChange = new boolean[getCount()];
}
public void remove(int position) {
if (position < getCount()) {
mTempPositionChange = new boolean[getCount()];
for (int i = position; i < mTempPositionChange.length; i++) {
mTempPositionChange[i] = true;
}
mFragments.remove(position);
mFragmentStates.remove(position);
mFragmentTags.remove(position);
mFragmentClassNames.remove(position);
mFragmentArgs.remove(position);
}
}
public void clear(){
mFragments.clear();
mFragmentStates.clear();
mFragmentTags.clear();
mFragmentClassNames.clear();
mFragmentArgs.clear();
}
#Override
public void startUpdate(ViewGroup container) {
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment;
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
fragment = mFragments.get(position);
if (fragment != null) {
return fragment;
}
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
FragmentState fs = mFragmentStates.get(position);
if (fs != null) {
fragment = fs.instantiate(getFragmentActivity(), getParentFragment());
// Fix bug
// http://stackoverflow.com/questions/11381470/classnotfoundexception-when-unmarshalling-android-support-v4-view-viewpagersav
if (fragment.mSavedFragmentState != null) {
fragment.mSavedFragmentState.setClassLoader(fragment.getClass().getClassLoader());
}
}
if (fragment == null) {
fragment = Fragment.instantiate(getFragmentActivity(), mFragmentClassNames.get(position), mFragmentArgs.get(position));
}
if (DEBUG) {
Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
}
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
mFragments.set(position, fragment);
mFragmentStates.set(position, null);
mCurTransaction.add(container.getId(), fragment, mFragmentTags.get(position));
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) {
Log.v(TAG, "Removing item #" + position + ": f=" + object
+ " v=" + ((Fragment) object).getView());
}
if (position < getCount()) {
FragmentState fragmentState = new FragmentState(fragment);
Fragment.SavedState savedState = mFragmentManager.saveFragmentInstanceState(fragment);
if (savedState != null) {
fragmentState.mSavedFragmentState = savedState.mState;
}
mFragmentStates.set(position, fragmentState);
mFragments.set(position, null);
}
mCurTransaction.remove(fragment);
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
// Fix: Fragment is added by transaction. BUT didn't add to FragmentManager's mActive.
for (Fragment fragment : mFragments) {
if (fragment != null) {
fixActiveFragment(mFragmentManager, fragment);
}
}
}
}
#Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle state = null;
// 目前顯示的 Fragments
for (int i = 0; i < mFragments.size(); i++) {
Fragment f = mFragments.get(i);
if (f != null && f.isAdded()) {
if (state == null) {
state = new Bundle();
}
String key = "f" + i;
mFragmentManager.putFragment(state, key, f);
}
}
if (mFragmentStates.size() > 0) {
if (state == null) {
state = new Bundle();
}
FragmentState[] fs = new FragmentState[mFragmentStates.size()];
mFragmentStates.toArray(fs);
state.putParcelableArray("states_fragment", fs);
}
return state;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state != null) {
Bundle bundle = (Bundle) state;
bundle.setClassLoader(loader);
Parcelable[] fs = bundle.getParcelableArray("states_fragment");
mFragments.clear();
mFragmentStates.clear();
mFragmentTags.clear();
mFragmentClassNames.clear();
mFragmentArgs.clear();
if (fs != null) {
for (int i = 0; i < fs.length; i++) {
FragmentState fragmentState = (FragmentState) fs[i];
mFragmentStates.add(fragmentState);
if (fragmentState != null) {
mFragmentArgs.add(fragmentState.mArguments);
mFragmentTags.add(fragmentState.mTag);
mFragmentClassNames.add(fragmentState.mClassName);
} else {
mFragmentArgs.add(null);
mFragmentTags.add(null);
mFragmentClassNames.add(null);
}
mFragments.add(null);
}
}
Iterable<String> keys = bundle.keySet();
for (String key : keys) {
if (key.startsWith("f")) {
int index = Integer.parseInt(key.substring(1));
Fragment f = mFragmentManager.getFragment(bundle, key);
if (f != null) {
f.setMenuVisibility(false);
mFragments.set(index, f);
mFragmentArgs.set(index, f.mArguments);
mFragmentTags.set(index, f.mTag);
mFragmentClassNames.set(index, f.getClass().getName());
} else {
Log.w(TAG, "Bad fragment at key " + key);
}
}
}
// If restore will change
notifyDataSetChanged();
}
}
public static void fixActiveFragment(FragmentManager fragmentManager, Fragment fragment) {
FragmentManagerImpl fm = (FragmentManagerImpl) fragmentManager;
if (fm.mActive != null) {
int index = fragment.mIndex;
Fragment origin = fm.mActive.get(index);
if (origin != null) {
if ((origin.mIndex != fragment.mIndex) || !(origin.equals(fragment))) {
Log.e(TAG,
String.format("fixActiveFragment: Not Equal! Origin: %s %s, Fragment: %s $s",
origin.getClass().getName(), origin.mIndex,
fragment.getClass().getName(), fragment.mIndex
));
}
}
fm.mActive.set(index, fragment);
}
}
// Fix
// http://stackoverflow.com/questions/10396321/remove-fragment-page-from-viewpager-in-android
#Override
public int getItemPosition(Object object) {
int index = mFragments.indexOf(object);
if (index < 0) {
return PagerAdapter.POSITION_NONE;
}
boolean isPositionChange = mTempPositionChange[index];
int result = PagerAdapter.POSITION_UNCHANGED;
if (isPositionChange) {
result = PagerAdapter.POSITION_NONE;
}
return result;
}
}

2020 now.
Simple add this to PageAdapter:
override fun getItemPosition(`object`: Any): Int {
return PagerAdapter.POSITION_NONE
}

You could just override the destroyItem method
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
fragmentManager.beginTransaction().remove((Fragment) object).commitNowAllowingStateLoss();
}

I hope this can help what you want.
private class MyPagerAdapter extends FragmentStatePagerAdapter {
//... your existing code
#Override
public int getItemPosition(Object object){
return PagerAdapter.POSITION_UNCHANGED;
}
}

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