Develop Reference

FragmentStateAdapter removing last tab instead of current ViewPager2

ViewPager2 is removing last tab instead of current tab, same problem was occurring when i was using viewpager.
Also when selected tab is last one it removes last tab correctly
dependency
implementation "androidx.viewpager2:viewpager2:1.0.0"
This is main activity code
MainActivity.java
public class MainActivity extends AppCompatActivity {
TabLayout tabLayout;
ViewPager2 viewPager;
ViewPagerAdapter adapter;
Button btnAddTab,btnRemoveCurrentTab;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = findViewById(R.id.view_pager);
tabLayout = findViewById(R.id.tabs);
btnAddTab=findViewById(R.id.btn_add);
btnRemoveCurrentTab=findViewById(R.id.btn_remove);
adapter=new ViewPagerAdapter(this);
viewPager.setAdapter(adapter);
new TabLayoutMediator(tabLayout, viewPager,
new TabLayoutMediator.TabConfigurationStrategy() {
#Override public void onConfigureTab(#NonNull TabLayout.Tab tab, int position) {
tab.setText("Store " + (position + 1));
}
}).attach();
btnRemoveCurrentTab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
adapter.removeFrag(tabLayout.getSelectedTabPosition());
}
});
btnAddTab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
DynamicFragment fView = new DynamicFragment();
adapter.addFrag(fView,"Store "+(adapter.getmFragmentIdList().contains(adapter.getItemCount()+1)?adapter.getItemCount()+2:adapter.getItemCount()+1),(adapter.getmFragmentIdList().contains(adapter.getItemCount()+1)?adapter.getItemCount()+2:adapter.getItemCount()+1));
}
});
}
}
ViewPagerAdapter
This is FragentStateAdapter
public class ViewPagerAdapter extends FragmentStateAdapter {
private final List<DynamicFragment> mFragmentList = new ArrayList<>();
private final List<Integer> mFragmentIdList = new ArrayList<>();
public ViewPagerAdapter(#NonNull FragmentActivity fragmentActivity) {
super(fragmentActivity);
}
#NonNull #Override public Fragment createFragment(int position) {
return DynamicFragment.newInstance(String.valueOf(position),mFragmentIdList.get(position));
}
public void addFrag(DynamicFragment fragment, String title, int id) {
mFragmentList.add(fragment);
Log.e("fragment id " ,""+id);
Log.e("fragment array " ,title+ mFragmentList.size());
mFragmentIdList.add(id);
notifyDataSetChanged();
}
public void removeFrag(int pos) {
Log.e("deleted frag",mFragmentIdList.get(pos)+" "+pos);
mFragmentList.remove(pos);
mFragmentIdList.remove(pos);
notifyDataSetChanged();
}
public List<Integer> getmFragmentIdList() {
return mFragmentIdList;
}
#Override
public long getItemId(int position) {
return super.getItemId(position);
}
#Override public int getItemCount() {
return mFragmentList.size();
}
}
Fragment
This is my dynamic fragment which i want to add and remove
public class DynamicFragment extends Fragment {
private static final String ARG_SECTION_NUMBER = "section_number";
private static final String ARG_ID = "id";
private String sectionNumber;
int id;
TextView textView;
EditText editText1,editText2;
public DynamicFragment() {
// Required empty public constructor
}
public static DynamicFragment newInstance(String sectionNumber, int id) {
DynamicFragment fragment = new DynamicFragment();
Bundle args = new Bundle();
args.putString(ARG_SECTION_NUMBER, sectionNumber);
args.putInt(ARG_ID, id);
fragment.setArguments(args);
Log.e("StoreDynamic","dynamic new instance");
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView= inflater.inflate(R.layout.fragment_dynamic, container, false);
textView=rootView.findViewById(R.id.textView);
editText1=rootView.findViewById(R.id.et1);
editText2=rootView.findViewById(R.id.et2);
sectionNumber = getArguments().getString(ARG_SECTION_NUMBER);
id=getArguments().getInt(ARG_ID);
editText1.setText(id+" "+sectionNumber);
textView.setText(id+" "+sectionNumber);
return rootView;
}
}

I ran into the same problem and the solution to this question: remove fragment in viewPager2 use FragmentStateAdapter, but still display worked for me. Mostly the part about overriding the getItemId function to return something other than the position to identify the item because the item's position changes when adding and removing fragments.

You need to overwrite the methods getItemId() and containsItemId()
as shown in this post: https://stackoverflow.com/a/57944197/870242
items variable holds your fragment (mFragmentList )
private val pageIds= items.map { it.hashCode().toLong() }
override fun getItemId(position: Int): Long {
return items[position].hashCode().toLong() // make sure notifyDataSetChanged() works
}
override fun containsItem(itemId: Long): Boolean {
return pageIds.contains(itemId)
}

Viewpager displaying the required details only once and not displaying it a second time when coming back from main screen

I am calling ViewPager(Fragment C) from a ListView(Fragment A). But this only works once. If I move back to my list and select another item , it doesnot move into the listview. It just shows a blank layout of fragment c.
Below is the code for Fragment A:
public class FragmentA extends Fragment implements AdapterView.OnItemClickListener{
ListView list;
Communicator communicator;
ArrayList<Book> book_a;
ArrayList<String> book_titles;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.fragment_a,container,false);
savedInstanceState = getArguments();
if (getArguments() != null) {
// savedInstanceState = getArguments();
book_a = (ArrayList<Book>) getArguments().getSerializable("bookarray");
book_titles = getList(book_a);
//Log.d("Frag_a:Title",book_a.get(5).getTitle());
list= (ListView) view.findViewById(R.id.listview);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_1,book_titles);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
}
return view;
}
public ArrayList<String> getList(ArrayList<Book> book2){
ArrayList<String> list_titles = new ArrayList<String>();
int size = book2.size();
for(int i=0;i<size;i++){
Book object;
object = book2.get(i);
list_titles.add(object.title);
}
return list_titles;
}
public void setCommunicator(Communicator communicator)
{
this.communicator = communicator;
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
communicator.respond(position);
}
public interface Communicator{
public void respond(int index);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof Communicator){
communicator = (Communicator) context;
} else {
throw new RuntimeException(context.toString()+"must implement Communicator");
}
}
#Override
public void onDetach() {
super.onDetach();
communicator = null;
}
}
Below is the code for MainActivity:
public class MainActivity extends AppCompatActivity implements FragmentA.Communicator{
FragmentB f2;
ArrayList<Book> b = new ArrayList<Book>();
FragmentManager manager;
static int flag = 0;
static String search="great";
SearchView sv ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sv = (SearchView) findViewById(R.id.searchView);
sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
flag = 1;
search = query;
getBooks();
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
getBooks();
return false;
}
});
getBooks();
/*
manager = getSupportFragmentManager();
f1 = (FragmentA) manager.findFragmentById(R.id.fragment);
f1.setCommunicator(this);*/
}
#Override
public void respond(int index) {
f2 = (FragmentB) manager.findFragmentById(R.id.fragment2);
if(f2!=null && f2.isVisible())
{
f2.changeData(index);
}
else
{
Bundle bundle = new Bundle();
bundle.putInt("index", index);
bundle.putSerializable("bookarray",(ArrayList<Book>)b);
Fragment newFragment = new FragmentC();
newFragment.setArguments(bundle);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment, newFragment);
transaction.addToBackStack(null);
transaction.commit();
}
}
public void afterGetBooks(ArrayList<Book> bks) {
for (Book h : bks) {
b.add(h);
}
manager = getSupportFragmentManager();
Bundle args = new Bundle();
args.putSerializable("bookarray",(ArrayList<Book>)bks);
FragmentA f1 = new FragmentA();
f1.setArguments(args);
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment,f1);
transaction.addToBackStack(null);
transaction.commit();
f1.setCommunicator(this);
}
private void getBooks(){
String url;
if(flag==0){
url = "https://kamorris.com/lab/audlib/booksearch.php/";}
else{
url = "https://kamorris.com/lab/audlib/booksearch.php?search=" + search;
flag=0;
}
//ArrayList<Book> boo;
Retrofit retrofit = new Retrofit.Builder().baseUrl("https://kamorris.com/lab/audlib/booksearch.php/").addConverterFactory(GsonConverterFactory.create()).build();
Book.API api = retrofit.create(Book.API.class);
Call<ArrayList<Book>> call = api.getBooks(url);
call.enqueue(new Callback<ArrayList<Book>>() {
#Override
public void onResponse(Call<ArrayList<Book>> call, Response<ArrayList<Book>> response) {
ArrayList<Book> Books = response.body();
for(Book h: Books){
Log.d("Retro-Title",h.getTitle());
//b.add(h);
}
afterGetBooks(Books);
}
#Override
public void onFailure(Call<ArrayList<Book>> call, Throwable t) {
Toast.makeText(getApplicationContext(),t.getMessage(),Toast.LENGTH_SHORT).show();
}
});
}
Below is the code for Fragment C:
public class FragmentC extends Fragment {
ViewPager vp;
static int list_pos;
FragmentPagerAdapter adapterViewPager;
public static ArrayList<Book> book_c;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_c,container,false);
if(getArguments()!= null){
book_c = (ArrayList<Book>) getArguments().getSerializable("bookarray");
list_pos = getArguments().getInt("index");
}
vp = (ViewPager) view.findViewById(R.id.viewpager);
adapterViewPager = new MyPagerAdapter(getFragmentManager());
vp.setAdapter(adapterViewPager);
return view;
}
public static class MyPagerAdapter extends FragmentPagerAdapter {
private static int NUM_ITEMS = 11;
public MyPagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
// Returns total number of pages
#Override
public int getCount() {
return NUM_ITEMS;
}
// Returns the fragment to display for that page
#Override
public Fragment getItem(int position) {
switch (list_pos) {
case 0: // Fragment # 0 - This will show FirstFragment
list_pos = position;
return FragmentB.newInstance(book_c,0);
case 1: // Fragment # 0 - This will show FirstFragment different title
list_pos = position;
return FragmentB.newInstance(book_c,1);
case 2: // Fragment # 1 - This will show SecondFragment
list_pos = position;
return FragmentB.newInstance(book_c,2);
case 3: list_pos = position;
return FragmentB.newInstance(book_c,3);
case 4:list_pos = position;
return FragmentB.newInstance(book_c,4);
case 5:list_pos = position;
return FragmentB.newInstance(book_c,5);
case 6:list_pos = position;
return FragmentB.newInstance(book_c,6);
case 7:list_pos = position;
return FragmentB.newInstance(book_c,7);
case 8:list_pos = position;
return FragmentB.newInstance(book_c,8);
case 9:list_pos = position;
return FragmentB.newInstance(book_c,9);
default:
return null;
}
}
// Returns the page title for the top indicator
#Override
public CharSequence getPageTitle(int position) {
return "Page " + position;
}
}
}
Also is there a way, where I can start my viewpager from the description of the listitem which I selected.
Also Fragment B is just a text view holder.
I tried to see the control flow with the debugger. But when I try it that way these lines in Fragment C are not working ..
{
book_c = (ArrayList<Book>) getArguments().getSerializable("bookarray");
list_pos = getArguments().getInt("index");
}
vp = (ViewPager) view.findViewById(R.id.viewpager);
adapterViewPager = new MyPagerAdapter(getFragmentManager());
vp.setAdapter(adapterViewPager);

Your fragment has not been destroyed and therefore when it is brought back, onCreateView is not being called. Instead override setUserVisibleHint.
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
// This is true when your fragment is visible, write code to populate view here
} else {
// This is true when your fragment is hidden.
}
}

The solution i found is to change the Fragment Manager
adapterViewPager = new MyPagerAdapter(getFragmentManager());
to
adapterViewPager = new MyPagerAdapter(getChildFragmentManager());

When the fragment changes tabs, the text doesn't change

When the screen updates and changes tabs, the text of the other tabs still have the characteristics of the first.
private int mPage;
public static FeedFrag newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
FeedFrag fragment = new FeedFrag();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPage = getArguments().getInt(ARG_PAGE);
}
// Inflate the fragment layout we defined above for this fragment
// Set the associated text for the title
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.feed_frag, container, false);
TextView first = (TextView) view.findViewById(R.id.Feed);
first.setText("feed");
return view;
}
And this is another tab
public class InStockFrag extends Fragment {
public static final String ARG_PAGE = "ARG_PAGE";
private int mPage;
public static InStockFrag newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
InStockFrag fragment = new InStockFrag();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPage = getArguments().getInt(ARG_PAGE);
}
// Inflate the fragment layout we defined above for this fragment
// Set the associated text for the title
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.in_stock_frag, container, false);
TextView second = (TextView) view.findViewById(R.id.InStock);
second.setText("In Stock");
return view;
}
}
The Main Activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new SimpleFragmentPagerAdapter(getSupportFragmentManager()));
// Give the PagerSlidingTabStrip the ViewPager
PagerSlidingTabStrip tabsStrip = (PagerSlidingTabStrip) findViewById(R.id.tabs);
tabsStrip.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
// This method will be invoked when a new page becomes selected.
#Override
public void onPageSelected(int position) {
// Toast.makeText(getActivity().this, "Selected page positon: " + position, Toast.LENGTH_SHORT).show();
}
// This method will be invoked when the current page is scrolled
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
// Code goes here
}
// Called when the scroll state changes:
// SCROLL_STATE_IDLE, SCROLL_STATE_DRAGGING, SCROLL_STATE_SETTLING
#Override
public void onPageScrollStateChanged(int state) {
// Code goes here
}
});
tabsStrip.setViewPager(viewPager);
}
SimpleFragmentAdapter:
public class SimpleFragmentPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[] { "Feed", "In Stock", "Upcoming" };
public SimpleFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
return FeedFrag.newInstance(position + 1);
}
#Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}
The app returns the text on the 3 tabs as "feed" instead of the other words.

Yes, obviously. It's because you are not calling correctly your fragments inside the getItem method in your SimpleFragmentPagerAdapter: you were always calling the FeedFrag.
Try to change the code of your view pager adapter like this, and inside the getItem method, put the code to call your third fragment, the one that have title "Upcoming":
public class SimpleFragmentPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[] { "Feed", "In Stock", "Upcoming" };
public SimpleFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
if (position==0) {
return FeedFrag.newInstance(position + 1);
} else if (position == 1) {
return InStockFrag.newInstance(position + 1);
} else {
//HERE RETURN SAME METHOD OF UPCOMING FRAGMENT
}
}
#Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}

How to change Tabs of a TabLayout from Navigation Drawer

Currently I'm changing Tabs from NavigationDrawer but it's not a right way and it takes too long to change tabs from NavigationDrawer becuase I'm replacing Main Fragment of Tabs each time and I don't want it. For more
NavigationDrawerAdapter.java
public class NavDrawerListAdapter extends BaseAdapter {
public Context context;
public MainActivity activity;
public MainTabFragment fragment;
int currentSelectedPostion;
LayoutInflater mInflater;
TextView tv_signup;
SharedPreferences share;
boolean cbc = false;
String fis = "", las = "";
int group_id = 0;
private String[] titles;
private int[] images;
private int[] selectedposition;
public NavDrawerListAdapter(Context context, int[] selectedposition, boolean cb, String fis, String las) {
this.context = context;
this.images = images;
this.cbc = cb;
this.fis = fis;
this.las = las;
share = context.getSharedPreferences("sharePref", 0);
group_id = share.getInt("group_id", 0);
this.selectedposition = selectedposition;
mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
}
#Override
public int getCount() {
return 1;
}
#Override
public Object getItem(int position) {
return position;
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = mInflater.inflate(com.cws.advisorymandi.R.layout.drawer_list_item, null);
}
LinearLayout ll_contact_us = (LinearLayout) convertView.findViewById(com.cws.advisorymandi.R.id.contact_item);
RelativeLayout ll_login = (RelativeLayout) convertView.findViewById(com.cws.advisorymandi.R.id.signup_item);
LinearLayout ll_equity = (LinearLayout) convertView.findViewById(com.cws.advisorymandi.R.id.equity_item);
LinearLayout ll_indices = (LinearLayout) convertView.findViewById(com.cws.advisorymandi.R.id.indices_item);
if (cbc) {
tv_signup.setText("Welcome " + fis + " " + las);
tv_logout.setVisibility(View.VISIBLE);
tv_edit.setVisibility(View.VISIBLE);
}
ll_equity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
MainActivity.getInstance().displayView(3, 0, 0);
}
});
ll_indices.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
MainActivity.getInstance().displayView(3, 0, 1);
}
});
});
return convertView;
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
public ListView mDrawerList;
NavDrawerListAdapter adapter;
public static MainActivity getInstance() {
return sMainActivity;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(com.cws.advisorymandi.R.layout.activity_main)
mDrawerList = (ListView) findViewById(com.cws.advisorymandi.R.id.list_slidermenu);
adapter = new NavDrawerListAdapter(getApplicationContext(), selectedposition, cb, firstName, lastName);
mDrawerList.setAdapter(adapter);
}
/**
* Diplaying fragment view for selected nav drawer list item
*/
public int displayView(int position, int position2, int position3) {
// update the main content by replacing fragments
first_position = position;
second_position = position2;
third_position = position3;
fragment = null;
switch (position) {
case 0:
sharedPreferences = getSharedPreferences("sharePref", 0);
cb = sharedPreferences.getBoolean("ConfirmLogin", false);
if (cb) {
} else new Handler().postDelayed(new Runnable() {
#Override
public void run() {
fragment = new LoginActivity();
changeFragments3();
}
}, 150);
mDrawerLayout.closeDrawer(mDrawerList);
break;
case 3:
// fragment = new MainTabFragment();
/* new Handler().postDelayed(new Runnable() {
#Override
public void run() {*/
fragment = new MainTabFragment();
changeFragments();
/*}
}, 150);
mDrawerLayout.closeDrawer(mDrawerList);*/
break;
}
return 0;
}
}
Note: I created each drawer item without using an array or arrayList so onItemClickListener isn't also working in it.

ViewPager get fragment reference

I have activity where I have created a viewpager that contains two fragments. I need to get a reference to the existing fragment or it's view, in the activity to refresh the list from the fragment if necessary. I was looking for a solution for two days, but found nothing on this occasion.
So here is my adapter
public class SearchPagerAdapter extends FragmentStatePagerAdapter {
CharSequence Titles[];
int NumbOfTabs;
public SearchPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
super(fm);
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
#Override
public Fragment getItem(int position) {
if(position == 0)
{
FragmentAyahSearch tab1 = new FragmentAyahSearch();
return tab1;
}
else
{
FragmentSurahList tab2 = new FragmentSurahList();
return tab2;
}
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
#Override
public CharSequence getPageTitle(int position) {
return Titles[position];
}
#Override
public int getCount() {
return NumbOfTabs;
}
}
below, I create a viewpager and adapter in MainActivity
searchAdapter = new SearchPagerAdapter(getSupportFragmentManager(), searchTitles, Numboftabs);
pager.setAdapter(searchAdapter);
tabs.setViewPager(pager);
I hope you will help me, because I'm losing my mind over this.

I would suggest maintain a list like
private List<Fragment> frag = new ArrayList<Fragment>();
then
public class SearchPagerAdapter extends FragmentStatePagerAdapter {
CharSequence Titles[];
int NumbOfTabs;
public SearchPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
super(fm);
this.Titles = mTitles;
this.NumbOfTabs = mNumbOfTabsumb;
}
#Override
public Fragment getItem(int position)
{
Fragment fragment = frag.get(position);
if(fragment == null )
{
if (position == 0)
{
fragment = new FragmentAyahSearch();
}
else
{
fragment = new FragmentSurahList();
}
}
return fragment;
}
#Override
public CharSequence getPageTitle(int position) {
return Titles[position];
}
#Override
public int getCount() {
return frag.size();
}
now if you want the reference of any fragment
just call , frag.get(<position>) will return you desire frgament