Develop Reference

TabLayoutMediator with ViewPager2 is synchronizing wrong on tab selection -Android java

ViewPager2 is scrolling to the wrong page when I am selecting a tab from a far position. Swiping and selecting tab of loaded pages working fine. The error is only happening when the page is not loaded and scrolling animation is active. I have created a large viewpager2 with 100 pages containing Recyclerview.
My Activity
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TabLayout tabLayout = findViewById(R.id.tabLayout);
ViewPager2 viewPager = findViewById(R.id.viewPager2);
viewPager.setAdapter(new viewPagerAdapter(this));
new TabLayoutMediator(tabLayout, viewPager, true, true,
((tab, position) -> tab.setText("Page: " + position))).attach();
}
private class viewPagerAdapter extends FragmentStateAdapter {
public viewPagerAdapter(FragmentActivity fa) {
super(fa);
}
#Override
public Fragment createFragment(int position) {
Fragment fragment = new itemFragment();
Bundle args = new Bundle();
args.putInt(itemFragment.ARG_PARAM1, position);
fragment.setArguments(args);
return fragment;
}
#Override
public int getItemCount() {
return 100;
}
}
}
My Fragment
public class itemFragment extends Fragment {
public static final String ARG_PARAM1 = "parram1";
int pagePosition;
public itemFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
pagePosition = getArguments().getInt(ARG_PARAM1);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.frgment_item, container, false);
return view;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
TextView textView = view.findViewById(R.id.textView);
textView.setText("Page - " + pagePosition);
RecyclerView recyclerView = view.findViewById(R.id.recyclerView);
recyclerView.setAdapter(new myAdapter());
recyclerView.setLayoutManager(new GridLayoutManager(getContext(), 16));
}
private class myAdapter extends RecyclerView.Adapter<Myvh> {
#Override
public Myvh onCreateViewHolder(ViewGroup parent, int viewType) {
return new Myvh(new TextView(getContext()));
}
#Override
public void onBindViewHolder(Myvh holder, int position) {
int codepoint=pagePosition*700 + position;
char[] ch=Character.toChars(codepoint);
holder.textView.setText(String.valueOf(ch));
}
#Override
public int getItemCount() { return 700; }
}
private class Myvh extends RecyclerView.ViewHolder {
TextView textView;
public Myvh(View itemView) {
super(itemView);
textView = (TextView) itemView;
}
}
}
I have also tried Recyclerview adapter instead of FragmentStateAdapter and getting same problem.
I have found some solution but not sufficient.
Those are:
Using old ViewPager(deprecated)
Using viewPager.setOffscreenPageLimit(100); (taking huge time to load activity)
Disabling smoothscroll ( looks awful when swiping)

Convert ListView to RecyclerView

i have a list view in my app.
I want to change it to an recycler view, but even with different tutorials i dont get it.
I was using this: https://www.spreys.com/listview-to-recyclerview/
I failed with the "getView" part here.
Here is my code of the ListActivity and LeagueArrayAdapter.
Thanks for your help.
ListActivity:
public class ListActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
private ArrayAdapter adapter;
private final int REQUEST_CODE_EDIT = 1;
private static LeagueDAO leagueDAO;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
if (allLeagues1.size() == 0) {
leagueDAO.insert(new League("HVM Landesliga 19/20","https://hvmittelrhein-handball.liga.nu/cgi-bin/WebObjects/nuLigaHBDE.woa/wa/groupPage?championship=MR+19%2F20&group=247189"));
allLeagues1 = leagueDAO.getLeagues();
}
adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
ListView lv = findViewById(R.id.league_list);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
registerForContextMenu(lv);
Button btn_league_add = findViewById(R.id.btn_league_add);
btn_league_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ListActivity.this, EditActivity.class);
startActivity(intent);
}
});
}
#Override
public void onCreateContextMenu(ContextMenu contMenu, View v,
ContextMenu.ContextMenuInfo contextmenuInfo) {
super.onCreateContextMenu(contMenu, v, contextmenuInfo);
getMenuInflater().inflate(R.menu.team_list_context_menu, contMenu);
}
#Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo acmi=
(AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
League league = (League)adapter.getItem(acmi.position);
switch (item.getItemId()) {
case R.id.evliconit_edit:
editEntry(league, acmi.position);
return true;
case R.id.evliconit_del:
leagueDAO.delete(league);
adapter.remove(league);
adapter.notifyDataSetChanged();
return true;
default:
return super.onContextItemSelected(item);
}
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
League team = (League)adapter.getItem(position);
editEntry(team, position);
}
private void editEntry(League league, int position) {
Intent intent = new Intent(this, EditActivity.class);
intent.putExtra("team", league);
intent.putExtra("position", position);
startActivityForResult(intent, REQUEST_CODE_EDIT);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
if (requestCode == REQUEST_CODE_EDIT && resultCode == RESULT_OK && intent != null) {
Bundle extras = intent.getExtras();
int position = extras.getInt("position");
League league = (League) adapter.getItem(position);
league.setLeague_name(extras.getString("league_name"));
league.setLeague_url(extras.getString("league_url"));
adapter.notifyDataSetChanged();
}
}
#Override
protected void onRestart() {
super.onRestart();
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
ListView lv = findViewById(R.id.league_list);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
registerForContextMenu(lv);
}
LeagueArrayAdapter:
public class LeagueArrayAdapter extends ArrayAdapter<League> {
private List<League> leagues;
private Context context;
private int layout;
public LeagueArrayAdapter(Context context, int layout, List<League> leagues) {
super(context, layout, leagues);
this.context = context;
this.layout = layout;
this.leagues = leagues;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
League league = leagues.get(position);
if (convertView == null)
convertView = LayoutInflater.from(context).inflate(layout, null);
TextView tv_name = convertView.findViewById(R.id.tv_name);
TextView tv_url = convertView.findViewById(R.id.tv_url);
tv_name.setText(league.getLeague_name());
tv_url.setText(league.getLeague_url());
return convertView;
}
}
Update: app crashed when opened the activity
public class ListActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
private ArrayAdapter adapter;
private final int REQUEST_CODE_EDIT = 1;
private static LeagueDAO leagueDAO;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
if (allLeagues1.size() == 0) {
leagueDAO.insert(new League("HVM Landesliga 19/20","https://hvmittelrhein-handball.liga.nu/cgi-bin/WebObjects/nuLigaHBDE.woa/wa/groupPage?championship=MR+19%2F20&group=247189"));
allLeagues1 = leagueDAO.getLeagues();
}
// adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
RecyclerView lv = findViewById(R.id.league_list);
lv.setHasFixedSize(true);
lv.setLayoutManager(new LinearLayoutManager(this));
lv.setAdapter(new LeagueArrayAdapter(allLeagues1));
// lv.setOnItemClickListener(this);
registerForContextMenu(lv);
Button btn_league_add = findViewById(R.id.btn_league_add);
btn_league_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ListActivity.this, EditActivity.class);
startActivity(intent);
}
});
}

I reconstructed your ListView Adapter using RecyclerView.Adapter.
onCreateView is called for every visible container on your screen. If your screen can show 10 rows of data RecyclerView makes 11 - 12 containers (ViewHolder)
onBindView updates those containers with new data when you scroll.
MyViewHolder is the object that holds data about every row of data (container)
static class and bind() function inside to avoid any memory leak in your adapter.
We have access to Context in RecyclerView.Adapter using itemView and parent
itemView is the inflated View for each container (ViewHolder).
Initialize your Views inside ViewHolder's constructor so they get assigned once.
public class LeagueArrayAdapter extends RecyclerView.Adapter<LeagueArrayAdapter.MyViewHolder> {
private ArrayList<League> leagues;
public LeagueArrayAdapter(ArrayList<League> leagues) {
this.leagues = leagues;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
return LayoutInflater.from(parent.getContext()).inflate(R.layout.row_league, parent, false);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
holder.bind(leagues.get(position));
}
#Override
public int getItemCount() {
return 0;
}
static class MyViewHolder extends RecyclerView.ViewHolder {
TextView tv_name;
TextView tv_url;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
tv_name = itemView.findViewById(R.id.tv_name);
tv_url = itemView.findViewById(R.id.tv_url);
}
void bind(League league) {
tv_name.setText(league.getLeague_name());
tv_url.setText(league.getLeague_url());
}
}
}
Your Activity:
LinearLayoutManager for a linear layout
GridLayoutManager for a grid layout
setHasFixedSize() enhances your RecyclerView's speed if you are sure the RecyclerView itself won't change width or height.
public class LeagueActivity extends AppCompatActivity {
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.YOUR_ACTIVITY_LAYOUT_ID);
...
RecyclerView recyclerView = findViewById(R.id.YOUR_RECYCLER_VIEW_ID);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(new LeagueArrayAdapter(SEND_YOUR_ARRAY_OF_LEAGUE));
}
}

I suggest checking the Groupie Lbrary, it works with recyclerView and it makes life much easier for you, here is an example of how you can use it (I'm writing the code in kotlin but it shouldn't be that different from java)
first, add those lines to your Build.gradle (app) file
implementation 'com.xwray:groupie:2.3.0'
implementation 'com.xwray:groupie-kotlin-android-extensions:2.3.0'
then inside your activity create an adapter then set the adapter to your recyclerView
val myAdapter = GroupAdapter<ViewHolder>()
recyclerView.adapter = myAdapter
and just like this you set the adapter to your recyclerView, but you have to create "Items" to put inside the recyclerView. you can create an Item like so
class MyItem: Item() {
override fun getLayout() = R.layout.layout_seen
override fun bind(viewHolder: ViewHolder, position: Int){
}
}
in the getLayout method, you return the layout that you to display inside the recyclerView,
you can use the bind method to do any kind of modifications we want to apply to our layout that we are displaying.
lastly, we can add our items to the adapter this way
myAdapter.add(MyItem())
myAdapter.notifyDataSetChanged()
for more details check the library, in here I just explained how you can simply add an item to your RecyclerView

Listen Dialog Positive button click in each ViewPager fragment

I'm testing a function of listening the AlertDialog button click (Positive & Neutral) in each ViewPager fragment. And I am using the Interface method right now but getting some troubles.
So the structure is like this, I have an AlertDialog created by DialogFragment, and I put a ViewPager with two fragments into this DialogFragment. My goal is, when I click on the Positive button on the AlertDialog, I want some methods inside those two ViewPager fragments get called so that I can collect the data on those fragments.
Now the problem is, only the second fragment responses, I don't know why.
Here are the codes:
I created an Interface file
public interface Communicator {
void onConfirmClick();
}
I have a DialogFragment
public class MainDialogFragment extends DialogFragment {
View dialogLayout;
Communicator communicator;
#Override
public void onAttachFragment(Fragment childFragment) {
communicator = (Communicator) childFragment;
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return dialogLayout;
}
#NonNull
#Override
public Dialog onCreateDialog(#Nullable Bundle savedInstanceState) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(getActivity());
dialogLayout = getActivity().getLayoutInflater().inflate(R.layout.dialog_main, null);
ViewPager viewPager = dialogLayout.findViewById(R.id.main_viewPager);
final MainPagerAdapter adapter = new MainPagerAdapter(getChildFragmentManager());
viewPager.setAdapter(adapter);
dialogBuilder.setView(dialogLayout);
dialogBuilder.setPositiveButton("Confirm", null);
dialogBuilder.setNegativeButton("Cancel", null);
dialogBuilder.setNeutralButton("Change", null);
final AlertDialog dialog = dialogBuilder.create();
dialog.setOnShowListener(new DialogInterface.OnShowListener() {
#Override
public void onShow(DialogInterface dialogInterface) {
dialog.getButton(DialogInterface.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
communicator.onConfirmClick();
}
});
dialog.getButton(DialogInterface.BUTTON_NEUTRAL).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(view.getContext(), "Change click!!", Toast.LENGTH_SHORT).show();
}
});
}
});
return dialog;
}
}
My fragment A
public class MainFragmentA extends Fragment implements Communicator{
View rootView;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_a, container, false);
return rootView;
}
#Override
public void onConfirmClick() {
Toast.makeText(getContext(), "Fragment A!!", Toast.LENGTH_SHORT).show();
}
}
My fragment B
public class MainFragmentB extends Fragment implements Communicator{
View rootView;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_b, container, false);
return rootView;
}
#Override
public void onConfirmClick() {
Toast.makeText(getContext(), "Fragment B!!", Toast.LENGTH_SHORT).show();
}
}
My ViewPager adapter used inside DialogFragment
public class MainPagerAdapter extends FragmentPagerAdapter {
public MainPagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new MainFragmentA();
case 1:
return new MainFragmentB();
default:
throw new IllegalArgumentException("Wrong position!!");
}
}
#Override
public int getCount() {
return 2;
}
}
My MainActivity
public class MainActivity extends AppCompatActivity{
Button showDialogButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
showDialogButton = findViewById(R.id.main_show_dialog_button);
showDialogButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
MainDialogFragment mainDialogFragment = new MainDialogFragment();
mainDialogFragment.show(getSupportFragmentManager(), "mainDialogFragment");
}
});
}
}
Anyone can help? I'll so appreciate that!!!

Use a collection of some sort of Communicator interfaces instead of a single one. You're overwriting the communicator every time a child fragment is attached.
public class MainDialogFragment extends DialogFragment {
View dialogLayout;
List<Communicator> communicators = new ArrayList<>();
#Override
public void onAttachFragment(Fragment childFragment) {
communicators.add((Communicator) childFragment);
}
// all the other things from the MainDialogFragment...
}
And in the BUTTON_POSITIVE callback iterate through the list.
dialog.getButton(DialogInterface.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
for (Communicator communicator : communicators) {
communicator.onConfirmClick();
}
}
});

Only the communicator from the second fragment works
This is because you have two different instances of communicator in each of your fragments. As you are setting up the ViewPager, the second fragment is the last one that is being attached with the parent fragment. Hence, the communicator that you are initializing inside the onAttachFragment function of your MainDialogFragment class, is storing the reference from the second fragment only as this was the last one to be attached here.
In your case, I would rather suggest a very simple implementation using the lifecycle functions of the Fragment. Just take a public static variable in your MainDialogFragment class which will indicate if the okay button was clicked or not. And then check the value of that variable from each of your Fragment class inside the onResume function and perform the tasks accordingly. To get an idea of the implementation, please check the following.
Get a variable in your MainDialogFragment class like the following.
public static boolean isDialogOkayClicked = false; // Default false
Now in your MainFragmentA, implement the onResume function and check the value from the MainDialogFragment. Take the actions accordingly.
public class MainFragmentA extends Fragment implements Communicator{
View rootView;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_a, container, false);
return rootView;
}
#Override
protected void onResume() {
super.onResume();
if(MainDialogFragment.isDialogOkayClicked)
doSomething();
}
#Override
public void onConfirmClick() {
Toast.makeText(getContext(), "Fragment A!!", Toast.LENGTH_SHORT).show();
}
}
Do the same thing for your other fragment.
Hope that helps!

ViewPager setCurrentItem(position) not working after orientation change

i'm facing an issue i can't seem to resolve and i'd like some help.
My app is composed by an activity containing a fragment. After the user taps on a suggestion, activity's method onSuggestionClicked(String cardId) is called and activity's content is replaced with a new PagerFragment_new.
#Override
public void onSuggestionClicked(String cardId) {
Log.d("activity","ID:\t" + cardId);
PagerFragment_new pagerFragment = PagerFragment_new.getInstance(
Injection.provideMtgDatabase(getApplicationContext()),
activityPresenter.getAllCardExpansionIds(cardId),
this);
ActivityUtils.replaceFragment(getSupportFragmentManager(), pagerFragment, R.id.MTGRecallActivity_container);
}
PagerFragment_new contains a ViewPager to display CardInfoFragment_new
public class PagerFragment_new extends MtgRecallFragment_new implements PagerFragmentContract.View {
private View fragmentView;
private ViewPager viewPager;
private PagerFragmentContract.Presenter presenter;
private ScreenSlidePageAdapter_new adapter;
private MtgDatabase database;
private String[] printingsIds;
private ScreenSlidePageAdapter_new.ActivePresenterListener listener;
public PagerFragment_new() {
//Required empty constructor
}
public static PagerFragment_new getInstance(MtgDatabase database, String[] printingsIds, ScreenSlidePageAdapter_new.ActivePresenterListener listener) {
PagerFragment_new instance = new PagerFragment_new();
instance.setDatabase(database);
instance.setPrintingsIds(printingsIds);
instance.listener = listener;
return instance;
}
//other stuff
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
setRetainInstance(true);
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
setHasOptionsMenu(true);
fragmentView = inflater.inflate(R.layout.fragment_pager, container, false);
viewPager = (ViewPager) fragmentView.findViewById(R.id.PAGERFRAG_VIEWPAGER);
adapter = new ScreenSlidePageAdapter_new(getChildFragmentManager(), printingsIds, database, viewPager);
adapter.setListener(listener);
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(1);
return fragmentView;
}
#Override
public void setPresenter(PagerFragmentContract.Presenter presenter) {
this.presenter = presenter;
}
}
The adapter to manage ViewPager's element's is ScreenSlidePageAdapter_new, it is responsible of instantiating CardInfoFragments.
public class ScreenSlidePageAdapter_new extends FragmentStatePagerAdapter {
private String[] printingsIds;
private String firstItemId;
private MtgDatabase database;
public ActivePresenterListener activity;
private ViewPager viewPager;
public ScreenSlidePageAdapter_new(FragmentManager fm, String[] printingsIds, MtgDatabase database, ViewPager viewPager) {
super(fm);
this.printingsIds =printingsIds;
this.database = database;
this.firstItemId = printingsIds[0];
this.viewPager = viewPager;
}
#Override
public Fragment getItem(int position) {
//todo create a bundle with cardId
Bundle bundle = new Bundle();
bundle.putString("CardID", printingsIds[position]);
bundle.putString("FirstItemId", firstItemId);
CardInfoFragment_new cardInfoFragment_new = CardInfoFragment_new.getInstance(viewPager);
cardInfoFragment_new.setArguments(bundle);
CardInfoPresenter cardInfoPresenter = new CardInfoPresenter(cardInfoFragment_new, database);
activity.setActivePresenter(cardInfoPresenter);
return cardInfoFragment_new;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
public void setListener(ActivePresenterListener listener) {
this.activity = listener;
}
#Override
public int getCount() {
return printingsIds.length;
}
public interface ActivePresenterListener {
void setActivePresenter(BasePresenter presenter);
}}
Finally, here's the code of CardInfoFragment:
public class CardInfoFragment_new extends MtgRecallFragment_new
implements CardInfoContract.View,
CardPrintingsAdapter.OnItemClickListener {
private ViewPager viewPager;
public CardInfoContract.Presenter presenter;
private View fragmentView;
private MTGCard mtgCard;
RecyclerView printingsRecyclerView;
CardPrintingsAdapter cardPrintingsAdapter;
private String firstItemId; //the first id
public CardInfoFragment_new() {
//required empty constructor
}
private void setViewPager(ViewPager viewPager) {
this.viewPager = viewPager;
}
public static CardInfoFragment_new getInstance(ViewPager viewPager) {
CardInfoFragment_new cardInfoFragment_new = new CardInfoFragment_new();
cardInfoFragment_new.setViewPager(viewPager);
return cardInfoFragment_new;
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
setRetainInstance(true);
presenter.start();
String cardId = getArguments().getString("CardID");
firstItemId = getArguments().getString("FirstItemId");
mtgCard = presenter.getCardData(cardId);
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
fragmentView = inflater.inflate(R.layout.fragment_card_info_new, container, false);
setUpCardInfoView(fragmentView);
return fragmentView;
}
public void setUpCardInfoView(final View view){
//others view set-up action omitted
cardprintingsContainer = (LinearLayout) view.findViewById(R.id.CARDINFO_printingsContainer);
printingsRecyclerView = (RecyclerView)fragmentView.findViewById(R.id.CARDINFO_printings_recyclerView);
final List<String> printings = presenter.getCardPrintings(firstItemId, mtgCard.getName());
if (printings.size() < 40) {
setupPrintings(printings,printingsRecyclerView);
}
else {
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LinearLayout printingsRow = new LinearLayout(getContext());
printingsRow = (LinearLayout)inflater.inflate(R.layout.card_info_printings_row,printingsRow,true);
printingsRow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
setupPrintings(printings, printingsRecyclerView);
}
});
ImageView printingssetImage = (ImageView)printingsRow.findViewById(R.id.CARDINFO_printingsRow_setImage);
printingssetImage.setVisibility(View.INVISIBLE);
TextView printingssetName = (TextView)printingsRow.findViewById(R.id.CARDINFO_printingsRow_setName);
printingssetName.setText("Click to see all the "+printings.size()+ " versions");
cardprintingsContainer.addView(printingsRow);
}
}
public void setupPrintings(List<String> printings, RecyclerView recyclerView) {
cardPrintingsAdapter =
new CardPrintingsAdapter(getContext(), printings);
cardPrintingsAdapter.setOnItemClickListener(this);
UnscrollableLayoutManager layoutManager = new UnscrollableLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
recyclerView.setAdapter(cardPrintingsAdapter);
recyclerView.setLayoutManager(layoutManager);
}
#Override
public void onItemClick(View itemView, int position) {
int i = viewPager.getAdapter().getCount();
viewPager.setCurrentItem(position);
}
#Override
public void onDestroy() {
presenter = null;
mtgCard = null;
super.onDestroy();
}}
When user click on a RecyclerView item, CardInfoFragment's method onItemClick(View itemView, int position) is called and the viewpager is set to current position. Everything as expected.
THE PROBLEM
When the orientation changes, fragments are able to retain their states, but viewPager.setCurrentItem(position) does nothing, and i'm not able to change displayed fragment.
I already checked:
ViewPager instance and adapters instances corresponds to those passed to Fragments
onItemClick is fired
this questions question1 question2
If i use
android:configChanges="orientation|screenSize"
in manifest it works even after config changes, but i don't want to use this option since is discouraged.
Thanks in advance!

By default, when certain key configuration changes happen on Android (a common example is an orientation change), Android fully restarts the running Activity to help it adjust to such changes.
When you define android:configChanges="keyboardHidden|orientation" in your AndroidManifest, you are telling Android: "Please don't do the default reset when the keyboard is pulled out, or the phone is rotated; I want to handle this myself. Yes, I know what I'm doing".
So use configChanges.
The use of this is discouraged, IF you don't know how to use it. But for a case like this, I would suggest you use it. IF not, still the activity will be recreated. which just takes time, resources, and I don't see why you would want that to happen.

Where to place EventBus.getDefault().unregister in BaseAdapter

Friends, I've spent enough time to find an answer to my question(here and on android's site) But no luck.
Here is the logic:
From DialogFragment upon finishing putting user's data he clicks OK button:
import de.greenrobot.event.EventBus;
...
public class AddDialogFragment extends DialogFragment implements
DialogInterface.OnClickListener {
...
public void onClick(DialogInterface dialog, int which) {
StringBuilder date = new StringBuilder(today.getText().subSequence(0,
today.getText().length()));
date = (date.toString().equals(getString(R.string.today))) ? new StringBuilder("20150104") : date;
int weight = 89;
String[] bsi = rb.getSelectedItems();
String[] gsi = rg.getSelectedItems();
DatabaseManipulation dm = new DatabaseManipulation(getActivity());
dm.run(date, weight, bsi, gsi);
dm.destroy();
DialogDataModel toSend = new DialogDataModel(weight, date.toString(), bsi, gsi);
/*
Context activity = getActivity();
if (activity instanceof WDActivity)
((WDActivity) activity).updateListItemFragment();
*/
EventBus.getDefault().post(new UpdateItemEvent(toSend));
Log.d(LOG_TAG, "send event");
Toast.makeText(getActivity(), R.string.saved_data, Toast.LENGTH_LONG).show();
}
...
Event is successfully sent to Adapter class which is registered for receiving this event:
...
import de.greenrobot.event.EventBus;
public class ItemsAdapter extends BaseAdapter implements ListAdapter {
private static final String LOG_TAG = "Logs";
private ArrayList<DialogDataModel> list = new ArrayList<DialogDataModel>();
private Context activity;
public ItemsAdapter (ArrayList<DialogDataModel> list, Context context) {
this.list = list;
this.activity = context;
registerEventBus();
}
#Override
public int getCount() {
return list.size();
}
#Override
public Object getItem(int pos) {
return list.get(pos);
}
#Override
public long getItemId(int pos) {
return pos;
//just return 0 if your list items do not have an Id variable.
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.row_item, null);
}
DialogDataModel curData = list.get(position);
TextView itemDate = (TextView)view.findViewById(R.id.item_date);
itemDate.setText(curData.getDate());
TextView itemWeight = (TextView)view.findViewById(R.id.item_weight);
itemWeight.setText( Integer.toString(curData.getWeight()) );
TextView itemEvents = (TextView)view.findViewById(R.id.item_events);
itemEvents.setText(curData.getEventsShort());
//Handle buttons and add onClickListeners
ImageButton editBtn = (ImageButton)view.findViewById(R.id.item_edit_btn);
editBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (activity instanceof WDActivity)
((WDActivity) activity).AddNewData(v, list.get(position));
notifyDataSetChanged();
}
});
ImageButton deleteBtn = (ImageButton) view.findViewById(R.id.item_delete_btn);
deleteBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String date = list.get(position).getDate();
DatabaseManipulation dm = new DatabaseManipulation(activity);
dm.deleteItem(date);
dm.destroy();
list.remove(position);
notifyDataSetChanged();
}
});
return view;
}
public void registerEventBus(){
if (!EventBus.getDefault().isRegistered(this)) EventBus.getDefault().register(this);
Log.d(LOG_TAG, "Registred from adapter");
}
public void unregisterEventBus(){
EventBus.getDefault().unregister(this);
}
public void onEventMainThread(UpdateItemEvent event) {
Log.d(LOG_TAG, "Event fired!");
list = DialogDataModel.replaceFieldsInArray(list,event.getModel());
notifyDataSetChanged();
}
}
After clicking OK in dialog window the user sees the list of items and the item he's updated is up to date. Without this logic he sees the old version of this item item in the list and to refresh the list he needs to relaunch the app.
Yes, it's working with EventBus.
But as you can see here in the class there is no place for unregistering it from listening for UpdateItemEvent. Since there are no destructors in java(I don't believe that garbage collector should do this for me) I should handle this. Moreover the class registeres as listener in constructor (it happens several times, that's why you see this ugly if statement(if (!EventBus.getDefault().isRegistered(this))) You may ask me why not getting this adapter through Activity (there is the only one in the app) I tried building a chain AddDialogFragment -> WDActivity -> PlaceholderFragment -> ItemsAdapter
//AddDialogFragment
Context activity = getActivity();
if (activity instanceof WDActivity)
((WDActivity) activity).updateListItemFragment();
//WDActivity --beginTransaction().replace does not work here
...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_wd);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
...
public void updateListItemFragment() {
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.Fragment currentFragment = fragmentManager.findFragmentById(R.id.container);
if (currentFragment instanceof PlaceholderFragment && currentFragment != null) {
fragmentManager.beginTransaction().remove(currentFragment).commit();
fragmentManager.beginTransaction().add(R.id.container, currentFragment).commit();
((PlaceholderFragment)currentFragment).fillList();
}
//PlaceholderFragment
public class PlaceholderFragment extends Fragment {
private static final String LOG_TAG = "Logs";
private static final String ARG_SECTION_NUMBER = "section_number";
private ListView listViewItem;
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(getArguments().getInt(ARG_SECTION_NUMBER)==1)
return onCreateViewInputChart(inflater, container, savedInstanceState);
if(getArguments().getInt(ARG_SECTION_NUMBER)==2)
return onCreateViewManual(inflater, container, savedInstanceState);
return onCreateViewInputData(inflater, container, savedInstanceState);
}
private View onCreateViewManual(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_howto, container, false);
return rootView;
}
private View onCreateViewInputData(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_list_data, container, false);
findViewsByIdListItem(rootView);
fillList();
return rootView;
}
private View onCreateViewInputChart(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_chart, container, false);
return rootView;
}
//listViewItems
private void findViewsByIdListItem(View v) {
listViewItem = (ListView) v.findViewById(R.id.listViewItems);
}
public void fillList(){
Context activity = getActivity();
DatabaseManipulation dm = new DatabaseManipulation(activity);
ArrayList<DialogDataModel> aldm = dm.getItemsList();
dm.destroy();
ItemsAdapter innerAdapter = new ItemsAdapter(aldm, activity);
listViewItem.setAdapter(innerAdapter);
( (BaseAdapter) listViewItem.getAdapter() ).notifyDataSetChanged();
}
#Override
public void onAttach(Context activity) {
super.onAttach(activity);
}
#Override
public void onDetach(){
super.onDetach();
}
}
//SectionsPagerAdapter - just for your information
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
return PlaceholderFragment.newInstance(position);
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Enter your data";
case 1:
return "Chart";
case 2:
return "How to use it";
}
return null;
}
}
//ItemsAdapter is placed higher
This did not work. Finally I found out that the bottleneck is in linking PlaceholderFragment and ListAdapter: listViewItem is null everywhere except onCreateViewInputData. I could not figure out why. Google didn't give me the answer and I took it as a magic. Btw due to this feature I cannot use PlaceholderFragment's onAttach and onDetach for saying ItemsAdapter to register/unregister for receiving the event. This:
#Override
public void onAttach(Context activity) {
super.onAttach(activity);
( (ItemsAdapter) listViewItem.getAdapter() ).registerEventBus();
}
doesn't work for the same reason listViewItem is null. Maybe there is some way to manage with this more accurately?

Finally I cope with this: the bottleneck is in linking PlaceholderFragment and ListAdapter: listViewItem is null everywhere except onCreateViewInputData . Below is rewised SectionsPagerAdapter:
public class SectionsPagerAdapter extends FragmentPagerAdapter {
Context activity;
SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
public SectionsPagerAdapter(FragmentManager fm, Context activity) {
super(fm);
this.activity = activity;
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
return PlaceholderFragment.newInstance(position);
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return activity.getString(R.string.chart);
case 1:
return activity.getString(R.string.weight_diary);
case 2:
return activity.getString(R.string.how_to);
}
return null;
}
#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);
//maybe use adapater.getRegisteredFragment(viewPager.getCurrentItem());
}
}
and here is my call to the widget in the one of 3 fragments:
public void updateListItemFragment() {
android.support.v4.app.Fragment inputData = mSectionsPagerAdapter.getRegisteredFragment(1);
ListView lv = ((PlaceholderFragment)inputData).listViewItem;
//for test purposes I refill listview with no items - here you need to hand filled BaseAdapter instance: CustomAdapter innerAdapter = new CustomAdapter(ArrayList<yourDataModel>, getContext());
lv.setAdapter(null);
}
And as you've may already wondered there is no need for event bus anymore. Btw if the fragment is not crated yet you need to check it: details are here. Thanks to CommonsWare for quik reply and advice.