I need help with reloading a Fragment that is part of a ViewPager. Here is my current setup:
ReportActivity extends FragmentActivity and uses ViewPager to host 4 Tabs
TAB 1 to 4. Each Tab is a Fragment with seperate layout.
ViewPager uses TabsPagerAdapter to switch between the tabs and this works as expected.
TAB1Fragment displays a graph using a static dataset. Now I have added a spinner to dynamically change the dataset and I am looking for ways to reload the Fragment so it can re-display the graph with the correct dataset. The following ints correspond to the values of the Spinner.
static final int REPORT_PERIOD_DAY = 0;
static final int REPORT_PERIOD_WEEK = 1;
static final int REPORT_PERIOD_MONTH = 2;
static final int REPORT_PERIOD_YEAR = 3;
I have a method that correctly calculates the correct data based on the the int passed in, what I am struggling with is how to create an Intent or any other method that will recreate TAB1Fragment and passes it an int parameter.
Here is where I want to re-create the Fragment
mReportPeriodSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
switch (position){
case 0:
//How can I re-load the Fragment here?
reloadFragment(REPORT_PERIOD_DAY);
break;
case 1:
reloadFragment(REPORT_PERIOD_WEEK);
break;
case 2:
reloadFragment(REPORT_PERIOD_MONTH);
break;
case 3:
reloadFragment(REPORT_PERIOD_YEAR);
break;
}
}
Please can you give me an idea of how to write the code that goes into the method reloadFragment(Int period)
I would recommend re-configuring the existing fragment, rather than constructing a new fragment with the new report period.
I'm guessing that you currently configure your graph inside TAB1Fragment's onCreateView. If you move that configuration code to onResume, then you can call the same function when the user selects something in the spinner.
public class TAB1Fragment extends Fragment {
int reportPeriod;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = ...
reportPeriod = REPORT_PERIOD_DAY; // default report period
return rootView;
}
#Override
public void onResume() {
super.onResume();
configureGraph();
}
private void configureGraph() {
//TODO put all the code that draws your graphs here, using reportPeriod
}
public void reloadFragment(int reportPeriod) {
this.reportPeriod = reportPeriod;
configureGraph();
}
}
If this approach really doesn't work for you, and you really need a new fragment each time, then this question explains how to get the tag for a fragment so that you can tell the FragmentManager to replace it:
Replace Fragment inside a ViewPager
Related
With Fragment:setRetainInstance(true); the fragment is not re-instantiated on a phones orientation change.
And of course i want my fragments to be kept alive while switching from one fragment to another.
But the Android Studio 4 provides a wizard-template with only
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
From hours of debugging and searching the net if think it would need to inherent from the class FragmentNavigator so i can overwrite FragmentNavigator:naviagte where a new fragment gets created via final Fragment frag = instantiateFragment(.. and then is added with ft.replace(mContainerId, frag);
So i could find my old fragment and use ftNew.show and ftOld.hide instead.
Of course this is a stupid idea, because this navigate method is full of other internal stuff.
And i have no idea where that FrameNavigator is created.
I can retrieve it in the MainActivity:OnCreate with
NavigatorProvider navProvider = navController.getNavigatorProvider ();
Navigator<NavDestination> navigator = navProvider.getNavigator("fragment");
But at that time i could only replace it with my derived version. And there is no replaceNavigtor method but only a addNavigator method, which is called where ?
And anyways this all will be far to complicated and therefore error prone.
Why is there no simple option to keep my fragments alive :-(
In older Wizard-Templates there was the possibility of
#Override
public void onNavigationDrawerItemSelected(int position) {
Fragment fragment;
switch (position) {
case 1:
fragment = fragment1;
break;
case 2:
fragment = fragment2;
break;
case 3:
fragment = fragment3;
break;
}
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if(mCurrentFragment == null) {
ft.add(R.id.container, fragment).commit();
mCurrentFragment = fragment;
} else if(fragment.isAdded()) {
ft.hide(mCurrentFragment).show(fragment).commit();
} else {
ft.hide(mCurrentFragment).add(R.id.container, fragment).commit();
}
mCurrentFragment = fragment;
}
but i have no idea how to do this with the Android 4.0 template where my MainActivity is only derived as:
public class MainActivity extends AppCompatActivity {
private AppBarConfiguration mAppBarConfiguration;
Ideas welcome :'(
Hi there & sorry for my late answer! I had a similar problem with navigation drawers and navigation component. I tried around a little and found a working solution, which might be helpful for others too.
The key is the usage of a custom FragmentFactory in the FragmentManager of the MainActivity. See the code for this below:
public class StaticFragmentFactory extends FragmentFactory {
private myNavHostFragment1 tripNavHostFragment;
private myNavHostFragment2 settingsNavHostFragment;
#NonNull
#Override
public Fragment instantiate(#NonNull ClassLoader classLoader, #NonNull String className) {
if (MyNavHostFragment1.class.getName().equals(className)) {
if (this.myNavHostFragment1 == null) {
this.myNavHostFragment1 = new MyNavHostFragment1();
}
return this.myNavHostFragment1 ;
} else if (MyNavHostFragment2.class.getName().equals(className)) {
if (this.myNavHostFragment2 == null) {
this.myNavHostFragment2 = new MyNavHostFragment2();
}
return this.myNavHostFragment2;
}
return super.instantiate(classLoader, className);
}
}
The FragmentFactory survives the navigation between different fragments using the NavigationComponent of AndroidX. To keep the fragments alive, the FragmentFactory stores an instance of the fragments which should survive and returns this instance if this is not null. You can find a similar pattern when using a singleton pattern in classes.
You have to register the FragmentFactory in the corresponding activity by calling
this.getSupportFragmentManager().setFragmentFactory(new StaticFragmentFactory())
Please note also that I'm using nesten fragments here, so one toplevel fragment (called NavHostFragmen here) contains multiple child fragments. All fragments are using the same FragmentFactory of their parent fragments. The custom FragmentFactory above returns the result of the super class method, when the fragment to be instantiated is not known to keep alive.
I'm using a spinner in the menu of a fragment, load its data in the onCreateView. It works fine when the app is launched,however, the spinner disappears when the user navigates to a different fragment and comes back or when the app is opened the next time.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
setHasOptionsMenu(true);
getSpinnerValues(); //string request to add values to TrailList
}
#Override // ...
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.map_menu, menu);
super.onCreateOptionsMenu(menu, inflater); //temp
//setData();
final MenuItem item = menu.findItem(R.id.trailfiller);
mySpinner = (Spinner) MenuItemCompat.getActionView(item);
ArrayAdapter<Trail> adapter = new ArrayAdapter<Trail>(getContext(), android.R.layout.simple_spinner_dropdown_item, TrailList);
mySpinner.setAdapter(adapter);
mySpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
Trail country = (Trail) parent.getSelectedItem();
Toast.makeText(getContext(), ""+country.getId()+""+country.getName(), Toast.LENGTH_SHORT).show();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
The moment it goes blank, the onItemSelected isn't getting triggered either.Strange thing to note is the spinner is consistent when the values are hardcoded. What am I missing here?
The onItemSelected would get triggered.Problem was with the ArrayList of size 0. Populating it inside the onCreateOptionsMenu will help. Alternatively,you can add an item to the list inside the onCreateOptionsMenu, which will help you get rid of this issue
Spinner spinner= new Spinner();
spinner.setName("select a country");
TrailList.add(spinner);
I'm using viewpager to display pictures. I just need three fragments basically: previous image to preview, current display image and next image to preview. I would like to just display a preview of previous and next image, it will change to full image when user actually swipe to it. So I'm thinking of just using 3 fragment to achieve this. Code is below:
private class ImagePagerAdapter extends FragmentStatePagerAdapter implements ViewPager.OnPageChangeListener {
private ImageFragment mImageFragment;
private ImagePreviewFragment mPreviousPreviewFragment;
private ImagePreviewFragment mNextPreviewFragment;
public ImagePagerAdapter(FragmentManager fm, ImageFragment image, ImagePreviewFragment previous, ImagePreviewFragment next) {
super(fm);
mImageFragment = image;
mPreviousPreviewFragment = previous;
mNextPreviewFragment = next;
}
#Override
public Fragment getItem(int position) {
if (position == mPager.getCurrentItem()) {
mImageFragment.display(position);
return mImageFragment;
}
if (position < mPager.getCurrentItem()) {
mPreviousPreviewFragment.display(position - 1);
return mPreviousPreviewFragment;
}
mNextPreviewFragment.display(position + 1);
return mNextPreviewFragment;
}
#Override
public int getCount() {
return 100;
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
Log.d(TAG, "onPageScrolled");
}
#Override
public void onPageSelected(final int position) {
Log.d(TAG, "onPageSelected " + position);
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
notifyDataSetChanged();
}
}, 500);
}
#Override
public void onPageScrollStateChanged(int state) {
Log.d(TAG, "onPageScrollStateChanged " + state);
}
#Override
public int getItemPosition(Object item) {
return POSITION_NONE;
//return POSITION_UNCHANGED;
}
}
So basically, I pre-created three fragments to display previous/next preview and current image and return them for getItem(). I also notifydatasetchange() in onpageselected() to make all three position to update the fragment when user swipe to new page.
But the problem is that it will throw out
Fragment already added IllegalStateException
when the fragments are added a second time. I think it's because it's been added before. I can create a new fragment every time but I think that's wasteful. So how can I reuse the already created fragment and just update them?
Thanks,
Simon
FragmentStatePagerAdapter design suggests creating a new Fragment for every page (see Google's example). And unfortunately you cannot readd a Fragment once it was added to a FragmentManager (what implicitly happens inside adapter), hence the exception you got. So the official Google-way is to create new fragments and let them be destroyed and recreated by the adapter.
But if you want to reuse pages and utilize an analogue of ViewHolder pattern, you should stick to views instead of fragments. Views could be removed from their parent and reused, unlike fragments. Extend PagerAdapter and implement instantiateItem() like this:
#Override
public Object instantiateItem(ViewGroup container, final int position) {
//determine the view type by position
View view = viewPager.findViewWithTag("your_view_type");
if (view == null) {
Context context = container.getContext();
view = LayoutInflater.from(context).inflate(R.layout.page, null);
view.setTag("your_view_type");
} else {
ViewGroup parent = (ViewGroup) item.getParent();
if (parent != null) {
parent.removeView(item);
}
}
processYourView(position, view);
container.addView(view, MATCH);
return view;
}
You should add some extra logic to determine the view type by position (since you have 3 types of views), I think you can figure that out.
I have 3 ListFragments being handled by a viewPager (managed by a FragmentAdapter) - they work perfectly. Now when the user clicks an item in ListFragment #1, a new Fragment should open with the details. It's behaving strangely in the following manner:
Only clicking a list item twice opens the DetailFragment, yet debugging shows the first click indeed goes into the DetailFragment, but doesn't show the view (the view still shows the current ListFragment).
After clicking the 2nd time, the DetailFragment does show it's layout, but not the elements within it (like TextView, etc).
If the user 'accidently' swipes the screen when DetailFragment is showing, the viewPager sets it in place of the 2nd ListFragment! Only when pressing back on the DetailFragment view will 'reset' the viewPager to it's correct ListFragment. Of course if the user swipes when in a DetailFragment, the next ListFragment of the viewPager should appear, and the DetailFragment should be removed.
Thanks for any tips muddling through Android's odd world of fragments and views :)
public class PlanetFragment extends ListFragment{
LayoutInflater inflater;
ListView list;
ArrayList<HashMap<String, String>> planetListArray;
HashMap<String, String> planetMap;
Activity activity;
Context context;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.planets_tab_layout, container, false);
inflater=(LayoutInflater)getLayoutInflater(savedInstanceState);
activity = getActivity();
context = PlanetFragment.this.getActivity();
String dbTableName = "Table_Planets";
SQLiteHelper info = new SQLiteHelper(getActivity().getBaseContext());
info.open();
ArrayList<HashMap<String, String>> datafromSQL = info.getData(dbTableName);
if(!datafromSQL.isEmpty()){
planetListArray = new ArrayList<HashMap<String, String>>();
for (int i = 0; i<datafromSQL.size(); i++){
planetMap = new HashMap<String, String>();
planetMap.put(PLANET_ID, datafromSQL.get(i).get(KEY_PLANET_ID));
planetMap.put(ZODIAC_ID, datafromSQL.get(i).get(KEY_ZODIAC_ID));
planetMap.put(DEGREES, datafromSQL.get(i).get(KEY_DEGREES));
planetMap.put(CONTENT, datafromSQL.get(i).get(KEY_CONTENT));
planetListArray.add(planetMap);
}
info.close();
}
list = (ListView) v.findViewById(android.R.id.list);
PlanetAdapter adapter=new PlanetAdapter(getActivity(), R.layout.planets_row, planetListArray);
list.setAdapter(adapter);
return v;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//the dividers
getListView().setDivider(getResources().getDrawable(R.drawable.purplebartop));
}
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
HashMap<String, String> item = planetListArray.get(position);
Bundle bundle = new Bundle();
bundle.putSerializable("itemMap", item);
bundle.putInt("position", position);
Fragment frag = DetailFragment.newInstance();
frag.setArguments(bundle);
if (frag != null) {
getActivity().getSupportFragmentManager()
.beginTransaction()
.replace(R.id.pager, frag, "frag")
.addToBackStack("frag")
.commit();
}
}
}
public class DetailFragment extends Fragment{
Context context;
Activity activity;
TextView planetName;
public static android.support.v4.app.Fragment newInstance() {
DetailFragment f = new DetailFragment();
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
inflater=(LayoutInflater)getLayoutInflater(savedInstanceState);
View v = inflater.inflate(R.layout.dialog_details, container, false);
activity = getActivity();
context = DetailFragment.this.getActivity();
planetName = (TextView)v.findViewById(R.id.planetNameExpanded);
planetName.setText("planetX");
return v;
}
}
EDIT:
Instead of getActivity().getSupportFragmentManager() I have also tried getChildFragmentManager() but it always gives the error: The method getChildFragmentManager() is undefined for the type PlanetFragment.
When you click on a list item, you are indeed constructing a new details fragment and telling the fragment manager to replace the tag "frag" with that fragment. However, you are not telling the view pager to switch over to that fragment.
Since you already have a back-pointer to your activity, you could use findViewById to find your view pager, and then call viewPager.setCurrentItem.
I think you might be asking for trouble by constructing a new details fragment inside of the list fragment. When you use a FragmentPagerAdapter, the adapter usually constructs the fragments. I would have implemented this by letting the adapter make the fragments, and then in your onListItemClick find the existing details fragment and call a method on it to configure it with the new data. But maybe just the setCurrentItem will fix your problem.
EDIT
First, I would write your FragmentPagerAdapter so you can use getItem to fetch the existing fragment, without creating a new one each time.
public class PlanetFragmentAdapter extends FragmentPagerAdapter {
private Fragment [] fragments = new Fragments[3];
public PlanetFragmentAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return 3;
}
#Override
public Fragment getItem(int position) {
Fragment fragment = fragments[position];
if (fragment == null) {
switch (position) {
case 0:
fragment = new PlanetFragment();
break;
case 1:
fragment = new DetailFragment();
break;
case 2:
fragment = new MysteryFragment();
break;
}
fragments[position] = fragment;
}
return fragment;
}
}
Also add functions in your activity to work with your fragments:
public void setPage(int position) {
viewPager.setCurrentItem(position);
}
public DetailFragment getDetailFragment() {
return (DetailFragment) viewPager.getItem(1); // now it doesn't create a new instance
// you could also use getSupportFragmentManager().findFragmentById() here
}
Now when you click on an item in your list fragment, you can get the existing detail fragment, configure it, and set the ViewPager to show the detail fragment.
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
HashMap<String, String> item = planetListArray.get(position);
Bundle bundle = new Bundle();
bundle.putSerializable("itemMap", item);
bundle.putInt("position", position);
PlanetActivity pa = (PlanetActivity) activity;
DetailFragment frag = pa.getDetailFragment();
frag.setArguments(bundle);
pa.setCurrentItem(1);
}
I'm using the Android Studio provided class for a tabbed activity that uses Action Bar Tabs with ViewPager. Inside this activity, I'm trying to initialize a RecyclerView with data from a Firebase database.
Problem: On the app's first run, the RecyclerView is empty as shown below.
If I close and reopen the application from within the emulator, my RecyclerView gets populated as it should, as shown below.
Any ideas as to why this might be happening? I have a theory but I haven't been able to find a solution. After trying to read the FragmentPagerAdapter page, I got the impression that the fragments must be static (I don't know what the implications of this might be, so if anyone can shed some light on this it would be appreciated). On the app's first run, it initializes the RecyclerView. It then adds the data from the Firebase database but since the RecyclerView has already been initialized it is empty and is never properly updated. I tried calling the notify... methods to no avail.
StudentFragment's onCreateView method:
private View view;
private Context c;
private RecyclerView mRecyclerView;
private LinearLayoutManager manager;
private Firebase mFirebaseRef;
private FirebaseRecyclerAdapter<Student, ViewHolder> firebaseRecyclerAdapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_students, container, false);
mFirebaseRef = new Firebase("<your Firebase link here>");
c = getContext();
//Initializes Recycler View and Layout Manager.
mRecyclerView = (RecyclerView) view.findViewById(R.id.studentRecyclerView);
manager = new LinearLayoutManager(c);
mRecyclerView.setHasFixedSize(true);
firebaseRecyclerAdapter =
new FirebaseRecyclerAdapter<Student, ViewHolder>(
Student.class,
R.layout.single_student_recycler,
ViewHolder.class,
mFirebaseRef
) {
#Override
protected void populateViewHolder(ViewHolder viewHolder, Student student, int i) {
viewHolder.vFirst.setText(student.getFirst());
viewHolder.vLast.setText(student.getLast());
viewHolder.vDue.setText(Double.toString(student.getCurrentlyDue()));
viewHolder.vRadio.setButtonTintList(ColorStateList.valueOf(Color.parseColor(student.getColor())));
Log.d(TAG, "populateViewHolder called");
}
};
mRecyclerView.setAdapter(firebaseRecyclerAdapter);
mRecyclerView.setLayoutManager(manager);
return view;
}
ViewHolder:
public static class ViewHolder extends RecyclerView.ViewHolder {
public final TextView vFirst;
public final TextView vLast;
public final TextView vDue;
public final RadioButton vRadio;
public ViewHolder(View itemView) {
super(itemView);
vFirst = (TextView) itemView.findViewById(R.id.recycler_main_text);
vLast = (TextView) itemView.findViewById(R.id.recycler_sub_text);
vRadio = (RadioButton) itemView.findViewById(R.id.recycler_radio_button);
vDue = (TextView) itemView.findViewById(R.id.recycler_due_text);
}
Homescreen's onCreate method:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_homescreen);
// 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);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
}
Firebase context is set on another application that starts as soon as the Homescreen activity starts. Any help will be appreciated.
Edit: I was digging through the FirebaseUI GitHub page, which is where the problem most likely lies, and found another user with the exact same problem. It seems that onBindViewHolder isn't called after notifyItemInserted in the FirebaseRecyclerAdapter class. Now to fix it...
In my case this was caused by mRecyclerView.setHasFixedSize(true); If you comment out this line of code the list loads properly. I got my solution from this discussion: https://github.com/firebase/FirebaseUI-Android/issues/204
Let me try, as you say on the question title,
RecyclerView not displaying on application start
so, the
Initializes Recycler View and Layout Manager.
should be declared on the onStart
#Override
public void onStart() {
super.onStart();
mFirebaseRef = new Firebase("<your Firebase link here>");
firebaseRecyclerAdapter = ...
//and so on
Hope it helps!
firebaseRecyclerAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
#Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
int friendlyMessageCount = firebaseRecyclerAdapter.getItemCount();
int lastVisiblePosition =
linearLayoutManager.findLastCompletelyVisibleItemPosition();
// If the recycler view is initially being loaded or the
// user is at the bottom of the list, scroll to the bottom
// of the list to show the newly added message.
if (lastVisiblePosition == -1 ||
(positionStart >= (friendlyMessageCount - 1) &&
lastVisiblePosition == (positionStart - 1))) {
linearLayoutManager.scrollToPosition(positionStart);
}
}
});
recyclerListIdeas.setAdapter(firebaseRecyclerAdapter);
** Just add Recyclerview.AdapterDataObserver() . worked for me ! hope it helps :)**
i had the same issue, check the documentation:
https://codelabs.developers.google.com/codelabs/firebase-android/#6
fixed it by adding a data observer:
mFirebaseAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
#Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
int friendlyMessageCount = mFirebaseAdapter.getItemCount();
int lastVisiblePosition =
mLinearLayoutManager.findLastCompletelyVisibleItemPosition();
// If the recycler view is initially being loaded or the
// user is at the bottom of the list, scroll to the bottom
// of the list to show the newly added message.
if (lastVisiblePosition == -1 ||
(positionStart >= (friendlyMessageCount - 1) &&
lastVisiblePosition == (positionStart - 1))) {
mMessageRecyclerView.scrollToPosition(positionStart);
}
}
});