My app has a tablayout with a view pager. Each page has a fragment. There are 4 different fragments, three of them are basically the same for now (I'm in the development phase right now). One of them has a RecyclerView with a basic list.
I am implementing the Two-pane template in the fragment with the RecyclerView.
Everything seems to be works]ing well. While I move across the tabs the fragments are loaded fine.
But, when I rotate the device and tap on the first tab, and then go back to the one with the recyclerview, I can see the previous intance below. See attached images.
I decided to use static final instances of the fragments in the page adapter and in the recyclerview fragment.
How can I get rid of this problem?
Thanks in advance stackers!
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout tabLayout = findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setIcon(R.drawable.icon1).setText(R.string.dashboard));
tabLayout.addTab(tabLayout.newTab().setIcon(R.drawable.icon2).setText(R.string.fragment2));
tabLayout.addTab(tabLayout.newTab().setIcon(R.drawable.icon3).setText(R.string.fragmentDualPane));
tabLayout.addTab(tabLayout.newTab().setIcon(R.drawable.icon4).setText(R.string.frag4));
final ViewPager viewPager = findViewById(R.id.pager);
final PagerAdapter pageAdapter = new TabPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(pageAdapter);
tabLayout.setupWithViewPager(viewPager);
} // protected void onCreate
} // public class MainActivity
TabPagerAdapter has static final intances of the fragments
public class TabPagerAdapter extends FragmentPagerAdapter {
static final Fragment tabs[] = {new DashboardFragment(),
new Fragment2(),
new ExpensesFragment(),
new Fragment4()
};
public TabPagerAdapter(#NonNull FragmentManager fm) {
super(fm, FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
} // public TabPagerAdapter
#NonNull
#Override
public Fragment getItem(int position) {
if (position<tabs.length)
return tabs[position];
else
return null;
} // public Fragment getItem
#Override
public int getCount() {
return this.tabs.length;
} // public int getCount
} // class TabPagerAdapter
General fragment template for dashboard, fragment2, and fragment4
public class DashboardFragment extends Fragment {
public DashboardFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
} // onCreate
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_dashboard, container, false);
}
}
This is the code for the fragment with the dual pane. Look that it uses the OnItemSelected implementation of fragments communications.
This fragment loads another fragment with the recyclerview.
public class ExpensesFragment extends Fragment
implements IOnItemSelected {
#Override
public void onAccountSelected(Account item) {
System.out.println("Clicking on " + item.getTitle() + ", and isTwoPane=" + isTwoPane);
} // public void onAccountSelected
public static final String TAG="Expenses Fragment";
private boolean isTwoPane = false; // Let's assume we're on a phone
private FragmentManager fragmentManager;
private View fragmentView = null;
public ExpensesFragment() {
// Required empty public constructor
} // ExpensesFragment()
public static final ExpensesListFragment lListFragment = new ExpensesListFragment();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
} // onCreate
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
fragmentView = inflater.inflate(R.layout.fragment_expenses, container, false);
isTwoPane = fragmentView.findViewById(R.id.expensesDetailContainer) != null;
fragmentManager = getChildFragmentManager();
if (savedInstanceState==null) {
if ( !lListFragment.isAdded() ) {
fragmentManager.
beginTransaction().
add(R.id.expensesListContainer,lListFragment).
commit();
} // if ( !lListFragment.isAdded() )
} // if (savedInstanceState==null)
if ( isTwoPane ) {
fragmentManager.
beginTransaction().
replace(R.id.expensesDetailContainer,new EmptyFragment()).
commit();
} // if ( isTwoPane )
return fragmentView;
} // onCreateView
} // ExpensesFragment
And this is the fragment with the recyclerview:
public class ExpensesListFragment extends Fragment {
private IOnItemSelected mCallback;
private RecyclerView rv;
private RecyclerView.LayoutManager rvlm;
private RecyclerAdapterAccounts rva;
public ExpensesListFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mCallback = (IOnItemSelected)getParentFragment();
} // onCreate
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View fragmentView = inflater.inflate(R.layout.fragment_expenses_list, container, false);
if ( isVisible() ) return fragmentView;
FragmentManager fragmentManager = getChildFragmentManager();
// Setting the recyclerview environment
rv = fragmentView.findViewById(R.id.expensesRV); // recycler view
rvlm = new LinearLayoutManager(getActivity());
rv.setLayoutManager(rvlm);
rva = new RecyclerAdapterAccounts();
rva.setCallBackFunction(mCallback);
rv.setAdapter(rva);
// Setting the floating action button and snackbar
FloatingActionButton fab = fragmentView.findViewById(R.id.fabAdd);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Load a Create Item frag", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
return fragmentView;
} // onCreateView
} // public class ExpensesListFragment
The RecyclerAdapterAccounts creates a generic set of data:
public class RecyclerAdapterAccounts extends
RecyclerView.Adapter<RecyclerAdapterAccounts.ViewHolderAccounts> {
private IOnItemSelected callBackFunction;
public IOnItemSelected getCallBackFunction() {return callBackFunction;}
public void setCallBackFunction(IOnItemSelected callBackFunction) {this.callBackFunction = callBackFunction;}
class ViewHolderAccounts extends RecyclerView.ViewHolder {
ImageView icon, isRepeating, isAlert;
TextView title, total;
public Account getAccount() {return account;}
public void setAccount(Account account) {this.account = account;}
Account account;
public ViewHolderAccounts(View itemView) {
super(itemView);
icon = itemView.findViewById(R.id.list_item_ico_account);
isRepeating = itemView.findViewById(R.id.list_item_isrepeating);
isAlert = itemView.findViewById(R.id.list_item_isalert);
title = itemView.findViewById(R.id.list_item_title_account);
total = itemView.findViewById(R.id.list_item_desc_account);
account = null; // The account needs to be set using the setter/getter method
} // ViewHolderAccounts
} // class ViewHolderAccounts
List<Account> accts = new ArrayList<Account>();
ViewGroup parent;
#NonNull
#Override
public ViewHolderAccounts onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_account,parent,false);
this.parent = parent;
ViewHolderAccounts vh = new ViewHolderAccounts(v);
return vh;
} // onCreateViewHolder
#Override
public void onBindViewHolder(#NonNull ViewHolderAccounts holder, int position) {
// Look into the list the item with id=position
Optional<Account> la = accts.stream()
.filter(ac->ac.getId()==(long)position)
.findFirst();
if ( la.isPresent() ) {
int res = parent.getResources().getIdentifier(la.get().getIcon(), "drawable", "com.almonisolutions.elgddt");
holder.icon.setImageResource(res);
holder.isRepeating.setImageResource(R.drawable.automatic);
holder.isAlert.setImageResource(R.drawable.notifications);
holder.title.setText(la.get().getTitle());
holder.total.setText(la.get().getDescription());
holder.setAccount(la.get());
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (holder.getAccount() != null) {
callBackFunction.onAccountSelected(holder.getAccount());
} // if (account != null)
} // public void onClick
});
} // if
} // onBindViewHolder
#Override
public int getItemCount() {
return accts.size();
} // getItemCount
RecyclerAdapterAccounts() {
super();
for(int i=0;i<16;i++) {
Account la = new Account();
la.setId((long) i);
la.setTitle("The item number " + i);
la.setDescription("$" + (1000*i));
switch(i%3) {
case 0: la.setIcon("imaged"); break;
case 1: la.setIcon("person_old"); break;
case 2: la.setIcon("pet"); break;
default: la.setIcon("add");
} // switch
accts.add(la);
} // for
} // RecyclerAdapterAccounts
} // class RecyclerAdapterAccounts
At first, In the ExpensesFragment I was getting an Exception that throw the message "Fragment already added". When I changed the ExpensesListFragment to static final, that error was gone.
Again, to recreate the error, you need to run in portrait mode, move through the tabs. Finish on anyone but the first one. Them rotate the device. Tap on the first tab. Then tap on the 3rd one, the one with the recyclerview. Swipe through the list and you will see it is double.
Any help will be appreciated.
Thanks in advance!!!
So I found the answer. ADM (see comment above) sent me to a previous article where part of the solution was to extend ViewPager and override instantiateItem. But I did not want to extend ViewPager.
However, in the same article was another link to this other article where there was the following explanation:
Blockquote By default, [FragmentPagerAdapter] will only preload one Fragment in front and behind the current position (although it does not destroy them unless you are using FragmentStatePagerAdapter).
So, I made TabPagerAdapter extend FragmentStatePagerAdapter instead of FragmentPageAdapter... and that was it!!
Thanks ADM for pointing to the right series of articles.
Related
My app have a fragmentActivity with tabBar which control over the view pager and contain 3 fragments ,when i update my class User in fragmentB,i need to display him in fragmentC.
my question is how to refresh fragmentC every time when i add new User.
before i wrote this question i tried all the solution from this questions:
1.Update ViewPager dynamically?
2.refresh fragment at reload
3.Update Fragment from ViewPager
4.ViewPager PagerAdapter not updating the View
5.How to update fragment content from activity (viewpager)?
here is my code
FragmentActivity:
public class MainActivityTab extends FragmentActivity {
public SectionsPagerAdapter mSectionsPagerAdapter;
public ViewPager mViewPager;
public static MainActivityTab instance = null;
public static MainActivityTab getInstance(){
return instance;
}
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_tab);
getWindow().setStatusBarColor(Color.rgb(191,76,12));
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
final TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.getTabAt(0).setIcon(R.drawable.icon_A);
tabLayout.getTabAt(1).setIcon(R.drawable.icon_B);
tabLayout.getTabAt(2).setIcon(R.drawable.icon_C);
mViewPager.setCurrentItem(1,false);
}
FragmentStatePagerAdapter:
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position){
case 0:
return FragmentA.newInstance();
case 1:
return FragmentA.newInstance();
case 2:
return FragmentC.newInstance();
default:
return null;
}
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
return null;
}
}
FragmentB:
public class FragmentB extends Fragment {
EditText name;
EditText age;
Button btnSave;
public static FragmentB newInstance() {
FragmentB fragment = new FragmentB();
return fragment;
}
public FragmentB() {}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_new2, container, false);
name = (EditText) rootView.findViewById(R.id.name);
age = (EditText) rootView.findViewById(R.id.age);
btnSave = (Button) rootView.findViewById(R.id.btnSave);
btnSave.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
UserManager.getInstance().creteUser(name.getText().toString(),age.getText().toString());
}
});
return rootView;
}
}
FragmentC:
public class FragmentC extends Fragment {
TextView nameTxt;
TextView ageTxt;
public static FragmentC newInstance(){
FragmentC instance = new FragmentC();
return instance;
}
public FragmentC(){
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_new3, container, false);
nameTxt = (TextView) rootView.findViewById(R.id.nameTxt);
ageTxt = (TextView) rootView.findViewById(R.id.ageTxt);
showUser();
return rootView;
}
public void showUser(){
if(UserManager.getInstance().getUser().getName()!=null){
nameTxt.setText(UserManager.getInstance().getUser().getName().toString());
ageTxt.setText(UserManager.getInstance().getUser().getAge().toString());
}
}
}
You could create a callback like:
public interface UserChangedCallback{
void onUserChanged();
}
and implement this callback on every view/fragment where you want to access the user:
#Override
public void onUserChanged() {
adapter.notifyDataSetChanged();
// or if you don't have an adapter refresh your textfields or whatever you want
}
Register the callback on the usermanager via UserManager.getInstance().registerCallback(this). Internally the usermanager have to add the callback to an internal list.
Create a private function inside your usermanager:
private void notifyCallbacks() {
for(UserChangedCallback callback : registeredCallbacks) {
callback.onUserChanged();
}
}
If you add/modify/delete a user you always have to call this function at the end. For example:
public void addUser(User user) {
users.add(user);
notifiCallbacks();
}
Now every view will be notified and refreshed.
Important!
Don't forget to unregister the callback from the usermanager on onDestroy() to avoid memory leaks.
Found solution:
i used in the method onPageSelected,when position is 2 my fragment detach and afterwards attach the fragment.
working perfectly!
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
if(position==2){
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction().add(R.id.fragmant_new3, FragmentC.newInstance());
fragmentTransaction.detach(FragmentC.newInstance());
fragmentTransaction.attach(FragmentC.newInstance());
fragmentTransaction.commit();
}
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
I am using view pager in activity and the sequence is - when I click the next button in first page, it should go to the second page. If I click the button in second page, it should go to third and so on. But my current app is behaving weird, i.e, When I click next button in second page, it goes to fourth page. Once again when I click first button in first page, it jumps to third page and so on..
Here is code.
public class ViewPagerActivity extends AppCompatActivity {
private ViewPager pager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager_act);
setViewPager();
/*pager.setPageTransformer(true, new ZoomPageTransformer());
pager.setAdapter(new MyViewPagerAdapter(getSupportFragmentManager()));
pager.post(new Runnable() {
#Override
public void run() {
pager.setCurrentItem(position); //don't know how to use this from fragment
}
});*/
}
private void setViewPager() {
pager = (ViewPager) findViewById(R.id.viewPager);
FragmentManager fm = getSupportFragmentManager();
ViewPagerAdapter adapter = new ViewPagerAdapter(fm);
pager.setAdapter(adapter);
}
public void setCurrentItem(int selectedPosition) {
pager.setCurrentItem(selectedPosition, true);
}
private class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager supportFragmentManager) {
super(supportFragmentManager);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return FirstPager.newInstance();
case 1:
return SecondPager.newInstance();
case 2:
return ThirdPager.newInstance();
case 3:
return FourthPager.newInstance();
case 4:
return FifthPager.newInstance();
case 5:
return SixthPager.newInstance();
default:
return null;
}
}
#Override
public int getCount() {
return 6;
}
}
FirstPager:
public class FirstPager extends Fragment {
private ImageView slideArrow;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.first_pager, container, false);
return v;
}
public static FirstPager newInstance() {
FirstPager fragment = new FirstPager ();
return fragment;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initUI();
}
private void initUI() {
slideArrow = (ImageView) getActivity().findViewById(R.id.next_arrow);
slideArrow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((ViewPagerActivity)getActivity()).setCurrentItem (1);
}
});
}
}
Similarly in other fragments, I gave currentItem as 2,3,4,5 and 6. But it’s position behavior is not correct.
I referred some post but how in my case, how I will apply for a method to pass from fragment to make the position to work correctly?
I think the best approach would be this:
viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
slideArrow = (ImageView) getActivity().findViewById(R.id.next_arrow);
Are you sure, you're calling this correctly? You're not.
You're calling findViewById of the arrow inside your activity. A ViewPager works by loading this page, and pre-loading next and previous pages for smooth swipe. And when you click the button on your 1st page, the last loaded page's (in your case 2nd page's) button click event gets called.
You must use the arrow button in each of your fragments
You can do something like this:
public class FirstPager extends Fragment {
private ImageView slideArrow;
View v;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
v = inflater.inflate(R.layout.first_pager, container, false);
return v;
}
public static FirstPager newInstance() {
FirstPager fragment = new FirstPager ();
return fragment;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initUI();
}
private void initUI() {
slideArrow = (ImageView) v.findViewById(R.id.next_arrow); // Note the difference in this line.
slideArrow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((ViewPagerActivity)getActivity()).setCurrentItem (1);
}
});
}
}
You can do two things here:
Firstly,Your viewpager has a override method onPageSelected() which return the select page positon. using this poistion element get the view and bind your button there and write listener there itself and write viewpager.setCurrentItem(i++); //if i is ur current position,but be sure to check if it is the last item.
secondly,you hold the position of the current fragment and
((ViewPagerActivity)getActivity()).setCurrentItem (next_frag_pos);
This code try working perfect.
public class ViewPagerActivity extends FragmentActivity {
private ViewPager pager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager_act);
setViewPager();
/*pager.setPageTransformer(true, new ZoomPageTransformer());
pager.setAdapter(new MyViewPagerAdapter(getSupportFragmentManager()));
pager.post(new Runnable() {
#Override
public void run() {
pager.setCurrentItem(position); //don't know how to use this from fragment
}
});*/
}
private void setViewPager() {
pager = (ViewPager) findViewById(R.id.viewPager);
FragmentManager fm = getSupportFragmentManager();
ViewPagerAdapter adapter = new ViewPagerAdapter(fm);
pager.setAdapter(adapter);
}
public void setCurrentItem(int selectedPosition) {
pager.setCurrentItem(selectedPosition, true);
}
private class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager supportFragmentManager) {
super(supportFragmentManager);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new FirstPager();
case 1:
return new SecondPager();
case 2:
return new ThirdPager();
case 3:
return new FourthPager();
case 4:
return new FifthPager();
case 5:
return new SixthPager();
default:
return null;
}
}
#Override
public int getCount() {
return 6;
}
}
}
I have 4 Fragments in a ViewPager that is integrated with a TabLayout. Each of those Fragments holds a RecyclerView because I'm displaying an unknown amount of list items. The items are loaded by date, so I have two buttons that let you change days, and then the appropriate data in the list items is loaded based on the date that is set. The buttons are part of the outer activity.
Everything so far works perfectly BUT once I rotate the device the fragments don't load anything. Nothing is displayed inside the Fragments. The views in the outer activity are displayed fine though. The weird thing is that if I touch one of the buttons that changes the date, the Fragments are loaded and the data is displayed correctly. But I need everything to be displayed immediately after rotation not just when I click one of those buttons. Here is my code:
public class MainActivity extends AppCompatActivity implements DatePickerFragment.DateDialogInterface
{
private final static String COLOR_CONTROL_CHOSEN = "color_control_chosen";
private static final String DIALOG_DATE = "dialog_date";
private static final String TAG = "MainActivity";
private static final String SET_LOCATION = "set_location";
public static final String LEAGUE_POSITION = "league_position";
private Toolbar mToolbar;
private ViewPager mViewPager;
private TabLayout mTabLayout;
private ImageButton mPrevDateButton, mNextDateButton;
private TextView mDateTextView, mLeagueTextView;
private String mTodaysDate;
private Date mLastSelectedDate, mTodaysDateObj;
private ProgressBar mProgressBar;
private FragmentPagerAdapter mAdapterViewPager;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mToolbar = (Toolbar) findViewById(R.id.outnix_toolbar);
mViewPager = (ViewPager) findViewById(R.id.main_activity_view_pager);
mTabLayout = (TabLayout) findViewById(R.id.main_activity_tab_layout);
mDateTextView = (TextView) findViewById(R.id.display_date_text_view);
mLeagueTextView = (TextView) findViewById(R.id.league_title_header);
mPrevDateButton = (ImageButton) findViewById(R.id.previous_date_button);
mNextDateButton = (ImageButton) findViewById(R.id.next_date_button);
mProgressBar = (ProgressBar) findViewById(R.id.loading_circle);
mProgressBar.setVisibility(View.GONE);
setTodaysDate();
mDateTextView.setText("Today");
setSupportActionBar(mToolbar);
assert getSupportActionBar() != null;
getSupportActionBar().setDisplayShowTitleEnabled(false);
NavDrawerFragment navDrawerFrag = (NavDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_nav_drawer);
navDrawerFrag.setUp((DrawerLayout) findViewById(R.id.nav_drawer), mToolbar);
setUpViewPagerAdapterOnCreate();
mTabLayout.setupWithViewPager(mViewPager);
mDateTextView.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
FragmentManager fm = getSupportFragmentManager();
DatePickerFragment dialog = new DatePickerFragment();
Bundle args = new Bundle();
args.putSerializable("ARG_DATE", mLastSelectedDate);
dialog.setArguments(args);
dialog.show(fm, DIALOG_DATE);
}
});
THESE TWO LISTENERS ARE WHAT DISPLAY THE DATA AFTER A ROTATION CHANGE
//////////////////////////////////////////////////////////////////
mPrevDateButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
mProgressBar.setVisibility(View.VISIBLE);
updateDate(-1);
setupViewPagerAdapter(getViewPagerPos());
}
});
mNextDateButton.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
mProgressBar.setVisibility(View.VISIBLE);
updateDate(1);
setupViewPagerAdapter(getViewPagerPos());
}
});
}
////////////////////////////////////////////////////////////////////
/* #Override
protected void onResume()
{
super.onResume();
setupViewPagerAdapter(getViewPagerPos());
}*/
private void setUpViewPagerAdapterOnCreate() //only called when opened from LauncherActivity
{
setupViewPagerAdapter(0);
int touchColorPixel = getIntent().getIntExtra(COLOR_CONTROL_CHOSEN, ContextCompat.getColor(this, R.color.blue));
if(touchColorPixel == ContextCompat.getColor(this, R.color.orange))
mViewPager.setCurrentItem(0);
else if(touchColorPixel == ContextCompat.getColor(this, R.color.blue))
mViewPager.setCurrentItem(1);
else
mViewPager.setCurrentItem(3);
}
private void setupViewPagerAdapter(int currentPos)
{
mAdapterViewPager = new MainPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mAdapterViewPager);
mViewPager.setOffscreenPageLimit(4);
mViewPager.setCurrentItem(currentPos);
}
#Override
protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
outState.putSerializable(DIALOG_DATE, mLastSelectedDate); //save the last date selected (or last date displayed) on rotation change.
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState);
setDateFromDialog((Date) savedInstanceState.getSerializable(DIALOG_DATE)); //restore the last date selected to the new rotation change
}
public ProgressBar getProgressBar()
{
return mProgressBar;
}
#Override
public void setDateFromDialog(Date date)
{
String newDate = getFormattedDate(date);
updateTodaysDate();
mLastSelectedDate = date;
setupViewPagerAdapter(getViewPagerPos());
if(newDate.equals(mTodaysDate))
mDateTextView.setText("Today");
else
mDateTextView.setText(newDate);
}
private int getViewPagerPos()
{
return mViewPager.getCurrentItem();
}
}
The 2 buttons mPrevDateButton and mNextDateButtonare the buttons that when clicked "fix" the problem. Inside their click listeners, the updateDate() method is only doing stuff related to a TextView object and is why I didn't include the definitions (I'm trying to keep the post as short as possible). So I know for sure it has something to do with my setupViewPagerAdapter() method. I've tried adding this method in onCreate() and onResume() but the Fragments still stay blank.
Here is my ViewPager adapter code:
public class MainPagerAdapter extends FragmentPagerAdapter
{
private final String[] mFragmentTitleList = {"My Games", "All Games", "All Places", "My Places"}; //tab title names
private final static int NUM_FRAGMENTS = 4;
public MainPagerAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public Fragment getItem(int position)
{
switch(position)
{
case 0:
return MyGamesFragment.newInstance();
case 1:
return AllGamesFragment.newInstance();
case 2:
return AllPlacesFragment.newInstance();
case 3:
return MyPlacesFragment.newInstance();
default:
return null;
}
}
#Override
public int getCount()
{
return NUM_FRAGMENTS;
}
#Override
public CharSequence getPageTitle(int position)
{
return mFragmentTitleList[position];
}
}
Here is one of the 4 fragments. They pretty much all have similar design.
public class AllGamesFragment extends Fragment
{
private SwipeRefreshLayout mSwipeRefreshLayout;
private RecyclerView mAllGamesRecyclerView;
private GameAdapter mGameAdapter;
private List<Game> mGameList = new ArrayList<>();
private MainActivity mMainActivity; //keeps a reference to MainActivity to access public methods
public static AllGamesFragment newInstance()
{
return new AllGamesFragment();
}
#Override
public void onAttach(Context context)
{
super.onAttach(context);
mMainActivity = (MainActivity) context;
}
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setRetainInstance(true);
mMainActivity.getProgressBar().setVisibility(View.VISIBLE);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.recycler_view_all_games, container, false);
mAllGamesRecyclerView = (RecyclerView) view.findViewById(R.id.all_games_recycler_view);
mAllGamesRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mSwipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_refresh);
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener()
{
#Override
public void onRefresh()
{
getGamesData();
mSwipeRefreshLayout.setRefreshing(false);
}
});
return view;
}
#Override
public void onResume()
{
super.onResume();
getGamesData();
}
private void setupAdapter()
{
if(isAdded())
{
mGameAdapter = new GameAdapter(mGameList);
mAllGamesRecyclerView.setAdapter(mGameAdapter);
}
}
private void getGamesData()
{
new GetDataTask(mMainActivity.getLastSelectedDate()).execute();
}
private class GetDataTask extends Scraper.GameDataTask
{
GetDataTask(Date date)
{
super(date, getActivity());
}
#Override
protected void onPostExecute(List<Game> games)
{
mGameList = games;
setupAdapter();
mMainActivity.getProgressBar().setVisibility(View.GONE);
}
}
private class GameAdapter extends RecyclerView.Adapter<GameHolder>
{
private List<Game> mGames;
public GameAdapter(List<Game> games)
{
mGames = games;
}
#Override
public GameHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
LayoutInflater inflater = LayoutInflater.from(getActivity());
View view = inflater.inflate(R.layout.list_game_item, parent, false);
return new GameHolder(view, getActivity());
}
#Override
public void onBindViewHolder(GameHolder holder, int position)
{
holder.bindGameData(mGames.get(position));
}
#Override
public int getItemCount()
{
return mGames.size();
}
}
I've looked at so many posts on here, changed my code many times and I still can't get it to work. I'm just baffled that it "fixes" when I click one of the date buttons. If you would like me to post more code of something let me know. Sorry for the long post but I feel the context is needed. I really appreciate any help!
I figured it out! I had to switch to a FragmentStatePagerAdapter rather than use a FragmentPagerAdapter. I believe it has something to do with the Fragments being destroyed and recreated again.
I also read that another way would be to wrap the ViewPager in a Fragment and when you create its adapter you use getChildFragmentManager() rather than getSupportFragmentManager() like this:
mAdapterViewPager = new MyPagerAdapter(getChildFragmentManager());
I didn't want to have to add an entire Fragment around my ViewPager just to fix this issue so I switched to using FragmentStatePagerAdapter and it worked! Hope this helps someone else out there.
Making viewPager adapter extends FragmentStatePagerAdapter and not FragmentPagerAdapter should solve the problem.
I'm building an Android application using a FragmentStatePagerAdapter for tabbed navigation and dynamic content in each tab. Each tab has Fragment with content which is to be replaced upon user input (for example, the first tab has a Fragment containing a list of books, and upon clicking, you can access detailed information of the book, which is displayed using another Fragment
Problem: I haven't find a way of correctly handling the onBack events nor the BackStack, so when I'm reviewing any book's details, I can easily go back pressing the back button - I mean, popping the last state from the BackStack.
What I suspect: The way I'm switching Fragment objects may not the the best one, but except for the back button issue, it is working just as I want. I suspect some problem between the FragmentStatePagerAdapter's adapter, and the FragmentManager's own collection of Fragments; probably this is something with an easy solution I didn't see.
Unaswered question (not very detailed though): Adding Fragment to BackStack using FragmentStatePagerAdapter
The code:
// MAIN ACTIVITY, Just this simple.
public class MainActivity extends FragmentActivity {
public static final String TAG = "MainActivity";
// Whether the Log Fragment is currently shown
private boolean mLogShown;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
MainTabSliderFragment fragment = new MainTabSliderFragment();
transaction.replace(R.id.sample_content_fragment, fragment);
transaction.commit();
}
}
}
.
// THE SLIDE TAB FRAGMENT, which becomes the parent view of the tabs.
public class MainTabSliderFragment extends Fragment {
static final String LOG_TAG = MainTabSliderFragment.class.getSimpleName();
private SlidingTabLayout mSlidingTabLayout;
private ViewPager mViewPager;
private CustomFragmentStatePageAdapter cfspAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_sample, container, false);
return root;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
mViewPager = (ViewPager) view.findViewById(R.id.viewpager);
cfspAdapter = new CustomFragmentStatePageAdapter(getFragmentManager());
List<String> pageTitles = new ArrayList<>();
pageTitles.add(getString(R.string.page_one));
pageTitles.add(getString(R.string.page_two));
pageTitles.add(getString(R.string.page_three));
List<Fragment> pageFragments = new ArrayList<>();
final BookListPageFragment pageOne = BookListPageFragment.newInstance(new CustomFragmentStatePageAdapter.SwitchFragmentListener() {
#Override
public void onSwitchFragments(Class<? extends Fragment> clazz, Map<String, String> ... args) {
cfspAdapter.switchFragment(CustomFragmentStatePageAdapter.PagePosition.POSITION_PAGE_ONE, clazz, this, args);
}
});
CustomerPageFragment pageTwo = CustomerPageFragment.newInstance(...);
ForumPageFragment pageThree = ForumPageFragment.newInstance(...);
pageFragments.add(pageOne);
pageFragments.add(pageTwo);
pageFragments.add(pageThree);
cfspAdapter.addFragments(pageFragments, pageTitles);
mViewPager.setAdapter(cfspAdapter);
mSlidingTabLayout = (SlidingTabLayout) view.findViewById(R.id.sliding_tabs);
mSlidingTabLayout.setViewPager(mViewPager);
}
}
.
// THE FIRST TAB, In its initial state (the initial fragment).
public class BookListPageFragment extends Fragment {
private static final String TAG = BookListPageFragment.class.getSimpleName();
private BookListAdapter bAdapter;
private static CustomFragmentStatePageAdapter.SwitchFragmentListener switchFragmentListener;
public static BookListPageFragment newInstance(CustomFragmentStatePageAdapter.SwitchFragmentListener _switchFragmentListener) {
switchFragmentListener = _switchFragmentListener;
BookListPageFragment f = new BookListPageFragment();
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.page_one_booklist, container, false);
final ListView lv = (ListView) v.findViewById(R.id.list);
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
BookRowData bRow = (BookRowData) lv.getItemAtPosition(position);
Log.i(TAG, "Clicked on book " + bRow.getBookId());
Map<String, String> param = new HashMap<>();
param.put("book_id", Long.toString(bRow.getBookId()));
switchFragmentListener.onSwitchFragments(ReviewBookPageFragment.class, new Map[]{param});
}
});
initializeTestList(v, lv); // Just add some books to the list.
return v;
}
.
// THE PAGE ADAPTER, used for handling tab's Fragment switching.
public class CustomFragmentStatePageAdapter extends FragmentStatePagerAdapter {
private final static String TAG = FragmentStatePagerAdapter.class.getSimpleName();
private FragmentManager fragmentManager;
private List<Fragment> fragmentList = new ArrayList<>();
private List<String> tabTitleList = new ArrayList<>();
public CustomFragmentStatePageAdapter(FragmentManager fm) {
super(fm);
fragmentManager = fm;
}
public void addFragments(List<Fragment> fragments, List<String> titles) {
fragmentList.clear();
tabTitleList.clear();
fragmentList.addAll(fragments);
tabTitleList.addAll(titles);
notifyDataSetChanged();
}
#Override
public int getItemPosition(Object object) {
if (fragmentList.contains(object)) {
return POSITION_UNCHANGED;
}
return POSITION_NONE;
}
#Override
public Fragment getItem(int item) {
if (item >= fragmentList.size()) {
return null;
}
return fragmentList.get(item);
}
#Override
public int getCount() {
return fragmentList.size();
}
#Override
public CharSequence getPageTitle(int position) {
return tabTitleList.get(position);
}
/**
* Switching pages
*
* #param newFragment
*/
public void switchFragment(final PagePosition position, Class<? extends Fragment> newFragment, SwitchFragmentListener sfListener, Map<String, String> ... args) {
final Fragment old = fragmentList.get(position.getPagePosition());
fragmentManager.beginTransaction().remove(old).commit(); //FIRST VERSION: IF HITTING BACK, IT EXITS APP AT ONCE.
//fragmentManager.beginTransaction().addToBackStack("page_one").remove(old).commit(); //SECOND VERSION: NOW I NEED TO HIT BACK TWICE TO EXIT, BUT THE VIEW DOESN'T CHANGE AFTER HITTING THE FIRST TIME.
try {
Fragment f = (Fragment) newFragment.asSubclass(Fragment.class).getMethod("newInstance", SwitchFragmentListener.class, Map[].class).invoke(newFragment, new Object[]{sfListener, args});
fragmentList.set(position.getPagePosition(), f);
} catch (IllegalAccessException iae) {
Log.e(TAG, "Fragment class access exception");
} catch (NoSuchMethodException e) {
Log.e(TAG, "Fragment instantiation exception (reflection)");
} catch (InvocationTargetException e) {
Log.e(TAG, "Fragment instantiation exception (reflection: no public constructor)");
}
notifyDataSetChanged();
}
public interface SwitchFragmentListener {
void onSwitchFragments(Class<? extends Fragment> clazz, Map<String, String> ... args);
}
public enum PagePosition {
POSITION_PAGE_ONE (0),
POSITION_PAGE_TWO (1),
POSITION_PAGE_THREE (2);
private final int position;
PagePosition(int position) {
this.position = position;
}
public int getPagePosition() {
return this.position;
}
}
}
.
// AND FINALLY THE FRAGMENT I WANT TO GO BACK FROM; this is the book review Fragment, which is displayed also in the first tab when clicking on a book from the list. Second and third tabs are ommitted.
public class ReviewBookPageFragment extends Fragment {
private static final String TAG = ReviewBookPageFragment.class.getSimpleName();
private CommentsListAdapter cAdapter;
private Long bookId;
private static CustomFragmentStatePageAdapter.SwitchFragmentListener switchFragmentListener;
public static ReviewBookPageFragment newInstance() {
ReviewBookPageFragment f = new ReviewBookPageFragment();
return f;
}
public static ReviewBookPageFragment newInstance(CustomFragmentStatePageAdapter.SwitchFragmentListener _sfListener, Map<String, String> ... args) {
switchFragmentListener = _sfListener;
Bundle b = BundlePacker.packMaps(args); // Custom util class for packing the params into a bundle.
ReviewBookPageFragment f = new ReviewBookPageFragment();
f.setArguments(b);
return f;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.page_review_book, container, false);
Bundle bookIdBundle = this.getArguments();
Long bId = Long.parseLong(bookIdBundle.getString("book_id"));
Log.i(TAG, "Book ID: " + bId);
initializeTestList(v); // Just fill the book's reviews with test data.
return v;
}
}
So, that's the bunch of code. The idea, as a summary, is to switch from the books list view (shown on tab one), to the book's reviews when tapping on any book from the list; the reviews are also shown on the first tab, and I want to go back to the books list when pressing back. Currently, it closes the application hitting back ONCE, and if I add the transaction to the backstack (see my CustomFragmentStatePageAdapter), TWICE (but the view doesn't change after hitting back the first time.
Any help with the issue will be greatly appreciated.
For fixing the popback issue you can use this code in your activity class,
#Override
public void onBackPressed() {
// if there is a fragment and the back stack of this fragment is not empty,
// then emulate 'onBackPressed' behaviour, because in default, it is not working
FragmentManager fm = getSupportFragmentManager();
for (Fragment frag : fm.getFragments()) {
if (frag.isVisible()) {
FragmentManager childFm = frag.getChildFragmentManager();
if (childFm.getBackStackEntryCount() > 0) {
childFm.popBackStack();
return;
}
}
}
super.onBackPressed();
}
I did somethink like this:
private View _view;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if(_view==null){
_view = inflater.inflate(R.layout.page_review_book, container, false);
// your_code
}
return _view;
}
I have a fragment activity that uses a ViewPager to display a set of fragments. On the fragment activity I have a button that when clicked, it sends a message to the current fragment to refresh its contents. Everything works ok (activity / current fragment communication) except the fact that I cannot refresh the fragment's view. Accessing the current view by getView() does not work as this function returns null; it seems that after the fragment is created (on ViewCreated is called) getView gets destroyed. Am I missing something here? How to I cause a fragment to redraw its contents programmatically? It seems that the only way this works is when the fragment is created from the parent activity. Do I have to remove and re-add the fragment again to do this?
Here is the code:
The main activity:
public class MainActivity extends FragmentActivity {
private MyAdapter mAdapter;
private static ViewPager mPager;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupViewPager();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
#Override
public boolean onPrepareOptionsMenu(Menu menu) {
return super.onPrepareOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_test:
updateFragment();
return true;
default: return true;
}
}
private void updateFragment() {
for (int i=0; i< mAdapter.getCount(); i++) {
SampleFragment fragment = (SampleFragment) mAdapter.getItem(i);
fragment.update();
}
}
private void setupViewPager() {
try {
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(this.mAdapter);
} catch (Exception e) {
e.printStackTrace();
}
}
public class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
SampleFragment fragment = new SampleFragment(position);
return fragment;
}
#Override
public int getCount() {
return 5;
}
}
}
and the fragment class:
public class SampleFragment extends Fragment{
private int myPosition = -1;
public SampleFragment(int position) {
this.myPosition = position;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment, container, false);
update(view, "Updated from onCreateView");
return view;
}
#Override
public void onActivityCreated(Bundle bundle) {
super.onActivityCreated(bundle);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
view.findViewById(R.id.textTitle).setOnClickListener(myClickListener);
}
private OnClickListener myClickListener = new OnClickListener() {
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.textTitle:
break;
}
}
};
public void update() {
update(getView(), "Updated from main");
}
private void update(View view, String subtitleText) {
TextView title = (TextView) view.findViewById(R.id.textTitle);
TextView subtitle = (TextView) view.findViewById(R.id.textSubtitle);
title.setText("Fragment " + myPosition);
subtitle.setText(subtitleText);
}
}
The error happens on view.FindViewById (view is null) when called from the menu item in the main activity.
You can take a look at this article which explains how to keep references to the fragments in your ViewPager.
There are two methods described on the page. The first one involves setting a tag when you add the fragment using the FragmentManager. Then you can retrieve the fragment using findFragmentByTag(). However, I did not see how to make this work using FragmentPagerAdapter or FragmentStatePagerAdapter, since these implementations add the fragments for you. If you are using your own custom PagerAdapter, this may work for you.
The other method, which does work for FragmentPagerAdapter or FragmentStatePagerAdapter, involves keeping a map of all your fragments, updating inside your getItem() and destroyItem() implementations. This method has worked for me.
Once you have a reference to the current fragment, you can just call a method in your fragment to refresh its view.