I write a ViewPager with some Fragments. In the Fragment, there are VideoView. At the beginning, the first VideoView will auto play, when the first VideoView finishes, I want change the page of VideoView, so I want call setCurrentItem in Fragment. Is this possible?
you can use eventbus notice viewpager to next page.
implement toNextPage func
void toNextPage() {
if (viewPager.getAdapter().getCount() >= viewPager.getCurrentItem() + 1) {
viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
} else {
Toast.makeText(this, "is end", Toast.LENGTH_SHORT).show();
}
}
As you've not mentioned the language you're using, I'm gonna answer it for both Java and Kotlin.
Java:
Create a function in your ViewPager's Activity as
public void changeViewPagerPostition(int position) {
viewPager.setCurrentItem(position);
}
And call this function it from Fragment with passing the postition parameter as
((YourActivity) getActivity()).changeViewPagerPostition(yourPostition);
//Remember first item is at 0th postition and so on.
You can also declare the ViewPager as public static in your Activity and can access the ViewPager directly in Fragment but this is not the preferred way.
Kotlin:
In kotlin, it's a bit easy I believe, although you can use exact same way mentioned for Java but I use this way as I also use ViewPager for more things:
Declare the ViewPager as global variable in your Activity as
lateinit var viewPager : ViewPager
Initialize in it onCreate() of the Activity as
viewPager = findViewById(R.id.viewPager)
And use it in fragment and pass your current postition as
(activity as YourActivity?)!!.setCurrentItem(yourPosition)
Now, the moment your video finishes, you can call any of these ways in your Fragment to change the currentItem of the ViewPager.
Related
Problem:
I am currently running into a problem where my app is trying to load too many fragments when it opens for the first time.
I have BottomNavigationView with ViewPager that loads 4 fragments - each one of the Fragment contains TabLayout with ViewPager to load at least 2 more fragments.
As you can imagine, that is a lot of UI rendering (10+ fragments) - especially when some of these fragments contain heavy components such as calendar, bar graphs, etc.
Currently proposed solution:
Control the UI loading when the fragment is required - so until the user goes to that fragment for the first time, there is no reason to load it.
It seems like it's definitely possible as many apps, including the Play Store, are doing it. Please see the example here
In the video example above - the UI component(s) are being loaded AFTER the navigation to the tab is completed. It even has an embedded loading symbol.
1) I am trying to figure out how to do exactly that - at what point would I know that this fragment UI need to be created vs it already is created?
2) Also, what is the fragment lifecycle callback where I would start the UI create process? onResume() means UI is visible to the user so loading the UI there will be laggy and delayed.
Hope this is clear enough.
EDIT:
I'm already using the FragmentStatePagerAdapter as ViewPager adapter. I noticed that the super(fm) method in the constructor is deprecated now:
ViewPagerAdapter(FragmentManager fm) {
super(fm); // this is deprecated
}
So I changed that to:
ViewPagerAdapter(FragmentManager fm) {
super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
}
BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT: Indicates that only the current fragment will be in the Lifecycle.State.RESUMED state. All other Fragments are capped at Lifecycle.State.STARTED.
This seems useful as the onResume() of the Fragment will only be called when the Fragment is visible to the user. Can I use this indication somehow to load the UI then?
The reason your app loads multiple Fragments at the startup is most probably, you're initializing them all at once. Instead, you can initialize them when you need them. Then use show\ hide to attach\ detach from window without re-inflating whole layout.
Simple explanation: You'll create your Fragment once user clicks on BottomNavigationView's item. On clicked item, you'll check if Fragment is not created and not added, then create it and add. If it's already created then use show() method to show already available Fragment and use hide() to hide all other fragments of BottomNavigationView.
As per your case show()/hide is better than add()/replace because as you said you don't want to re-inflate the Fragment when you want show them
public class MainActivity extends AppCompatActivity{
FragmentOne frg1;
FragmentTwo frg2;
#Override
public boolean onNavigationItemSelected(MenuItem item){
switch(item.getId()){
case R.id.fragment_one:
if (frg2 != null && frg2.isAdded(){
fragmentManager.beginTransaction().hide(frg2).commit();
}
if(frg1 != null && !frg1.isAdded){
frg1 = new FragmenOne();
fragmentManager.beginTransaction().add(R.id.container, frg1).commit();
}else if (frg1 != null && frg1.isAdded) {
fragmentManager.beginTransaction().show(frg1).commit();
}
return true;
case R.id.fragment_two:
// Reverse of what you did for FragmentOne
return true;
}
}
}
And for your ViewPager as you can see from the example you're referring to; PlayStore is using setOffscreenPageLimit. This will let you choose how many Views should be kept alive, otherwise will be destroyed and created from start passing through all lifecycle events of the Fragment (in case view is Fragment). In PlayStore app's case that's probably 4-5 that why it started loading again when you re-selected "editor's choice" tab. If you do the following only selected and neighboring (one in the right) Fragments will be alive other Fragments outside screen will be destroyed.
public class FragmentOne extends Fragment{
ViewPager viewPager;
#Override
public void onCreateView(){
viewPager = .... // Initialize
viewpAger.setOffscreenPageLimit(1); // This will keep only 2 Fragments "alive"
}
}
Answer to both questions
If you use show/hide you won't need to know when to inflate your view. It will be handled automatically and won't be laggy since it's just attaching/detaching views not inflating.
It depends upon how you initialize your fragment in your activity. May be you are initializing all your fragment in onCreate method of your activity instead of that you can initialize it when BottomNavigation item is selected like below :
Fragment one,two,three,four;
#Override
public boolean onNavigationItemSelected(MenuItem item){
Fragment fragment;
switch(item.getId()){
case R.id.menu_one:{
if(one==null)
one = Fragment()
fragment = one;
break;
}
case R.id.menu_two:{
if(two==null)
two = Fragment()
fragment = two;
break;
}
}
getFragmentManager().beginTransaction().replace(fragment).commit();
}
To decide how many page is load in you view pager at one time you can use :
setOffscreenPageLimit.
viewPager.setOffscreenPageLimit(number)
To get the resume and pause functionality on fragments you can take an example from this link.
Please try this.
i was worked with the same kind of the Application, There were multiple tabs and also Tabs have multiple inner tabs.
i was used the concept of ViewPager method, In which there is one method of onPageSelected() for that method we were getting the page position.
By the Use of this position we are checking the current Fragment and called their custom method that we created inside that fragment like onPageSelected() defined inside that fragment.
With this custom method onPageSelected() inside the Fragment we checked that weather the list are available or not if list have data then we are not making the call of Api otherwise we are calling the Api and loading that list.
I think you have same kind of requirement to follow if your Tabs have inner Tab or viewpager you can follow same concept inside of that so if your current fragment of viewpager method onpageSelected called at that time your viewpager fragment initialized.
you have to call just initialization like data binding or view initialization need to be called in onCreate() method and other list attachment and api call to be managed by the custom method onPageSelected that will be called based on ViewPager onPageSelected.
let me Know if you need any help for same.
You can try to have Fragments with FrameLayouts only in ViewPager. The actual Fragments could be added to FrameLayout in onResume() (after checking if this Fragment isn't already attached). It should work if BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT works as expected.
I would recommend you use BottomNavigationView.setOnNavigationItemSelectedListener to toggle between the fragment UI whenever it is needed.
navigationView.setOnNavigationItemSelectedListener(item -> {
switch(item.getItemId()) {
case R.id.item1:
// you can replace the code findFragmentById() with findFragmentByTag("dashboard");
// if you only have one framelayout to hold the fragment
fragment = getSupportFragmentManager().findFragmentById(R.id.fragment_container);
if (fragment == null) {
fragment = new ExampleFragment();
// if the fragment is identified by tag, add another
// argument to this method:
// replace(R.id.fragment_container, fragment, "dashboard")
getSupportFragmentManager().begintransaction()
.replace(R.id.fragment_container, fragment)
.commit();
}
break;
}
}
The idea is simple, when the user swipes or selects a different tab, the fragment that was visible is replaced by the new fragment.
Just load fragments one by one. Create the main fragment layout with many placeholders and stubs and then just load them in the order you like.
Use FragmentTransaction.replace() from the main fragment after it loads.
Have you tried the setUserVisibleHint() method of a fragment
override fun setUserVisibleHint(isVisibleToUser: Boolean) {
super.setUserVisibleHint(isVisibleToUser)
if(isVisibleToUser){
// Do you stuff here
}
}
This will only get called when a fragment is visible to the user
How about you maintain just one ViewPager? Sounds crazy? In that case, you just change the dataset of PagerAdapter when you switch between the bottom tabs. Let's see how you can accomplish this,
As you mentioned, you have 4 fragments, which are assigned to each individual tabs of the bottom navigation view. Each performs some redundant work i.e. holding a viewPager with tab layout and setting the same kind of adapters. So, if we can combine these 4 redundant tasks into one then we will be able to get rid of 4 fragments. And as there will be just one viewPager with one single adapter then we will be able to reduce the fragment loading count from ~10 to 2 if we set offScreenPageLimit to 1. Let's see some example,
activity.xml should look like
<LinearLayout>
<TabLayout />
<ViewPager />
<BottomNavigationView />
</LinearLayout>
It's optional but I would recommend to create a base PagerFragment abstract class with abstract method getTabTitle()
public abstract class PagerFragment extends Fragment {
public abstract String getTabTitle();
}
Now it's time to make our PagerAdapter class
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public Map<Integer, List<PagerFragment>> map = ...; // If you are concerned about memory then I could recommend to store DataObject instead of PagerFragment and instantiate fragment on demand using that data.
public int currentTabId = R.id.first_bottom_tab_id;
private List<PagerFragment> getCurrentFragments() {
return map.get(currentTabId);
}
public void setCurrentTabId(int tabId) {
this.currentTabId = tabId;
}
public SectionsPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return getCurrentFragments().get(position);
}
#Override
public int getCount() {
return getCurrentFragments().size();
}
#Override
public int getItemPosition(#NonNull Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
return getCurrentFragments().get(position).getTabTitle();
}
}
And finally, in Activity
SectionsPagerAdapter pagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(pagerAdapter);
viewPager.setOffscreenPageLimit(1);
viewPagerTab.setViewPager(viewPager);
bottomNavigationView.setOnNavigationItemSelectedListener(menuItem -> {
pagerAdapter.setCurrentTabId(menuItem.getItemId())
pagerAdapter.notifyDataSetChanged();
viewPagerTab.setViewPager(viewPager);
}
This is the basic idea. You can mix some of your own ideas with it to make a wonderful result. Let me know if it is useful?
UPDATE
Answer to your questions,
I think with my solution you can achieve exactly the same behavior of the video as I already did it in a project. In my solution, if you set offset page limit to 1 then only adjacent fragment's is created in advance. So, fragment creation will be handled by adapter and viewpager you don't need to worry about it.
In my above solution, you should create UI in onCreateView().
I have a ViewPager and its child fragments are dynamic. I am using them in the same fragment class and I am changing the field's value dynamically. But when I changing the ViewPager position, It is not updating the fragment. I have to change the values instantly.
Thank you.
Declare refreshFragment method in your fragment class then
In ViewPagerAdapter class overwritte method
#Override
public int getItemPosition(#NonNull Object object) {
MyFragment f = (MyFragment ) object;
if (f != null) {
f.refreshFragment();
}
return super.getItemPosition(object);
}
When you call
viewPagerAdapter.notifyDataSetChanged();
it will call getItemPosition method in adapter class and update your fragment using refreshFragment method.
Android by default retains one page on both sides of the current page for optimised loading. Since you need the pages to refresh on every time, you need to use viewpager.setOffScreenPageLimit(0) to set all pages to be recreated every time they are viewed
I am using 4 fragments inside a ViewPager ,as ViewPager load the previous and next fragment in advance ,and no lifecycle method is called when navigating between fragments.
So is there any way to detect when Fragment is actually visible.
Thanks in Advance.
as per #Matt's answer setUserVisibleHint is deprecated
so here is alternative way for this.
#Override
public void setMenuVisibility(boolean isvisible) {
super.setMenuVisibility(isvisible);
if (isvisible){
Log.d("Viewpager", "fragment is visible ");
}else {
Log.d("Viewpager", "fragment is not visible ");
}
}
Of course. Assuming that viewPager is your instance of the ViewPager, use: viewPager.getCurrentItem().
Within your Fragment you can check if its instance is visible to the user like so:
#Override
public void setUserVisibleHint(boolean visible) {
super.setUserVisibleHint(visible);
if (visible) {
Log.i("Tag", "Reload fragment");
}
}
Always make sure that you search for answers throughly before asking your question. For instance, the first place you should check would be: https://developer.android.com/reference/android/support/v4/view/ViewPager.html
You can use viewPager.getCurrrentItem() to get the currently selected index, and from that you should be able to extrapolate which fragment is shown. However what you probably want is to use addOnPageChangeListener() to add an OnPageChangeListener. This will let you keep track of what page is selected, as it's selected by implementing the onPageSelected(int selected) method.
Did you try the isVisible method in the fragment?
Nowadays you can override androidx.fragment.app.onResume and androidx.fragment.app.onPauseto detect if it is visible or not respectively.
I have a ViewPager using a FragmentPagerAdapter for displaying three tabs, each represented by its ow fragment. One of these fragments contains a list, that should be updated on switching / swiping to that tab. But I don't find any way to make it happen. I tried using the onResume method, but the fragments seem not to be paused and resumed on tab change. I also tried using ViewPager.OnPageChangeListener in my MainActivity:
#Override
public void onPageSelected(int position)
{
FragmentRefreshInterface currentFragment = (FragmentRefreshInterface) mSectionsPagerAdapter.getItem(position);
currentFragment.onRefreshed();
}
And in the fragment I use the following:
#Override
public void onRefreshed()
{
List<Record> records = mRecordingService.getRecords();
mRecordAdapter.clear();
mRecordAdapter.add(record);
}
But using this code I can't access my RecordingService class that is used to provide the database functions (because mRecordingService seems to be null). I initialize it in the fragment like this:
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
mRecordingService = new RecordingService(getContext());
}
Using the onPageChangeListener is the correct way to do it. I believe the reason why your code is not working, is because you are calling getItem on your pager adapter: getItem() actually returns a new instance of the fragment. In order to get the current instance, you use instantiateItem() (which returns a reference to the fragment actually being used).
Change your code to look something like this:
#Override
public void onPageSelected(int position)
{
FragmentRefreshInterface currentFragment = (FragmentRefreshInterface) mSectionsPagerAdapter.instantiateItem(viewPager,position);
currentFragment.onRefreshed();
}
And it should work.
I suggest that the code you have in onRefreshed() go in onResume() instead. Fragment doesn't have an onRefreshed() method. You must be implementing another interface that declares this method.
Since you are storing data in a database, you should be use a CursorAdapter or subclass such as SimpleCursorAdapter. If you do this correctly, the ListView will automatically update when you add a record to the database. Then the service can add records without needing to access the service from the fragment.
In your MainActivity:
private FirstFragment firstFragment;
private WantedFragment wantedFragment;
private ThirdFragment thirdfragment;
In getItem
switch(postition){
//return first, wanted, third fragments depending on position
}
onPageSelected:
if(position == 1) // position of the wanted fragment
wantedfragment.onRefreshed()
My ViewPager is located in nested fragment, because i also have navigation drawer. My question is how can i call instance of viewpager in MainActivity.java, so i can set current item of viewpager using method setCurrentItem() from MainActivity.java in method onBackPressed(), when for example user is on third fragment of viewpager and when he presses back button he should be returned on first fragment.
First, you have to declare RecyclerView as public. Not sure if it has to be static, but it'll tell you if it has to.
Second, you need to call an instance of the fragment that holds the RecyclerView.
For example, Fragment recyclerFrag = new RecyclerFrag();
After that, try calling your RecyclerView from that instance and use setCurrentItem(). For example, recyclerFrag.recyclerView.setCurrentItem(0).
I have found a solution. You should first create one method in FragmentActivity where is initialized your ViewPager and set return type ViewPager. Something like this:
public ViewPager getViewPager() {
return mViewPager; // instance of view pager
}
After that create object of your Fragment in Activity where you are calling instance of view pager like this:
YourFragment fragment = new YourFragment();
And in my case i should call viewpager in onBackPressed():
HomeFragment fragment1 = new HomeFragment();
if (fragment1.getViewPager().getCurrentItem() == 1 || fragment1.getViewPager().getCurrentItem() == 2) {
fragment1.getViewPager().setCurrentItem(0);
} else {
super.onBackPressed();
}