I have implemented view pager using the FragmentStatePagerAdapter. I have used 3 fragments in the view. The view pager is showing all 3 tabs with views as it should be , now my issue is that the third fragment is not visible but i am able to scroll till third tab and when i scroll back i see the second fragment but again the first fragment vanishes and all i am left is with second fragment.
mPager = (ViewPager)mContext.findViewById(R.id.viewPager);
mPager.setOnPageChangeListener(this);
mPagerAdapter = new MyPagerAdapter(mContext.getSupportFragmentManager(),mContext);
mPager.setAdapter(mPagerAdapter);
adapter code is
public class MyPagerAdapter extends FragmentStatePagerAdapter {
private int NUM_PAGES = 3;
List<Fragment> listFragment = new ArrayList<Fragment>();
private MyActivity mContext;
public MyPagerAdapter(FragmentManager fragmentManager, MyActivity mActivity) {
super(fragmentManager);
this.mContext = mActivity;
listFragment.add(new FirstFragment());
listFragment.add(new SecondFragment());
listFragment.add(new ThirdFragment());
}
#Override
public int getItemPosition(Object object){
return PagerAdapter.POSITION_NONE;
}
#Override
public Fragment getItem(int position) {
Log.v("fragment position",""+position);
return listFragment.get(position);
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
I am stuck in this for a while, i would really appreciate some help.Thank you.
It is advised to use FragmentPagerAdapter instead of FragmentStatePagerAdapter, because of very nature of those two. FragmentStatePagerAdapter is being that is able to scroll through infinite views. In case of fixed amount of them, like your case you should use FragmentPagerAdapter.
If you happen to have context issues later override following method:
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
mFragments.remove(position);
mFragments.add(position, fragment);
return fragment;
}
Where mFragments is your list.
Related
So i have the next problem with FragmentPagerAdapter. I have a TabLayout with 3 tabs representing 3 fragments that i can switch. So when i switch to third fragment, for some reason the first one disappears (or its view). Does anyone know how to fix this problem? Thanks in advance.
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private static final int FRAGMENT_COUNT = 3;
private final List<Fragment> listOfFragments = new ArrayList<>();
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return listOfFragments.get(position);
}
#Override
public int getCount() {
return FRAGMENT_COUNT;
}
public void addFragment(Fragment fragment) {
listOfFragments.add(fragment);
}
}
This is the code for FragmentPagerAdapter.
And i think i fixed this :) Only thing i did is to override the FragmentPagerAdapter destroyItem() method, with empty body (no super).
I don't know what is your problem. but if in your app only 3 fragments are there than you can try setOffscreenPageLimit method of ViewPager
ViewPager.setOffscreenPageLimit(3);
One of the problems here is a slightly confusing API.
In FragmentPagerAdapter, getItem(int position) actually means "create item". In other words, you shouldn't try to manually cache the Fragments inside a list in your Adapter.
#Override
public Fragment getItem(int position) {
return listOfFragments.get(position); //No! don't do this
}
Even though it may see counter-intuitive, you should actually create a new instance of the Fragment you want inside getItem, sticking very closely to the official Google example:
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return FirstFragment.getInstance();
case 1:
return SecondFragment.getInstance();
}
}
Otherwise you will run into problems where the FragmentManager's cache and your own List<Fragment> cache are out-of-sync. In short, caching of Fragments is handled by the FragmentManager and you don't need to roll-your-own caching.
I don't know really what happen but this is my code, hope this help you
public class AdapterFragmentViewPager extends FragmentPagerAdapter {
private List<Fragment> fragmentList = new ArrayList<>();
public AdapterFragmentViewPager(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment) {
fragmentList.add(fragment);
}
#Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
#Override
public int getCount() {
return fragmentList.size();
}
}
and this is my Tablayout:
private AdapterFragmentViewPager adapterFragmentViewPager = new AdapterFragmentViewPager(getSupportFragmentManager());
TabLayout.Tab home = tabLayout.newTab();
tabLayout.addTab(home);
TabLayout.Tab newest = tabLayout.newTab();
tabLayout.addTab(newest);
TabLayout.Tab author = tabLayout.newTab();
tabLayout.addTab(author);
TabLayout.Tab category = tabLayout.newTab();
tabLayout.addTab(category);
TabLayout.Tab saved = tabLayout.newTab();
tabLayout.addTab(saved);
adapterFragmentViewPager.addFragment(FragmentHome.newInstance());
adapterFragmentViewPager.addFragment(FragmentQuote.newInstance());
adapterFragmentViewPager.addFragment(FragmentAuthor.newInstance());
adapterFragmentViewPager.addFragment(FragmentCategory.newInstance());
adapterFragmentViewPager.addFragment(FragmentFavorites.newInstance());
viewPager.setAdapter(adapterFragmentViewPager);
tabLayout.setupWithViewPager(viewPager);
Fragment with RecyclerView is having problem inside ViewPager. Duplicate RecyclerView appears overlapped when the fragments gets recreated after swiping.
I am using ViewPager, Fragment, FragmentStatePagerAdapter
Pic 1 : For the first time there RecyclerView is fine.
Pic 2 : After swiping multiple fragments and then swiping back to same fragment then duplicate fragments gets overlapped while scrolling.
using FragmentStatePagerAdapter
class SlidingFragmentPagerAdapter extends FragmentStatePagerAdapter {
SparseArray<FragmentMain> registeredFragments = new SparseArray<FragmentMain>();
FragmentManager fm;
public SlidingFragmentPagerAdapter(FragmentManager fm) {
super(fm);
this.fm = fm;
}
#Override
public Fragment getItem(int position) {
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1 * (FragmentViewPager.MAX_PAGE - position - 1));
return FragmentMain.newInstance(position + "", cal.getTime());
}
#Override
public int getCount() {
return MAX_PAGE;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
FragmentMain fragment = (FragmentMain) 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 FragmentMain getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
}
Using ViewPager
mViewPager = (ViewPager) view.findViewById(R.id.viewpager);
rootView.findViewById(R.id.img_floating_btn2);
mSlidingTabLayout = (SlidingTabLayout) view.findViewById(R.id.sliding_tabs);
mSlidingTabLayout.setDistributeEvenly(true);
adapter = new SlidingFragmentPagerAdapter(getFragmentManager());
mViewPager.setAdapter(adapter);
mViewPager.setCurrentItem(MAX_PAGE);
mSlidingTabLayout.setViewPager(mViewPager);
Note
I tried using mViewPager.setOffscreenPageLimit(adapter.getCount()); buti have more than 50 fragments in ViewPager
I had the same problem, I had a ViewPager with a RootFragment containing other fragments. I added these fragments to the RootFragment with:
getFragmentManager().beginTransaction().add(containerLayout.getId(), ItemFragment.newInstance()).commit();
I fixed it by changing it to replace instead of add.
getFragmentManager().beginTransaction().replace(containerLayout.getId(), ItemFragment.newInstance()).commit();
Even when the container is empty you have to use replace instead of add!
I am using FragmentPagerAdapter and a ViewPager to add custom Fragments EDIT: from my MainActivity (also sending a bunch of extra data based on a JSON response via bundle) and using swiping motions to move to the next Fragments in the List.
public class MyPagerAdapter extends FragmentPagerAdapter implements Serializable {
public List<Fragment> fragments;
public FragmentManager fm;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
this.fm = fm;
this.fragments = new ArrayList<Fragment>();
}
#Override
public Fragment getItem(int position) {
return fragments.get(position);
}
#Override
public int getCount() {
return fragments.size();
}
}
Everything is working fine as long as I'm adding new Fragments by
using
MyPagerAdapter pageAdapter = new MyPagerAdapter(getSupportFragmentManager());
pager = (ViewPager)findViewById(R.id.myViewPager);
pageAdapter.fragments.add(new CustomFragment());
pager.setAdapter(pageAdapter);
But I can't find a proper way to add Fragments to the beginning of the List and swipe back.
I've tried both
pageAdapter.fragments.add(0, new CustomFragment());
as well as changing the FragmentPagerAdapters List to LinkedList and using
pageAdapter.fragments.addFirst(new CustomFragment());
and then refreshing the adapter by using
pageAdapter.notifyDataSetChanged();
and i keep getting the following exception:
java.lang.IllegalStateException: Can't change tag of fragment CustomFragment{2ead9520 #10 id=0x7f0a0002 android:switcher:2131361794:10}: was android:switcher:2131361794:10 now android:switcher:2131361794:11
The key methods no one has talked about yet is public int getItemPosition(Object) which is used to remap fragments to pages after they move and public long getItemId(int position) which must be overridden by a pager adapter that reorders fragments. The default implementation uses the position of the page as the id, so reordering confuses the FragmentPagerAdapter.
(I am leaving out the Serializable interface as it is irrelevant for the purposes of answering the question - How to reorder fragments in a FragmentPagerAdapter).
public class MyPagerAdapter extends FragmentPagerAdapter {
public List<Fragment> fragments;
public FragmentManager fm;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
this.fm = fm;
this.fragments = new ArrayList<Fragment>();
}
void addFragmentAtPosition(int position, Fragment f) {
if(position == fragments.size())
fragments.add(f);
else
fragments.add(position, f);
notifyDataSetChanged();
}
void removeFragmentAtPosition(int position) {
Fragment f = fragments.remove(position);
if(f != null)
fm.beginTransaction().remove(f).commit();
notifyDataSetChanged();
}
#Override
public Fragment getItem(int position) {
return fragments.get(position);
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public int getItemPosition(Object object){
/*
* called when the fragments are reordered to get the
* changes.
*/
int idx = fragments.indexOf(object);
return idx < 0 ? POSITION_NONE : idx;
}
#Override
public long getItemId(int position) {
/*
* map to a position independent ID, because this
* adapter reorders fragments
*/
return System.identityHashCode(fragments.get(position));
}
}
The key additions are the overrides of public int getItemPosition(Object) and public long getItemId(int). These allow the FragmentPagerAdapter to reposition the existing fragments and to identify the existing active fragments in the FragmentManager cache correctly.
You should not create and add fragments this way. Instead just instantiate the fragments in getItem and the adapter will take care of using them. just do this:
#Override
public Fragment getItem(int position) {
Fragment fragment = new CustomFragment();
fragments.add(fragment)
return fragment
}
I would suggest you don't keep a list of references to fragments since it is not necessary and you risk to create memory leaks.
What i would do is create the fragment only when required like this :
#Override
public Fragment getItem(int position) {
Fragment fragment = new MyFragment();
return fragment;
}
To solve your problem you should create the fragment based on your needs, for example if you have fragments of different class instances like for example one instance of MyFragment another one of YourFragment and so on, just keep a list which says which kind of fragment occupy that position.
For example:
myListMap = new HashMap<Integer, Integer>();
myListMap.put(position, type);
and then create the fragment on the fly:
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
int type = ...find fragment type in that position ....
if(type == MYFRAGMENTTYPE) {
fragment = new MyFragment();
}
return fragment;
}
Don't know if you still need the answer, but I was trying to do something similar and just found the solution :)
You are receiving that exception because of your getItem function. You are returning the fragment in the position that the function receives, and this position is always the last position of the array because that would correspond to the last added fragment in a "typical" usage.
In your case, you want to add a new Fragment in the first position, so your getItem will return twice the same fragment and throw the exception.
To avoid this you need to create a public function into your Adapter and the index of the fragment you are adding, and then return this specific fragment.
PS.: I'm developing only in Kotlin for about 6 months now, so it can have some typos.
public int newFragmentIndex = 0;
public List<Fragment> fragments;
...
public void addFragmentAt(int index, Fragment fragment) {
newFragmentIndex = index;
pageAdapter.fragments.add(index, fragment);
notifyDataSetChanged();
}
public void addFragment(Fragment fragment) {
newFragmentIndex = fragments.size();
pageAdapter.fragments.add(fragment);
notifyDataSetChanged();
}
...
#Override
public Fragment getItem(int position) {
return fragments.get(newFragmentIndex);
}
To call this from your Activity, change your pageAdapter.fragments.add(new CustomFragment());
to
pageAdapter.fragments.addFragment(new CustomFragment());
And
pageAdapter.fragments.add(0, new CustomFragment());
to
pageAdapter.fragments.addFragmentAt(0, new CustomFragment());
Hope this helps you with your problem!
Here , I explain my problem. I install a ViewPager and FragmentPagerAdapter so you can slide between two page.
Each fragment contains data ( TextView ) .
When creating my ViewPager with the data passed as a parameter everything goes well.
But if I want to change the data (ie the content of the fragment) it does not refresh
public class MaPagerAdapter extends FragmentPagerAdapter {
private Meteo[]lameteo;
public MaPagerAdapter(FragmentManager fm, Meteo[]lameteo) {
super(fm);
this.lameteo = lameteo;
Log.i("aa", "ville maPagerAdapter"+lameteo[0].getLoc());
}
#Override
public Fragment getItem(int position) {
switch(position) {
case 0: return page_droite.newInstance(lameteo[0]);
case 1: return page_gauche.newInstance(lameteo);
}
return null;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
public void setData(Meteo[] meteo){
this.lameteo=meteo;
}
#Override
public int getCount() {
return 2;
}
}
And my main
if(mPagerAdapter!=null){ //if pagerAdapter already initialized
mPagerAdapter.setData(meteo);
mPagerAdapter.notifyDataSetChanged();
}else
mPagerAdapter = new MaPagerAdapter(getSupportFragmentManager(), meteo);
ViewPager pager = (ViewPager) findViewById(R.id.viewpager);
pager.setAdapter(mPagerAdapter);
Can you help me please ?
No, the pager adapter doesn't work that way. Android doesn't realize that you have that particular data in your fragments, so it wouldn't know how to update it.
You'll have to get references to your fragments inside your setData call, and then you'll have to write new methods inside your fragments that you can call to reset their data. Inside the fragments, you'll have to make sure that you update the fragment's views with the new data. But as for you adapter, you can do something like this:
public class MaPagerAdapter extends FragmentPagerAdapter {
private Meteo[]lameteo;
private FragmentManager fm;
public MaPagerAdapter(FragmentManager fm, Meteo[]lameteo) {
super(fm);
this.fm = fm;
this.lameteo = lameteo;
Log.i("aa", "ville maPagerAdapter"+lameteo[0].getLoc());
}
public void setData(Meteo[] meteo){
this.lameteo=meteo;
page_droite droite = (page_droite) getFragment(0);
droite.setData(meteo[0]);
page_gauche gauche = (page_gauche) getFragment(1);
gauche.setData(meteo);
}
private Fragment getFragment(int position) {
String tag = "android:switcher:" + R.id.viewpager + ":" + getItemId(position);
return fm.findFragmentByTag(tag);
}
Note that there is no need to call notifyDataSetChanged in this case, since you still have the same fragment in your adapter. When you implement the setData functions in your fragments, you need to make all the changes then.
I've got a FragmentActivity when I instantiate three different (n, n+1, n+2) Fragments.
I need to keep each Fragment updated when user swipes to it, so I used ViewPager.SimpleOnPageChangeListener.onPageSelected in the Fragment Activity, so when user swipes to n+1 or n+2 Fragment and again to n that function update the content.
Without using this workaround if I'm in the Fragment n+1, both n and n+2 are already loaded! I'd like instead that the Fragment load when the user swipes to it, without "pre-load".
This workaround works fine for me but it has a problem: the n Fragment that is the first in the list at start up of the app doesn't load its content. To load its content I have to swipe to n+1 then go back to n.
I know that the content of the Fragment should be setted on the class called at the moment of instantiate the fragment and that extends Fragment class, but in this way I don't know how to keep up to date each Fragment, as I do using onPageSelected.
Any suggestions?
EDIT 1:
I istantiate my fragments in this way in onCreate():
for(int x = 0; x < 3; x++) {
Bundle b = new Bundle();
b.putString( "id" , x );
Fragment myFrag = Fragment.instantiate( myContext , Mm_FragmentPage.class.getName() );
myFrag.setArguments( b );
fragments.add(myFrag);
}
Then I set the adapter in the ViewPager:
mPagerAdapter = new PagerAdapter( super.getSupportFragmentManager() , fragments );
mPager.setAdapter( mPagerAdapter );
Then I use the adapter in the TitlePageIndicator
titleIndicator = (TitlePageIndicator) findViewById( R.id.titleFragments );
titleIndicator.setViewPager( mPager );
titleIndicator.setOnPageChangeListener( new myPageChangeListener() );
And, at the end, the class PagerAdapter:
public class PagerAdapter extends FragmentPagerAdapter
{
// fragments to instantiate in the viewpager
private List<Fragment> fragments;
// constructor
public PagerAdapter(FragmentManager fm, List<Fragment> fragments)
{
super(fm);
this.fragments = fragments;
}
// return access to fragment from position, required override
#Override
public Fragment getItem(int position)
{
return this.fragments.get(position);
}
// number of fragments in list, required override
#Override
public int getCount()
{
return this.fragments.size();
}
#Override
public CharSequence getPageTitle(int position)
{
return getResources().getStringArray( R.array.tab_header_name )[ position ];
}
}
OK, so first thing you need to set OnPageChangeListener on the ViewPager and implement method onPageSelected(int i) and call the adapter's notifyDataSetChanged(), like so:
mPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int i, float v, int i2) {
}
#Override
public void onPageSelected(int i) {
//Tell the adapter that the content was changed
mPager.getAdapter().notifyDataSetChanged();
}
#Override
public void onPageScrollStateChanged(int i) {
}
});
In order to keep the fragments updated, you need to extends FragmentStatePagerAdapter and not FragmentPagerAdapter like what you did. The difference is that with FragmentPagerAdapter the ViewPager will never re-create the fragments, while in FragmentStatePagerAdapter it will.
Then on getItem(..) make sure to return a new instance of the fragment with the new content by passing the content to its arguments via setArguments(). Then override also getItemPosition(..) to tell the adapter that the fragment is not found, and therefore it must re-create it.
public class MyPagerAdapter extends FragmentStatePagerAdapter {
//List to hold the fragments to be shown
//NOTE: It's a list of Fragment classes, not a list of Fragment instances!
private List<Class<? extends Fragment> fragments;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
fragments.add(SomeFragment.class);
fragments.add(AnotherFragment.class);
fragments.add(MoreFragment.class);
}
#Override
public Fragment getItem(int i) {
try {
//Creates a new instance of the fragment
Fragment instance = fragments.get(i).newInstance();
//Put the new content by passing Bundle with new content
instance.setArguments(args);
return instance;
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return null;
}
#Override
public int getItemPosition(Object object) {
//NOTE: you might want to put better logic here
return POSITION_NONE;
}
#Override
public int getCount() {
return pages.size();
}
}
Every time you slide from one fragment to another, onPageSelected() will be fired calling notifyDataSetChanged() which will force the adapter to check also if the position of the fragment has changed. Since we return POSITION_NONE in getItemPosition(..), the adapter thinks that the position changed and will then call getItem(i). In getItem(i) we return a new instance (optionally, passing new arguments). Problem solved! :)
I just tested it by myself, created a small app that have a counter which increases everytime the user slides the page and it works!
This way you can drop the ViewPager.SimpleOnPageChangeListener.onPageSelected.
Learn more about ViewPager.