I have viewpager with some fragments and i set to each fragment my model class according which UI of fragment should be edited. That model class i set to fragment at constructor before i add that fragment to FragmentStatePagerAdapter. My problem is that after rotating screen or when system kills my application and i restore it, my fragment are recreated by system and my model class instance is lost. Even if I set new FragmentStatePagerAdapter, fragments created by system are visible. Is there any right way of achive that i create new instances of my fragments and place them into viewpager? I tried so many thinks like removing fragments from FragmentManager, adding Adapter to viewpager again, change FragmentStatePagerAdapter only to FragmentPagerAdapter and nothing helped.
My activity class with loading model classes in loader from some resource:
List<Fragment> visibleFragment = new ArrayList<Fragment>();
for (Screen screen : wizard.screens) {
if (screen.visible) {
visibleFragment.add(new ScreenUI(screen));
}
}
viewPager.setAdapter(null);
viewPager.setAdapter(new WizardPagerAdapter(getSupportFragmentManager(), visibleFragment));
My FragmentStatePagerAdapter
public class WizardPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments;
private final int count;
public WizardPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
mFragments = fragments;
count = mFragments.size();
}
#Override
public Fragment getItem(int index) {
return mFragments.get(index);
}
#Override
public int getCount() {
return count;
}
}
try add in Manifest android:configChanges="orientation|keyboardHidden|screenSize" to activity.
OR something like that
public class ViewPagerTaskAdapter extends FragmentStatePagerAdapter {
Map<Integer, FragmentViewTask> fragmentsTask = new HashMap<Integer, FragmentViewTask>();
#Override
public Fragment getItem(int arg0) {
FragmentViewTask myFragment = FragmentViewTask.newInstance(arg0,
tasks.get(arg0));
fragmentsTask.put(arg0, myFragment);
return myFragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
fragmentsTask.remove(position);
}
public FragmentViewTask getFragment(int key) {
return fragmentsTask.get(key);
}
#Override
public int getCount() {
if (tasks != null)
return tasks.size();
return 0;
}
}
Have you tried using onRetainInstance(true) on your Fragments?
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
Related
I'm using a Fragment on my Activity that will have a picture "swiper". I've created a FragmentStatePagerAdapter which I'm trying to call from this Fragment and for some reason my getItem() method is never being called.
I've searched and found that I need to use getChildFragmentManager() when instantiating my FragmentStatePagerAdapter because I'm calling it from a Fragment. I've tried this as well as getSupportFragmentManager() with no luck from either.
Any ideas?
here's my Fragment that I'm using on my MainActivity with the method that shoudl setup the FragmentStatePagerAdapter:
public class PhotoFlipper extends Fragment {
// properties and fields
// primitive types
String currentImage;
int friendShareType = 0;
ImageView share;
ViewPager pager;
PhotoFlipperItemAdapter pagerAdapter;
LatLng itemPosition;
Activity activity;
FragmentActivity fragActivity;
public ArrayList<MarkerModel> picsAndVids;
// end properties and fields
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View photoFlipperFragmentView = inflater.inflate(R.layout.photo_flipper_layout, container, false);
InitializeFragment(photoFlipperFragmentView);
return photoFlipperFragmentView;
}
private void InitializeFragment(View photoFlipperFragmentView) {
activity = getActivity();
fragActivity = (FragmentActivity)activity;
pager = (ViewPager)photoFlipperFragmentView.findViewById(R.id.photoflipper_pager);
share = (ImageView)photoFlipperFragmentView.findViewById(R.id.photoflipper_share);
share.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
IPictureFlipper iPictureFlipper = (IPictureFlipper)activity;
iPictureFlipper.ShareVideoOrImage(friendShareType, itemPosition, currentImage);
}
});
}
#Override
public void onHiddenChanged(boolean hidden) {
super.onHiddenChanged(hidden);
if (hidden) {
pager.setVisibility(View.GONE);
}
}
public void SetTappedPicture(int index) {
pagerAdapter = new PhotoFlipperItemAdapter(getChildFragmentManager(), picsAndVids, picsAndVids.size());
pager.setAdapter(pagerAdapter);
pager.setCurrentItem(index);
pager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
}
});
}
}
And here's my FragmentStatePagerAdapter:
public class PhotoFlipperItemAdapter extends FragmentStatePagerAdapter {
ArrayList<MarkerModel> _markers;
int NUM_PAGES;
String TAG = "home";
public PhotoFlipperItemAdapter(FragmentManager fm, ArrayList<MarkerModel> markers, int numpages){
super(fm);
Log.d(TAG,"in adapter in constructor");
_markers = markers;
NUM_PAGES = numpages;
}
#Override
public Fragment getItem(int position) {
Log.d(TAG,"in adapter in get item");
Fragment fragment = PhotoFlipperItemFragment.create(position, _markers);
return fragment;
}
#Override
public int getCount() {
Log.d(TAG,"in adapter in get count: "+NUM_PAGES);
return NUM_PAGES;
}
}
logcat is showing me that NUM_PAGES is > 0 so that's not my issue. I see my log in the constructor and in getCount() but nothing in getItem().
TIA
I got this sorted out. I was hiding my fragment in my InitializeActivity() right after I added it to my FragmentManager so it was never fully building the Fragment with the ViewPager etc.
I'm going to have to come up with a different solution for hiding/showing the fragment but that was my problem.
I have a problem while changing fragments in my viewpager. In specific, my fragment is replaced with an empty one.
Here's some code:
public void replaceFragment() {
supportManager.getFragments().set(1,getNewFragment()));
pageAdapter.notifyDataSetChanged();
menuControl.setView(1);//this just changes the fragment to be shown
}//here is where i change the fragment
//and here is the adapter
public class SimplePageAdapter extends FragmentPagerAdapter{
final List<Fragment> fragment;
final FragmentManager fragmentManager;
public SimplePageAdapter(FragmentManager fm, List<Fragment> fragment) {
super(fm);
fragmentManager = fm;
this.fragment=fragment;
}
#Override
public Fragment getItem(int arg0) {
return fragment.get(arg0);
}
#Override
public int getCount() {
return fragment.size();
}
#Override
public int getItemPosition(Object o) {
return POSITION_NONE;//I read that this is for making notifyDataSet work
}
}
I want to prepend a new View as first page of my ViewPager.
My adapter looks like this:
public class PagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> fragments;
public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
#Override
public Fragment getItem(int index) {
return fragments.get(index);
}
#Override
public int getCount() {
return fragments.size();
}
public void add(int i, ImageFileObject imageFile) {
ImageViewFragment f = new ImageViewFragment();
f.setImage(imageFile);
fragments.add(0, f);
notifyDataSetChanged();
}
public void add(ImageFileObject imageFile) {
ImageViewFragment f = new ImageViewFragment();
f.setImage(imageFile);
fragments.add(f);
notifyDataSetChanged();
}
}
But when calling add(0, aImageFile) the item is not prepended to the fragment list. (It's not even appended).
Any ideas?
Update: The problem that you described in comment is real, I missed it in first testing. After analyzing the source code of FragmentPagerAdapter I realized that all we need to do is to Override getItemId() in a way that it won't return same id for different fragment items. E.g. current default implementation would just return position as an id for fragment which won't work for this case:
public long getItemId(int position) {
return position;
}
I am updating this answer, please have a look. As before I have tested this code and the problem you described is not happening now.
Only thing you need is not to keep reference of fragments by yourself in List, This is done for you by FragmentPagerAdapter. And as far as I know its not a good practise either. And also even if you return POSITION_NONE from getItemPosition() as suggested by other answer(s), you will end up with Exception
Caused by: java.lang.IllegalStateException: Can't change tag of fragment.
This is because you are trying to reposition alive Fragments in your List by adding a fragment at 0th index (which causes other fragments to reposition) and ViewPager assigns tags based on position.
Keeping all this in mind, here is a tested and working modified adapter:
public class PagerAdapter extends FragmentPagerAdapter {
public static class FragmentInfo {
public String classz;
public ImageFileObject imageFile;
public static long IDS;
public long id;
public FragmentInfo(){
id = IDS++;
}
}
private final List<FragmentInfo> fragments;
private Context context;
public PagerAdapter(FragmentManager fm, List<FragmentInfo> fragments,
Context context) {
super(fm);
this.fragments = fragments;
this.context = context;
}
#Override
public Fragment getItem(int index) {
FragmentInfo info = fragments.get(index);
ImageViewFragment frag = (ImageViewFragment) Fragment.instantiate(
context, info.classz, /* null arguments*/ null);
frag.setImage(info.imageFile);
return frag;
}
#Override
public long getItemId(int position) {
return fragments.get(position).id;
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
public void add() {
FragmentInfo f = new FragmentInfo();
f.classz = ImageViewFragment.class.getName();
fragments.add(0, f);
notifyDataSetChanged();
}
}
Please change your code accordingly.
The problem is actually with notifyDataSetChanged. Just add to your Adapter:
public int getItemPosition(Object object) {
return POSITION_NONE;
}
However, I think you will get other problems when the Adapter actually tries to call getItem again. These problems will be in the lines of "Fragment Already Added".
I'm working with a FragmentStatePagerAdapter using this example.
The MyAdapter class is implemented as follows:
public static class MyAdapter extends FragmentStatePagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return NUM_ITEMS;
}
#Override
public Fragment getItem(int position) {
return ArrayListFragment.newInstance(position);
}
}
The ListFragment class includes the following method to create a new instance:
/**
* Create a new instance of CountingFragment, providing "num"
* as an argument.
*/
static ArrayListFragment newInstance(int num) {
ArrayListFragment f = new ArrayListFragment();
// Supply num input as an argument.
Bundle args = new Bundle();
args.putInt("num", num);
f.setArguments(args);
return f;
}
When I create a new fragment state pager adapter in my activity, getItem is called, which in turn calls the newInstance method in the ListFragment class. This is great when I want to create a new fragment.
But it's not clear to me how to modify getItem (if even needed) to get the fragment object when it already exists and the user pages from, for example, page 2 to page 1. I'd like my Activity to retrieve that existing, previously created fragment so that it can run an inner class AsyncMethod, which resides in the fragment class.
I think the solution is much simpler than the answers provided.
If you take a look at the source of FragmentStatePagerAdapter.instantiateItem(), you'll notice that instantiateItem() handles this logic for you, and thus your implementation of getItem() should always return a new instance.
So in order to return an existing Fragment, simply do (assuming you're calling from ViewPager):
Fragment f = (Fragment) getAdapter().instantiateItem(this, getCurrentItem());
While #imiric's solution is very concise, it still bothers me that it requires knowledge of the implementation of the class. My solution involves adding the following to your adapter, which should behave nicely with a FragmentStatePagerAdapter possibly destroying fragments:
private SparseArray<WeakReference<Fragment>> mFragments = new SparseArray<>();
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment f = (Fragment) super.instantiateItem(container, position);
mFragments.put(position, new WeakReference<>(f)); // Remember what fragment was in position
return f;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
mFragments.remove(position);
}
public Fragment getFragment(int position) {
WeakReference<Fragment> ref = mFragments.get(position);
Fragment f = ref != null ? ref.get() : null;
if (f == null) {
Log.d(TAG, "fragment for " + position + " is null!");
}
return f;
}
I have implemented something similar to what you have. I extended the FragmentPagerAdapter class like so:
public class ContactsFragmentPagerAdapter extends FragmentPagerAdapter {
ActionBar mActionBar;
private List<Fragment> mFragments;
public ContactsFragmentPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
mFragments = fragments;
}
#Override
public int getCount() {
return mFragments.size();
}
#Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
public void setActionBar(ActionBar bar) {
mActionBar = bar;
}
}
Notice I have added an argument to the constructor to pass in the List of Fragment objects. This way the getItem() method of this class can return any class that extends Fragment or any of its subclasses and not just one specific class ArrayListFragment like you have done.
In the Activity where I instantiate my subclass of FragmentPagerAdapter I have passed in the list of Fragment objects:
Class the instantiates the FragmentPagerAdapter
public final class ContactManager extends Activity {
private ContactsFragmentPagerAdapter mAdapter;
private ViewPager mPager;
public ActionBar mActionBar;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.contact_manager);
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, ContactsListFragment.class.getName()));
fragments.add(Fragment.instantiate(this, GroupsListFragment.class.getName()));
mAdapter = new ContactsFragmentPagerAdapter(this.getFragmentManager(), fragments);
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
mPager.setOnPageChangeListener(new OnPageChangeListener() {
#Override
public void onPageScrollStateChanged(int arg0) {}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {}
#Override
public void onPageSelected(int arg0) {
mActionBar.getTabAt(arg0).select();
}
});
}
}
By accessing the variable "fragments", you can access a previously created Fragment so that you can run methods of that Fragment.
public class MyPagerAdapter extends FragmentStatePagerAdapter {
final Context m_context;
final WeakReference<Fragment>[] m_fragments;
public DetailPagerAdapter(FragmentManager fm) {
super(fm);
m_context = ...
m_fragments = new WeakReference[enter size here];
}
#Override
public Fragment getItem(int position) {
final Fragment fragment = instantiate your fragment;
m_fragments[position] = new WeakReference<Fragment>(fragment);
return fragment;
}
#Override
public int getCount() {
return ...
}
public Fragment getFragment(final int position) {
return m_fragments[position] == null ? null :
m_fragments[position].get();
}
}
Do not need modify the FragmentPagerAdapter, because fragments are cached by the FragmentManager. So you must need find inside it. Use this function to find the fragment by pager adapter position.
public Fragment findFragmentByPosition(int position) {
FragmentPagerAdapter fragmentPagerAdapter = getFragmentPagerAdapter();
return getSupportFragmentManager().findFragmentByTag(
"android:switcher:" + getViewPager().getId() + ":"
+ fragmentPagerAdapter.getItemId(position));
}
Sample code for v4 support api.
I think this could help:
class HomePagerAdapter(fragmentManager: FragmentManager) : FragmentStatePagerAdapter(fragmentManager, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
private val fragmentConstructors: List<() -> Fragment> by lazy {
listOf(
::AuctionLotsFragment,
::ChatListFragment,
::MarketHomeFragment,
::WalletSectionsFragment,
::SettingsFragment
)
}
private val fragments: HashMap<Int, WeakReference<Fragment>> by lazy {
HashMap()
}
override fun getCount(): Int = fragmentConstructors.size
override fun getItem(position: Int): Fragment {
return fragments[position]?.get() ?: this.createFragmentForPosition(position)
}
private fun createFragmentForPosition(position: Int): Fragment {
val fragment = fragmentConstructors[position].invoke()
fragments[position] = WeakReference(fragment)
return fragment
}
}
I have a FragmentList with some items. If I click an item the appropriate Fragment will open which contains a Viewpager. No problem so far but if I go back to the List and click the item again the method getItem(int position) is not called anymore.
Here a link with a similar problem:
Display fragment viewpager within a fragment
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.activity_fragment_runtime, container, false);
mViewPager = (ViewPager) view.findViewById(R.id.pager);
indicator = (TitlePageIndicator) view.findViewById(R.id.indicator);
MyFragmentPagerAdapter mMyFragmentPagerAdapter = new MyFragmentPagerAdapter(getActivity().getSupportFragmentManager());
mViewPager.setAdapter(mMyFragmentPagerAdapter);
indicator.setViewPager(mViewPager);
return view;
}
class MyFragmentPagerAdapter extends FragmentStatePagerAdapter implements TitleProvider {
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public String getTitle(int position) {
return muxbusTitles[position];
}
#Override
public Fragment getItem(int location) {
return muxbusFragmentList.get(location);
}
#Override
public int getCount() {
return muxbusTitles.length;
}
}
return view;
}
Edit:
If someone is interested,the solution was to extends from PagerAdapter instead of FragmentStatePagerAdpater because the Viewpager is already in a Fragment..
I did have similar problem and after scratching my head for quite some time i made an my own understanding (assumption) that ViewPager is keeping the reference of its child fragments into memory even the hosted Fragment or Activity is destroyed (didn't tested with Activity). So i wrote this method freeFragmentsFromViewPager(). You need to call it from onDestroy() of your Fragment.
/**
* This method free the child fragments from ViewPager as ViewPager keeps the reference
* of child fragments into memory and next time when you again come to visit view pager it won't show the fragment layout
* because it has the reference to the fragment whilst the fragment's view was already destroyed.
*/
private void freeFragmentsFromViewPager()
{
for(int i = 0; i < TabsFragmentPagerAdapter.fragments.length; i++)
{
Fragment fragment = TabsFragmentPagerAdapter.fragments[i];
if(fragment != null)
{
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.remove(fragment);
fragmentTransaction.commit();
TabsFragmentPagerAdapter.fragments[i] = null;
}
}
}
And this is my Adapter code
public class TabsFragmentPagerAdapter extends FragmentPagerAdapter
{
public static final int NUM_TABS = 3;
public static Fragment[] fragments = new Fragment[NUM_TABS];
public TabsFragmentPagerAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public Fragment getItem(int position)
{
Log.e("TabsFragmentPagerAdapter", "getItem");
Fragment fragment = TabsFragmentFactory.newInstace(position);
fragments[position] = fragment;
return fragment;
}
#Override
public int getCount()
{
return NUM_TABS;
}
#Override
public CharSequence getPageTitle(int position)
{
return TabsFragmentFactory.getName(position);
}