/* | |
Extension of FragmentStatePagerAdapter which intelligently caches | |
all active fragments and manages the fragment lifecycles. | |
Usage involves extending from SmartFragmentStatePagerAdapter as you would any other PagerAdapter. | |
*/ | |
public abstract class SmartFragmentStatePagerAdapter extends FragmentStatePagerAdapter { | |
// Sparse array to keep track of registered fragments in memory | |
private SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>(); | |
public SmartFragmentStatePagerAdapter(FragmentManager fragmentManager) { | |
super(fragmentManager); | |
} | |
// Register the fragment when the item is instantiated | |
@Override | |
public Object instantiateItem(ViewGroup container, int position) { | |
Fragment fragment = (Fragment) super.instantiateItem(container, position); | |
registeredFragments.put(position, fragment); | |
return fragment; | |
} | |
// Unregister when the item is inactive | |
@Override | |
public void destroyItem(ViewGroup container, int position, Object object) { | |
registeredFragments.remove(position); | |
super.destroyItem(container, position, object); | |
} | |
// Returns the fragment for the position (if instantiated) | |
public Fragment getRegisteredFragment(int position) { | |
return registeredFragments.get(position); | |
} | |
} |
This comment has been minimized.
This comment has been minimized.
rnascimento13
commented
Jun 24, 2015
thank you very mutch... work like a charm |
This comment has been minimized.
This comment has been minimized.
gustavogianordoli
commented
Oct 20, 2015
Nice!!!!! I would make a little change and use generics so we don't need to cast when getting the fragment: public abstract class SmartFragmentStatePagerAdapter<T extends Fragment> extends FragmentStatePagerAdapter {
private SparseArray<T> registeredFragments = new SparseArray<T>();
public SmartFragmentStatePagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
// Register the fragment when the item is instantiated
@Override
public Object instantiateItem(ViewGroup container, int position) {
T fragment = (T) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
// Unregister when the item is inactive
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
// Returns the fragment for the position (if instantiated)
public T getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
} Now, when you extends this class, specify your fragment type: public class MyPageAdapter extends SmartFragmentStatePagerAdapter<MyFragment> {
.... |
This comment has been minimized.
This comment has been minimized.
kanglongba
commented
Oct 30, 2015
Nice, it help me a lot for understanding a cache for fragment |
This comment has been minimized.
This comment has been minimized.
anshul90
commented
Nov 6, 2015
Can you please give me a small example how I can manage my Fragments (with AsyncTasks) of ViewPager inside a Fragment by using this adapter? |
This comment has been minimized.
This comment has been minimized.
hashbrown
commented
Feb 20, 2016
This will lose its state on configuration change. The FragmentStatePagerAdapter will restore its cached fragment instances, and this object will have no registered instances. |
This comment has been minimized.
This comment has been minimized.
asamoylenko
commented
Apr 7, 2016
@hashbrown yep! |
This comment has been minimized.
This comment has been minimized.
f8full
commented
Apr 18, 2016
It helped so much ! |
This comment has been minimized.
This comment has been minimized.
iRYO400
commented
Jun 25, 2016
Is there anyway to refresh current fragment? |
This comment has been minimized.
This comment has been minimized.
MahdiPishguy
commented
Jul 29, 2016
•
Hi thank you very much, |
This comment has been minimized.
This comment has been minimized.
ghost
commented
Oct 21, 2016
firstly thanks you! hoping it is useful to me, |
This comment has been minimized.
This comment has been minimized.
For those running into orientation change issues on rotation, I wanted to post a quick fix until we have a better workaround. In the // Add to `SmartFragmentStatePagerAdapter.java` as a new method
// Returns the fragment for the position (if instantiated)
public Fragment fetchFragmentByPosition(ViewGroup pagerInstance, int position) {
Fragment existingInstance = registeredFragments.get(position);
if (existingInstance != null) {
return existingInstance;
} else {
return instantiateItem(pagerInstance, position);
}
} In the parent activity or fragment where the adapter instance is available: // In the Activity or wherever you have access to the view pager instance
adapter.fetchFragmentByPosition(mPager, 0); This should allow you to get access to the instance even when the |
This comment has been minimized.
This comment has been minimized.
kaushiknsanji
commented
Dec 4, 2017
•
@nesquena return (Fragment)instantiateItem(pagerInstance, position); To simplify the class, I think we can have only one method instead of two doing the same work of getting the Registered Fragment - // Returns the fragment for the position (if instantiated)
public Fragment getRegisteredFragment(int position) {
Fragment existingInstance = registeredFragments.get(position);
if (existingInstance != null) {
return existingInstance;
} else {
return (Fragment) instantiateItem(pagerInstance, position);
}
} Wish I had this code earlier. I came across such a situation, and did not know what to do. Spent a lot of time, and finally made a hack from reading the internal code of //Sparse Array to keep track of the registered fragments in memory
private SparseArray<Fragment> mRegisteredFragments = new SparseArray<>();
//Stores a reference to the FragmentManager used
private FragmentManager mFragmentManager;
public SmartFragmentStatePagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
mFragmentManager = fragmentManager;
}
/**
* Overriding to restore the state of Registered Fragments array
*
* @param state is the Parcelable state
* @param loader is the ClassLoader required for restoring the state
*/
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
super.restoreState(state, loader);
if (state != null) {
//When the state is present
Bundle bundle = (Bundle) state;
//Setting the ClassLoader passed, onto the Bundle
bundle.setClassLoader(loader);
//Retrieving the keys used in Bundle
Set<String> keyStringSet = bundle.keySet();
//Iterating over the Keys to find the Fragments
for (String keyString : keyStringSet) {
if (keyString.startsWith("f")) {
//Fragment keys starts with 'f' followed by its position index
int position = Integer.parseInt(keyString.substring(1));
//Getting the Fragment from the Bundle using the Key through the FragmentManager
Fragment fragment = mFragmentManager.getFragment(bundle, keyString);
if (fragment != null) {
//If Fragment is valid, then update the Sparse Array of Registered Fragments
mRegisteredFragments.put(position, fragment);
}
}
}
}
} |
This comment has been minimized.
This comment has been minimized.
Coehill
commented
Jan 27, 2018
•
I'm getting
Do you know what might be causing this? EDIT: I had to change:
to:
|
This comment has been minimized.
This comment has been minimized.
q00u
commented
Aug 4, 2018
I'm still having trouble getting this to work after rotation. Is there an example project? |
This comment has been minimized.
benkissi commentedJan 29, 2015
Cool have been looking for this