Develop Reference

Android RecyclerView : Memory usage increases during scrolling if 'setIsRecyclabe(false)' is not used

In my android application(Java) I am displaying a list of around 1800 contacts in a recyclerview. While doing a memory profile it was found that when scrolling the recycler view the memory usage was increasing rapidly. So I found this question here which was mentioning the same problem and tried out the solution which was to setIsRecyclable(false) in onBindViewHolder and it worked. The profiling results are given below.
Case 1 : setIsRecyclable(False) not used
Initial memory usage : ~ 40M
[ Java=5.9M Native=5M Graphics=20.3M Stack=0.3M Code=5.3M Others =0.8M ]
Peak memory usage : ~ 345M
[ Java=187.5M Native=39.1M Graphics=101.5M Stack=0.4M Code=11.6M Others =6.5M ]
Also the peak memory usage was found to increase with increase in number of items in the list. After the continuous scrolling is stopped for a while the memory usage does come down but only to around 162 MB.
Case 2 : after adding setIsRecyclable(False) to onBindViewHolder
Initial memory usage : ~ 42M
[ Java=5.8M Native=5.5M Graphics=20.2M Stack=0.3M Code=9.4M Others =0.8M ]
Peak memory usage : ~ 100M
[ Java=43.9M Native=9.7M Graphics=32.6M Stack=0.4M Code=11.7M Others =2.2M ]
Also, in this case, memory usage was not affected significantly by increasing number of items in list. Although peak memory usage is about 100MB the average stays at around 70 MB for most of the time which is even better.
Source Code of fragment containing recyclerView
Note :
* Adapter class is defined as an inner class of Fragment class and ViewHolder class is defined as an inner class of Adapter class.
* 'App.personList' is a static arrayList holding the list of contacts and App is the ViewModel class.
* adapter1 is the only adapter of interest. Please avoid adapter2(handles another small list)
public class FragmentAllContacts extends Fragment
{
public static MainActivity main;
public RecyclerView contactsView, tagsView;
LinearLayoutManager llm, lln;
Button filterCloseButton;
CardView filterView;
Adapter_ContactListView adapter1;
Adapter_TagListView adapter2;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState)
{
setHasOptionsMenu(true);
main = (MainActivity) getActivity();
return inflater.inflate(R.layout.fragment_all_contacts, container, false);
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
adapter1 = new Adapter_ContactListView(App.personList,getContext());
adapter2 = new Adapter_TagListView(App.tagList,getContext());
filterView = getView().findViewById(R.id.cardView7);
FloatingActionButton fab = getView().findViewById(R.id.create_contact_fab);
contactsView = getView().findViewById(R.id.allContacts_recyclerView);
contactsView.setAdapter(adapter1);
llm = new LinearLayoutManager(main.getBaseContext());
contactsView.setLayoutManager(llm);
contactsView.scrollToPosition(App.AllConnections.scrollPosition);
tagsView = getView().findViewById(R.id.allTags_recyclerView);
tagsView.setAdapter(adapter2);
lln = new LinearLayoutManager(main.getBaseContext(), LinearLayoutManager.HORIZONTAL, false);
tagsView.setLayoutManager(lln);
}
class Adapter_ContactListView extends RecyclerView.Adapter<Adapter_ContactListView.ViewHolder> implements Filterable {
List<Person_PersistentData> contactsFiltered;
Context context;
public Adapter_ContactListView(List<Person_PersistentData> list, Context context)
{
this.contactsFiltered = list;
this.context = context;
}
#Override
public Adapter_ContactListView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view_list, parent, false);
Adapter_ContactListView.ViewHolder pane = new Adapter_ContactListView.ViewHolder(v);
return pane;
}
#Override
public void onBindViewHolder(Adapter_ContactListView.ViewHolder pane, int position)
{
pane.setIsRecyclable(false);
final Person_PersistentData rec = contactsFiltered.get(position);
pane.nameView.setText(rec.personName + " (" + rec.personID + ")");
Uri imageUri = App.FSManager.getProfilePic(rec.personID);
if (imageUri != null) {pane.imageView.setImageURI(imageUri);}
else {pane.imageView.setImageResource(R.drawable.ico_60px);}
if (App.AllConnections.personSelectionStack.contains(rec.personID)) {pane.cv.setBackgroundColor(context.getResources().getColor(R.color.rgb_000_070_100));}
else
{pane.cv.setBackgroundColor(context.getResources().getColor(R.color.rgb_020_020_020));}
pane.cv.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view)
{
if(App.AllConnections.selectionMode)
{
App.Person_SelectionInput(rec.personID);
Adapter_ContactListView.this.notifyDataSetChanged();
}
else
{
App.PersonInfo.id = rec.personID;
main.startTask(T.personInfo);
}
}
});
pane.cv.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view)
{
App.Person_SelectionInput(rec.personID);
Adapter_ContactListView.this.notifyDataSetChanged();
return false;
}
});
//animate(holder);
}
#Override
public int getItemCount() {
//returns the number of elements the RecyclerView will display
return contactsFiltered.size();
}
#Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
#Override
public Filter getFilter() { ... }
#Override
public long getItemId(int position)
{
return position;
}
#Override
public int getItemViewType(int position) {
return position;
}
class ViewHolder extends RecyclerView.ViewHolder {
CardView cv;
TextView nameView;
ImageView imageView;
public ViewHolder(#NonNull View itemView)
{
super(itemView);
cv = itemView.findViewById(R.id.cardView);
nameView = itemView.findViewById(R.id.name);
imageView = itemView.findViewById(R.id.imageViewZ);
}
}
}
}
Question
So 'setIsRecyclable(False)' is supposed to prevent recycling of views and this should be causing more memory usage. But instead it is showing the opposite behavior. Also i think the app will surely crash if it has to handle an even larger list without using setIsRecyclable(false). Why is this happening ?

getItemId(int) and getItemViewType(int) should NEVER return position itself, you're violating recyclerview contract by forcing it to create new viewholders for every single position intead of re-using existing views.
This is the cause of your issue - every position has unique itemViewType so they start to fill up recycledViewPool very rapidly since they're only being inserted and never being taken out of it. setIsRecyclable(False) circumvents the issue by not putting them in recyclerViewPool but that doesn't fix the problem of lack of view recycling.
Just delete getItemId and getItemViewType overrides because you're not using them properly.

Shared Element Transition is not exiting properly

I have fragment from which I'm launching activity with shared element transition that has viewpager in it, the enter transition works fine but when i scroll in view pager and finish transition the shared image comes from left side which is not desired it should reposition itself to where it was launched, here is my code:
Intent myIntent = new Intent(getActivity(), EnlargeActivity.class);
ActivityOptionsCompat options = ActivityOptionsCompat.
makeSceneTransitionAnimation(getActivity(),
imageView,
ViewCompat.getTransitionName(imageView));
startActivity(myIntent, options.toBundle());
I'm updating view and its name in activity that contains viewpager when finishing activity, but its going with blink:
public void finishAfterTransition() {
setEnterSharedElementCallback(new SharedElementCallback() {
#Override
public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
// Clear all current shared views and names
names.clear();
sharedElements.clear();
ViewGroup viewGroup = (ViewGroup) viewPagerDetail.getAdapter()
.instantiateItem(viewPagerDetail, viewPagerDetail.getCurrentItem());
if (viewGroup == null) {
return;
}
// Map the first shared element name to the child ImageView.
sharedElements.put(viewGroup.findViewById(R.id.img).getTransitionName(), viewGroup.findViewById(R.id.img));
// setExitSharedElementCallback((SharedElementCallback) this);
}
});
super.finishAfterTransition();

Basically, Android start the transition with your pre-defined View and transitionName and automatically use the same properties for the return transition. When you change your focused View in ViewPager, Android doesn't know about that and keep the transition on the previous one on its way back. So you need to inform Android about the changes:
Remap the transition properties: Use setEnterSharedElementCallback to change the transitionName and View to the new one before returning from Activity2.
Wait for the Activity1 to finish rendering addOnPreDrawListener.
It's a bit complex in the final implementation. But you can look at my sample code https://github.com/tamhuynhit/PhotoGallery. I try to implement the shared-element-transition from many simple to complex sections.
Your problem appeared from Level 3 and solved in Level 4.
I am writing a tutorial about this but it's not in English so hope the code can help
UPDATE 1: Work flow
Here is how I implement it in my code:
Override finishAfterTransition in Activity2 and call setEnterSharedElementCallback method to re-map the current selected item in ViewPager. Also, call setResult to pass the new selected index back to previous activity here.
#Override
#TargetApi(Build.VERSION_CODES.LOLLIPOP)
public void finishAfterTransition() {
setEnterSharedElementCallback(new SharedElementCallback() {
#Override
public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
View selectedView = getSelectedView();
if (selectedView == null)
return;
// Clear all current shared views and names
names.clear();
sharedElements.clear();
// Store new selected view and name
String transitionName = ViewCompat.getTransitionName(selectedView);
names.add(transitionName);
sharedElements.put(transitionName, selectedView);
setExitSharedElementCallback((SharedElementCallback) null);
}
});
Intent intent = new Intent();
intent.putExtra(PHOTO_FOCUSED_INDEX, mCurrentIndex);
setResult(RESULT_PHOTO_CLOSED, intent);
super.finishAfterTransition();
}
Write a custom ShareElementCallback so I can set the callback before knowing which View is going to be used.
#TargetApi(Build.VERSION_CODES.LOLLIPOP)
private static class CustomSharedElementCallback extends SharedElementCallback {
private View mView;
/**
* Set the transtion View to the callback, this should be called before starting the transition so the View is not null
*/
public void setView(View view) {
mView = view;
}
#Override
public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
// Clear all current shared views and names
names.clear();
sharedElements.clear();
// Store new selected view and name
String transitionName = ViewCompat.getTransitionName(mView);
names.add(transitionName);
sharedElements.put(transitionName, mView);
}
}
Override onActivityReenter in Activity1, get the selected index from the result Intent. Set setExitSharedElementCallback to re-map new selected View when the transition begins.Call supportPostponeEnterTransition to delay a bit because your new View may not be rendered at this point. Use getViewTreeObserver().addOnPreDrawListener to listen for the layout changes, find the right View by the selected index and continue the transition supportStartPostponedEnterTransition.
#Override
#TargetApi(Build.VERSION_CODES.LOLLIPOP)
public void onActivityReenter(int resultCode, Intent data) {
if (resultCode != LevelFourFullPhotoActivity.RESULT_PHOTO_CLOSED || data == null)
return;
final int selectedIndex = data.getIntExtra(LevelFourFullPhotoActivity.PHOTO_FOCUSED_INDEX, -1);
if (selectedIndex == -1)
return;
// Scroll to the new selected view in case it's not currently visible on the screen
mPhotoList.scrollToPosition(selectedIndex);
final CustomSharedElementCallback callback = new CustomSharedElementCallback();
getActivity().setExitSharedElementCallback(callback);
// Listen for the transition end and clear all registered callback
getActivity().getWindow().getSharedElementExitTransition().addListener(new Transition.TransitionListener() {
#Override
public void onTransitionStart(Transition transition) {}
#Override
public void onTransitionPause(Transition transition) {}
#Override
public void onTransitionResume(Transition transition) {}
#Override
public void onTransitionEnd(Transition transition) {
removeCallback();
}
#Override
public void onTransitionCancel(Transition transition) {
removeCallback();
}
private void removeCallback() {
if (getActivity() != null) {
getActivity().getWindow().getSharedElementExitTransition().removeListener(this);
getActivity().setExitSharedElementCallback((SharedElementCallback) null);
}
}
});
// Pause transition until the selected view is fully drawn
getActivity().supportPostponeEnterTransition();
// Listen for the RecyclerView pre draw to make sure the selected view is visible,
// and findViewHolderForAdapterPosition will return a non null ViewHolder
mPhotoList.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
mPhotoList.getViewTreeObserver().removeOnPreDrawListener(this);
RecyclerView.ViewHolder holder = mPhotoList.findViewHolderForAdapterPosition(selectedIndex);
if (holder instanceof ViewHolder) {
callback.setView(((ViewHolder) holder).mPhotoImg);
}
// Continue the transition
getActivity().supportStartPostponedEnterTransition();
return true;
}
});
}
UPDATE 2: getSelectedItem
To get selected View from the ViewPager, don't use getChildAt or you get the wrong View, use findViewWithTag instead
In the PagerAdapter.instantiateItem, use position as tag for each View:
#Override
public View instantiateItem(ViewGroup container, int position) {
// Create the View
view.setTag(position)
// ...
}
Listen to onPageSelected event to get the selected index:
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
mSelectedIndex = position;
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
Call getSelectedView to get the current view by the selected index
private View getSelectedView() {
try {
return mPhotoViewPager.findViewWithTag(mSelectedIndex);
} catch (IndexOutOfBoundsException | NullPointerException ex) {
return null;
}
}

This is actually a default behavior, I was struggling SharedElementTransitions a lot, but I have nested fragments. I got my solution from an article (very recent article), it shows an implementation with a RecyclerView, which I assume you have. In short, the solution is to override onLayoutChange :
recyclerView.addOnLayoutChangeListener(
new OnLayoutChangeListener() {
#Override
public void onLayoutChange(View view,
int left,
int top,
int right,
int bottom,
int oldLeft,
int oldTop,
int oldRight,
int oldBottom) {
recyclerView.removeOnLayoutChangeListener(this);
final RecyclerView.LayoutManager layoutManager =
recyclerView.getLayoutManager();
View viewAtPosition =
layoutManager.findViewByPosition(MainActivity.currentPosition);
// Scroll to position if the view for the current position is null (not
// currently part of layout manager children), or it's not completely
// visible.
if (viewAtPosition == null
|| layoutManager.isViewPartiallyVisible(viewAtPosition, false, true)){
recyclerView.post(()
-> layoutManager.scrollToPosition(MainActivity.currentPosition));
}
}
});
Here is the article, and you will also find the project on GitHub.

What is notifyItemRangeChanged(0, this.data.size()); in this example and how does it work?

I understand how a ViewHolder's onBindViewHolder works, however I'm unclear about how notifyItemRangeChanged(0, this.data.size()); works in this example and what it does exactly.
The data that is supplied to this adapter is in Json format.
The adapter is below:
public class AdapterQuestion extends RecyclerView.Adapter<AdapterQuestion.ViewQuestion>{
private LayoutInflater mLayoutInflater;
//this is an arrayList of questionData objects
private ArrayList<QuestionData> data =new ArrayList<>();
//Created the layoutInflator
public AdapterQuestion(Context context){
//get from context
mLayoutInflater=LayoutInflater.from(context);
}
public void setBloglist(ArrayList<QuestionData> data){
this.data =data;
notifyItemRangeChanged(0, this.data.size());
}
#Override
public ViewQuestion onCreateViewHolder(ViewGroup parent, int viewType) {
//inflates the customQuestion view or converts it to java code
View view= mLayoutInflater.inflate(R.layout.customquestion, null);
//We now want to convert the View into a ViewQuestion, view Question takes
//a view so we pass the view into view question and then return it.
ViewQuestion holder=new ViewQuestion(view);
return holder;
}
//ViewGroup parent and ViewType are not being assigned.
#Override
public void onBindViewHolder(ViewQuestion holder, int position) {
//here we need to bind the data to our view, there is currently no Data!
//We need to get the data from our JSON
//Parameters is a ViewHolder and a Position
//This gives us the current information object from the whole arraylist
//data.get(position) data is the arraylist and we are getting the current position or index;
//That current obj is of Type QuestionData
QuestionData currentObj= data.get(position);
//we are accessing the Inflated view, or saved view with holder
//holder.answerText is the textView in holder. We are then taking that current object
//We are getting the text of the current object and setting it to the AnswerText view
holder.answerText.setText(currentObj.getMtext());
holder.answerId.setText(currentObj.getId());
holder.mVotes.setText(currentObj.getVotes());
holder.mLikeButton.setTag(currentObj);
}
#Override
public int getItemCount() {
return data.size();
}
public class ViewQuestion extends RecyclerView.ViewHolder{
//once we create it once the reclycer view will automatically recycle it
private TextView answerText;
private TextView answerId;
private TextView mVotes;
private LikeButton mLikeButton;
public ViewQuestion (View itemView){
super(itemView);
//here we are finding the views by their ID
answerText=(TextView)itemView.findViewById(R.id.answerText);
answerId=(TextView)itemView.findViewById(R.id.answerId);
mVotes=(TextView)itemView.findViewById(R.id.VoteTextView);
mLikeButton= (LikeButton)itemView.findViewById(R.id.heart_buttons);
mLikeButton.setOnLikeListener(new OnLikeListener() {
#Override
public void liked(LikeButton likeButton) {
Voting vote = new Voting();
vote.onUpVote(convertToString(),
getAdapterPosition(),ViewQuestion.this);
System.out.print("Adapter Position"+getAdapterPosition());
}
#Override
public void unLiked(LikeButton likeButton) {
Voting onDown=new Voting();
onDown.onDownVote(convertToString(),
getAdapterPosition(), ViewQuestion.this);
}
});
}
public String getVoteView(){
String voteView=mVotes.getText().toString();
return voteView;
}
public String convertToString(){
String converted=answerId.getText().toString();
return converted;
}
public int convertToInt(){
String converted=answerId.getText().toString();
int ConvertedInt=Integer.parseInt(converted);
return ConvertedInt;
}
}
}

When the data that is to be set in RecyclerView is changed, the Adapter needs to get notified of the data change so that it can change the data in recyclerview.
The method
notifyItemRangedChanged(fromIndex,toIndex);
is used to notify the adapter that some set of data is changed among the whole data and it tells the adapter that adapter should refresh the data and reload it into the recyclerView starting from fromIndex to toIndex as passed into the method .
use this method if you have multiple data changed but not all , those changed data also are in cluster so that you can say from 5th to 10th index data are changed .
If all data are changed call :
notifyDataSetChanged();
if only one dataItem is changed then call :
notifyItemChanged(dataPosition);

Using notifyItemRangeChanged(0, this.data.size()) it’s bad practice.
Best way is using notifyItemChanged or notifyItemRangeChanged with payload.
Payload - optional parameter (key). That give you opportunity to check what kind of update do you need.
public void onBindViewHolder(/*...*/, List payloads) {
if (payloads.isEmpty()) {
setText(holder, position);
downloadBitmap(holder, position);
} else if (payloads.contains(SET_ONLY_TEXT)){
setText(holder, position);
}
}
In this example payloads used for checking when adapter should update only the text.

in your case you are not doing it(notifyItemRangeChanged) right as you might as well can call notifyDataSetChanged(); because you are telling the adapter that the entire list has changed and not specific position.

Android ViewPager: Destroy Fragment on Slide?

I am basically playing an animation on each fragment of the view pager. The animation plays when the user slides to the specific fragment. However, certain fragments don't play the animation the second time I visit them. That's because the view pager keeps them in memory.
I need to destroy each fragment after the user slides to another fragment. This way, the animations play every time I revisit those fragments.
Main View:
pager = (ViewPager) findViewById(R.id.guidepager);
mAdapter = new NewUserGuideAdapter(getSupportFragmentManager());
pager.setAdapter(mAdapter);
pager.setOffscreenPageLimit(0); //Tried this too. Didnt work
Fragment:
public class NewUserPage_Two extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_new_user_page__two, container, false);
//Play animation, etc
Animation animation_1 = AnimationUtils.loadAnimation(NewUserPage_Two.this.getActivity(), R.anim.abc_slide_in_bottom);
person1.setAnimation(animation_1);
return rootView;
}
Adapter:
public class NewUserGuideAdapter extends FragmentPagerAdapter {
public NewUserGuideAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new NewUserPage_One();
case 1:
return new NewUserPage_Two();
case 2:
return new NewUserPage_Three();
case 3:
return new NewUserPage_One();
case 4:
return new NewUserPage_One();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 5;
}
}
How can I amend my code guys?

ViewPager provide a method mViewPager.setOffscreenPageLimit(0);
Set the number of pages that should be retained to either side of the current page in the view hierarchy in an idle state. Pages beyond this limit will be recreated from the adapter when needed.

Try this inside the fragment:
((BaseAdapter) *YourContainer*.getAdapter()).notifyDataSetChanged();
You can refer to: Refresh Current Fragment (ListView Data) remaining in the same activity

public void setOffscreenPageLimit(int limit) {
if (limit < DEFAULT_OFFSCREEN_PAGES) {
Log.w(TAG, "Requested offscreen page limit " + limit + " too small; defaulting to " +
DEFAULT_OFFSCREEN_PAGES);
limit = DEFAULT_OFFSCREEN_PAGES;
}
if (limit != mOffscreenPageLimit) {
mOffscreenPageLimit = limit;
populate();
}
}
That's the method body,DEFAULT_OFFSCREEN_PAGES=1by the way.I think google add this limits cause you need at least the 2 views between current item while you are sliding.
You can try using addOnPageChangeListener() and start your animation on onPageSelected.

RecyclerView is drawn before its data set is updated

I have a fragment in which I have a RecyclerView:
public class AlarmListFragment extends Fragment{
public AlarmListAdapter alarmListAdapter;
RecyclerView recyclerViewAlarms;
public AlarmListFragment() { }
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_alarm_list, container, false);
recyclerViewAlarms = (RecyclerView) rootView.findViewById(R.id.fragment_alarm_list_card_list);
recyclerViewAlarms.setHasFixedSize(true); // performance!
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
recyclerViewAlarms.setLayoutManager(llm);
alarmListAdapter = new AlarmListAdapter(getActivity());
recyclerViewAlarms.setAdapter(alarmListAdapter);
return rootView;
}
It uses the following Adapter:
public class AlarmListAdapter extends RecyclerView.Adapter<AlarmListViewHolder> {
private List<AlarmModel> alarmModelDataSet;
private Context context;
public AlarmListAdapter(Context context) {
this.alarmModelDataSet = AlarmModel.listAll(AlarmModel.class);
this.context = context;
}
#Override
public AlarmListViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
View view = inflater.inflate(R.layout.alarm_list_card, parent, false);
return new AlarmListViewHolder(view);
}
#Override
public int getItemCount() {
return (int) AlarmModel.count(AlarmModel.class, null, null);
}
#Override
public void onBindViewHolder(AlarmListViewHolder holder, int position) {
// todo wait here until alarmModel is added to DataSet
AlarmModel alarmModel = alarmModelDataSet.get(position);
*** update GUI stuff ***
if (alarmModel.isEnabled()) {
*** update GUI stuff ***
}
if (alarmModel.isRepeatWeekly()) {
*** update GUI stuff ***
} else {
*** update GUI stuff ***
}
if (!alarmModel.isEnabled()){
*** update GUI stuff ***
}
}
public List<AlarmModel> getDataSet(){
return alarmModelDataSet;
}
public int getIndex(AlarmModel alarmModel){
for (AlarmModel _item : alarmModelDataSet){
if (_item.getId().equals(alarmModel.getId())){
return alarmModelDataSet.indexOf(_item);
}
}
return -1;
}
public void addOrUpdateAlarm(AlarmModel alarmModel){
int position = getIndex(alarmModel);
if (position >= 0) {
updateAlarm(alarmModel, position);
} else {
addAlarm(alarmModel);
}
}
private void addAlarm(AlarmModel alarmModel){
alarmModelDataSet.add(alarmModel);
notifyItemInserted(alarmModelDataSet.size() - 1);
}
private void updateAlarm(AlarmModel alarmModel, int position){
alarmModelDataSet.set(getIndex(alarmModel), alarmModel);
notifyItemChanged(position);
}
public void deleteAlarm(AlarmModel alarmModel) {
alarmModel.setIsEnabled(false);
AlarmManagerBroadcastReceiver.setAlarms(context);
int position = getIndex(alarmModel);
alarmModelDataSet.remove(position); // deletes out of class internal List
notifyItemRemoved(position); // notifies list fragment of deletion
}
public void enableOrDisableAlarm(int position){
AlarmModel alarmModel = alarmModelDataSet.get(position);
alarmModel.setIsEnabled(!alarmModel.isEnabled());
notifyItemChanged(position);
}
Every alarmModel is saved in a database which is working fine thus I removed the code about the database.
The fragment from the first code snippet uses startActivityForResult to open up an activity that allows the creation of a new alarm that is stored in another alarmModel. This new alarmModel is saved to the data base and its ID is returned to my fragment by this code
Intent intent = new Intent();
intent.putExtra("id", alarmDetails.getId());
intent.putExtra("delete", false);
setResult(RESULT_OK, intent);
supportFinishAfterTransition();
This result is received by the onActivityResult method of the fragment:
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK && requestCode == REQUEST_CODE_ADD_ALARM_ID) {
long id = data.getLongExtra("id", -7777);
if (data.getBooleanExtra("delete", false)) { // delete
alarmListAdapter.deleteAlarm(AlarmModel.findById(AlarmModel.class, id));
} else { // add or update
alarmListAdapter.addOrUpdateAlarm(AlarmModel.findById(AlarmModel.class, id));
}
}
}
After all this code I finally am able to describe my problem:
Before the code even reaches the addOrUpdate method, the adapter's onBindViewHolder method is called and produces an IndexOutOfBoundsException because AlarmModel alarmModel = alarmModelDataSet.get(position); the just added alarmModel wants to get drawn but is not yet added to the DataSet.
Everything works fine (although the app becomes pretty slow) when the RecyclerView has ~10+ items since onBindViewHolder is called for every other item first and after calculating 9 other items the addOrUpdate method has finished.
Is there a fatal mistake I made or a method I did not find yet, which could help me? I thought about using two threads and letting one wait until the other one has finished but am unsure how to do that since I allready know that you should never block the Ui-Thread.
Edit 1
In an attempt to make the add, update and delete method in the adapter static I removed the List alarmModelDataSetcompletely and queried the data base every time instead. Although my initial plan did not work out, I noticed that it solved my problem by making the methods so slow that everything worked fine again. But since this is not a real solution but simply bad coding that works slowly I am not really satisfied with it...
Thanks to everybody reading this long question/problem
Tafelbomber