pageState and viewModelState is null on Page Navigation in UWP - xaml

I am using Prism 6 with UWP. I have a button in MainPage.xaml which redirect to DashboardPage.xaml. In DashboardPage, I am saving the view state in DashboardPage.xaml.cs :
protected override void SaveState(Dictionary<string, object> pageState)
{
base.SaveState(pageState);
pageState["viewState"] = 123;
}
and saving view model state in DashboardPageViewModel.cs :
public override void OnNavigatingFrom(NavigatingFromEventArgs e, Dictionary<string, object> viewModelState, bool suspending)
{
base.OnNavigatingFrom(e, viewModelState, suspending);
}
[RestorableState]
public string Name
{
get { return _name; }
set { SetProperty(ref _name, value); }
}
By pressing back button from topbar, I went back to MainPage.xaml. After that, when I navigate to DashboardPage.xaml again, I found that view state and view model states are being null. Which means, in the below code of DashboardPage.xaml.cs
protected override void LoadState(object navigationParameter, Dictionary<string, object> pageState)
{
if (pageState == null)
{
return;
}
base.LoadState(navigationParameter, pageState);
if (pageState.ContainsKey("viewState"))
{
var data = pageState["viewState"].ToString();
}
}
pageState is found null.
And, for view model state in DashboardPageViewModel.cs :
public async override void OnNavigatedTo(NavigatedToEventArgs e, Dictionary<string, object> viewModelState)
{
base.OnNavigatedTo(e, viewModelState);
}
viewModelState is null

By pressing back button from topbar, I went back to MainPage.xaml. After that, when I navigate to DashboardPage.xaml again, I found that view state and view model states are being null.
From your posted project. I found that you use NavigationService.Navigate to navigate to DashboardPage. It's right at first time, but after you navigating back to MainPage and again navigate back to DashboardPage. You are also using the NavigationService.Navigate API.
I downloaded Prism's Source Codes and found where the LoadState is called:
protected override void OnNavigatedTo(NavigationEventArgs navigationEventArgs)
{
...
if (navigationEventArgs.NavigationMode == NavigationMode.New)
{
var nextPageKey = _pageKey;
int nextPageIndex = frameFacade.BackStackDepth;
while (frameState.Remove(nextPageKey))
{
nextPageIndex++;
nextPageKey = "Page-" + nextPageIndex;
}
// Pass the navigation parameter to the new page
LoadState(navigationEventArgs.Parameter, null);
}
else
{
LoadState(navigationEventArgs.Parameter, (Dictionary<String, Object>)frameState[_pageKey]);
}
}
As you can see, the LoadState is called inside OnNavigatedTo and PageState is passed as argument on condition that the NavigationMode is not New. For ViewModelState it is the similar situation. And for your case, everytime navigating to a page through NavigationService.Navigate will create a totally new page, which means NavigationMode=NavigationMode.New. Therefore PageState and ViewModelState are null.
From the NavigationMode document we can see the NavigationMode.Forward fits your requirement.
So, to fix the problem. The only thing that needs to be done is to modify the OnPageChange method in MainPageViewModel.cs like codes below:
private void OnPageChange()
{
if (_navigationService.CanGoForward())
{
_navigationService.GoForward();
}
else
{
_navigationService.Navigate("Dashboard", null);
}
}

Related

change item color on click in recyclerview android

I am trying to change the color of the items on click when the action mode is active. The problem is that e.g if there are five items in a recyclerview and you click one, scroll down and select sixth item and destroy the action mode. The next time you start selecting, that sixth item has automatically changed its color without you selecting it. I don't know why it is happening.
public static List<ModelClass> items = new ArrayList<>();
boolean isSelectMode = false;
boolean isActionModeEnabled = false;
public static List<ModelClass> selectList = new ArrayList<>();
#Override
public void onBindViewHolder(#NonNull MyAdapter.MyViewHolder holder, int
position) {
holder.bind(items.get(position));
ModelClass modelClass = items.get(position);
if (modelClass.isChecked() && isActionModeEnabled){
holder.row.setBackgroundColor(Color.GREEN);
modelClass.setChecked(true);
} else {
holder.row.setBackgroundColor(Color.TRANSPARENT);
modelClass.setChecked(false);
}
}
public class MyViewHolder extends RecyclerView.ViewHolder{
public MyViewHolder(#NonNull View itemView) {
super(itemView);
row = itemView.findViewById(R.id.row);
public void bind(ModelClass model) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (isActionModeEnabled) {
isSelectMode = true;
s = items.get(getAdapterPosition());
if (!selectList.contains(s)){
selectList.add(s);
row.setBackgroundColor(Color.GREEN);
model.setChecked(true);
} else {
selectList.remove(s);
row.setBackgroundColor(Color.TRANSPARENT);
model.setChecked(false);
}
}
});
}
The problem is going to be in your view holder binding:
if (modelClass.isChecked() && isActionModeEnabled){
holder.row.setBackgroundColor(Color.GREEN);
modelClass.setChecked(true);
} else {
holder.row.setBackgroundColor(Color.TRANSPARENT);
modelClass.setChecked(false);
}
Remember that view holders are reused. That means that they will retain their internal state unless you change them. Your item list will also remember its state. Make sure you cover all the possible states of the item list and the reused view holders in the code above: You are probably missing a combination.
I recommend that you set a break point in the code above to make sure it is doing what you want. It should become obvious to you once you take a closer look.

Xamarin.Android how to remember the position of items in a recyclerview

I have a recyclerview set up in xamarin.android as per the code in this link
https://www.appliedcodelog.com/2019/08/reorder-list-items-by-drag-and-drop-in.html
My question is, how can I remember the position of these items when the app is restarted etc. When the user adds items they are inserted at adapter position 0,1,2,3 etc but when they close the app and come back in, it is not always in the same order.
The user can also rearrange by drag and drop so this seems to add even more confusion!
Currently I have the items in the recyclerview being saved by converting the list to Json and loading when the app opens again but as I said, the items aren't always in the same order as before the app was closed.
Can anyone advise the best way to do this? I have tried to add the item name and position number to a list converting to json then trying to insert the item at the saved position index but can't get it to work..
Thanks
Do you want to achieve the result like following GIF?
You can use PreferenceManager to store position of items(Before store data, I will Serialize data) in a recyclerview.
You can override OnPause() method, this method will be executed when application is background or app is killed. So we can store the position and data in this method.Here is code about ReOrderActivity
[Activity(Label = "ReOrderList")]
public class ReOrderActivity : Activity, IOnStartDragListener
{
private ItemTouchHelper _mItemTouchHelper;
public static ObservableCollection<string> ResourceList;
private RecyclerView _resourceReorderRecyclerView;
ReOrderAdapters resourceAdapter;
ISharedPreferences prefs;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.ReOrderLayout);
prefs = PreferenceManager.GetDefaultSharedPreferences(this);
GetCollection();
resourceAdapter = new ReOrderAdapters(ResourceList, this);
// Initialize the recycler view.
_resourceReorderRecyclerView = FindViewById<RecyclerView>(Resource.Id.ResourceReorderRecyclerView);
Button mDone = FindViewById<Button>(Resource.Id.mDone);
mDone.Click += MDone_Click;
_resourceReorderRecyclerView.SetLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.Vertical, false));
_resourceReorderRecyclerView.SetAdapter(resourceAdapter);
_resourceReorderRecyclerView.HasFixedSize = true;
ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(resourceAdapter);
_mItemTouchHelper = new ItemTouchHelper(callback);
_mItemTouchHelper.AttachToRecyclerView(_resourceReorderRecyclerView);
}
protected override void OnPause()
{
base.OnPause();
string ConvertData = JsonConvert.SerializeObject(ResourceList);
ISharedPreferencesEditor editor = prefs.Edit();
editor.PutString("ObservableCollection_ConvertData", ConvertData);
// editor.Commit(); // applies changes synchronously on older APIs
editor.Apply(); // applies changes asynchronously on newer APIs
}
private void MDone_Click(object sender, System.EventArgs e)
{
resourceAdapter.AddItem("Add item");
}
public void OnStartDrag(RecyclerView.ViewHolder viewHolder)
{
_mItemTouchHelper.StartDrag(viewHolder);
}
//Added sample data record here
public void GetCollection()
{
//ISharedPreferencesEditor editor = prefs.Edit();
//editor.PutString("ObservableCollection_ConvertData", "");
//editor.Apply();
string ConvertData = prefs.GetString("ObservableCollection_ConvertData","");
if(string.IsNullOrEmpty(ConvertData))
{
ResourceList = new ObservableCollection<string>();
ResourceList.Add("OnPause()");
ResourceList.Add("OnStart()");
ResourceList.Add("OnCreate()");
}
else
{
ResourceList= JsonConvert.DeserializeObject<ObservableCollection<string>>(ConvertData);
}
//var or= ResourceList.ToString();
}
}
}
You can download my demo
https://drive.google.com/file/d/1mQTKf3rlcIVnf2N97amrqtnrSCRk-8ZW/view?usp=sharing

How to check if an application is it's first run or not in xamarin crosspaltform

I want to show some pages in the first time app is installed, and the next time when I open the app show some other pages.
I tried this code
protected override void OnStart()
{
if (Application.Current.Properties.ContainsKey("id"))
{
MainPage = new NavigationPage(new Page2());
}
else
{
Application.Current.Properties["id"] = 2;
MainPage = new NavigationPage(new Page1());
}
}
The values in the Properties dictionary are only stored when the app goes to sleep
For a cross-platform approach, you can use the Settings Plugin
Then you can create a boolean property, for example, DidOpenOnce, and if it is false, show your initial welcome page or whatever. Then afterwards, set it to true.
protected void checkApplicationInstallState()
{
//retreive
var prefs = Application.Context.GetSharedPreferences("MyApp", FileCreationMode.Private);
var somePref = prefs.GetBool("IsApplicationOpenedForOnce", null);
if (!somePref) {
// Your Application is opened for the very first time. Now change the value to true as you have now opened the app so next time opening this application should get a true value.
var prefEditor = prefs.Edit();
prefEditor.PutBool(true, "IsApplicationOpenedForOnce");
prefEditor.Commit();
}
}
public MainPage()
{
InitializeComponent();
if (Application.Current.Properties.ContainsKey("FirstUse"))
{
//Do things when it's NOT the first use...
loadinit();
}
else
{
Application.Current.Properties["FirstUse"] = false;
//Do things when it IS the first use...
}
}
public async void loadinit()
{
await Navigation.PushAsync(new LoadPage());
}

Is it somehow possible to have two master views and one detail view?

If I have for example one master view on the left and one in the middle, each showing oder Java Beans/POJOs, can I use a shared detail view that somehow listens to the active beans of each view and then displays the currently selected one in more detail? A one to one relation is quite easy to manage by using your Context library.
#ViewDocking(areaId ="left", position=1, displayName="Profiles", menuEntry = #WindowMenuEntry(path = "", position=0), accelerator="Shortcut+1")
public class ProfileListView extends BorderPane implements LocalContextProvider {
private final SimpleContextContent content = new SimpleContextContent();
private final SimpleContext context = new SimpleContext(content);
#FXML
private ListView<Profile> listview;
public ProfileListView() {
load();
// add some profiles
listview.getItems().add(new Profile("Profile1"));
listview.getItems().add(new Profile("Profile2"));
listview.getItems().add(new Profile("Profile3"));
// setup selection listener
listview.getSelectionModel().selectedItemProperty().addListener((value, oldProfile, newProfile) -> {
// set active profile and remove old one
content.remove(oldProfile);
content.add(newProfile);
});
// setup double click listener
configureClickListener();
}
private Profile getSelectedProfile() {
return listview.getSelectionModel().getSelectedItem();
}
private void configureClickListener() {
listview.setOnMouseClicked(event -> {
// check if it was a double click
if(event.getClickCount() == 2) {
System.out.println(getSelectedProfile());
// inject into editor pane
// calls the procedure to create a tab in the center area...
}
});
}
private void load() {
FXMLLoaders.loadRoot(this);
}
#Override
public Context getLocalContext() {
return context;
}
}
This is one master view holding a list view of items.
The other one would be the same, docking to the right as another tab and holding POJOs of type 'Action'.
The detail view is here:
#ViewDocking(areaId = "right", displayName = "Properties", accelerator = "Shortcut+2", menuEntry = #WindowMenuEntry(path = "", position = 0), position = 1)
public class ProfilePropertiesView extends BorderPane implements LocalContextProvider, ActiveContextSensitive {
private Context activeContext;
private SimpleContextContent content = new SimpleContextContent();
private SimpleContext context = new SimpleContext(content);
private Profile profile;
private IWindowService service = new NullWindowService();
#FXML
private PropertySheet propertysheet;
public ProfilePropertiesView() {
load();
// retrieve framework service, TODO: use tracker
BundleContext ctx = FrameworkUtil.getBundle(getClass()).getBundleContext();
service = ctx.getService(ctx.getServiceReference(IWindowService.class));
// initialize callback
service.addCallback(title -> {
System.out.println("callback called " + title);
// update the property sheet ui by re-creating the items list
// updateUI();
// we can safely return null
return null;
});
// configure editor factory so the user is able to use a combobox
propertysheet.setPropertyEditorFactory(new CustomPropertyEditorFactory(service));
}
private void load() {
FXMLLoaders.loadRoot(this);
}
#Override
public Context getLocalContext() {
return context;
}
private void contextChanged() {
// find profile information
Profile found = activeContext.find(Profile.class);
// if the found profile is null, ignore it
if (found != null) {
// reset if profile is valid
if (profile != null) {
reset();
}
// create reference and register
profile = found;
register();
}
}
private void register() {
// retrieve observablelist of bean properties if some profile is selected
if(profile != null) {
ObservableList<Item> items = createDetailedList(profile);
propertysheet.getItems().setAll(items);
}
}
private void updateUI() {
// clear property elements and re-create them
reset();
// re-create items
ObservableList<Item> items = createDetailedList(profile);
propertysheet.getItems().addAll(items);
}
private ObservableList<Item> createDetailedList(Object bean) {
ObservableList<Item> list = FXCollections.observableArrayList();
try {
BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass(), Object.class);
Arrays.stream(beanInfo.getPropertyDescriptors()).map(pd -> new DetailedBeanProperty(bean, pd)).forEach(list::add);
} catch (IntrospectionException e) {
e.printStackTrace();
}
return list;
}
private void reset() {
propertysheet.getItems().clear();
}
#Override
public void setActiveContext(Context activeContext) {
this.activeContext = activeContext;
this.activeContext.addContextListener(Profile.class, event -> contextChanged());
// trigger change
contextChanged();
}
}
The current ProfilePropertiesView is just configured to display the properties of the selected profile. I want it to be able to display the current information of the last selected POJO in the UI. That means that if the user selected a Profile from the ListView, that profile should be displayed in the properties view. If he selected an Action from the Table (which is displayed in the center), the properties of the Action should be displayed.
Do I just need to register a new ContextListener for the Action.class
POJO and then call a method to populate the PropertiesView? I was
unsure if this is the right solution...
Yes, just add another ContextListener to the activeContext for every POJO type you want to observe.
Also note that in the constructor of views it's better to use a ServiceTracker instead of looking for the service via BundleContext as the service might not be available yet, depending on the order the bundles are loaded.
You can find a sample which uses a ServiceTracker here: https://stackoverflow.com/a/35974498/506855

Recycler View: Inconsistency detected. Invalid view holder adapter positionViewHolder

Recycler View Inconsistency Detected error, coming while scrolling fast or scrolling while loading more items..
FATAL EXCEPTION: main
Process: com.pratap.endlessrecyclerview, PID: 21997
java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder{56a082c position=40 id=-1, oldPos=39, pLpos:39 scrap [attachedScrap] tmpDetached no parent}
at android.support.v7.widget.RecyclerView$Recycler.validateViewHolderForOffsetPosition(RecyclerView.java:4251)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4382)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4363)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1961)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1370)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1333)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:562)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2864)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1445)
at android.support.v7.widget.RecyclerView.access$400(RecyclerView.java:144)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:282)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:603)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
Adapter
public class DataAdapter extends RecyclerView.Adapter {
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private List<Feed> mFeed;
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public DataAdapter(List<Feed> feeds, RecyclerView recyclerView) {
mFeed = feeds;
if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView
.getLayoutManager();
recyclerView
.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView,
int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = linearLayoutManager.getItemCount();
lastVisibleItem = linearLayoutManager
.findLastVisibleItemPosition();
if (!loading
&& totalItemCount <= (lastVisibleItem + visibleThreshold)) {
// End has been reached
// Do something
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
#Override
public int getItemViewType(int position) {
return mFeed.get(position) == null ? VIEW_PROG : VIEW_ITEM;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
RecyclerView.ViewHolder vh;
if (viewType == VIEW_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.list_row, parent, false);
vh = new StudentViewHolder(v);
}
else {
View v = LayoutInflater.from(parent.getContext()).inflate(
R.layout.progress_item, parent, false);
vh = new ProgressViewHolder(v);
}
return vh;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof StudentViewHolder) {
Feed singleStudent= (Feed) mFeed.get(position);
((StudentViewHolder) holder).tvName.setText(singleStudent.getTitle());
((StudentViewHolder) holder).student= singleStudent;
} else {
ProgressViewHolder.PROGRESS_BAR.setIndeterminate(true);
}
}
public void setLoaded() {
loading = false;
}
public void addFeed(Feed feed) {
mFeed.add(feed);
//mFeed.addAll(0, (Collection<? extends Feed>) feed);
notifyItemInserted(mFeed.size());
//notifyItemRangeInserted(0,mFeed.size());
notifyDataSetChanged();
//notifyItemInserted(mFeed.size());
//setLoaded();
//notifyItemInserted(mFeed.size());
}
public void removeAll(){
mFeed.clear();
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return mFeed.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
public static class StudentViewHolder extends RecyclerView.ViewHolder {
public TextView tvName;
public Feed student;
public StudentViewHolder(View v) {
super(v);
tvName = (TextView) v.findViewById(R.id.tvName);
//tvEmailId = (TextView) v.findViewById(R.id.tvEmailId);
}
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
//public ProgressBar progressBar;
public static ProgressBar PROGRESS_BAR;
public ProgressViewHolder(View v) {
super(v);
PROGRESS_BAR = (ProgressBar) v.findViewById(R.id.progressBar1);
// progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
}
}
}
Activity
public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
private Toolbar toolbar;
private TextView tvEmptyView;
private RecyclerView mRecyclerView;
private DataAdapter mAdapter;
private LinearLayoutManager mLayoutManager;
private RestManager mManager;
private List<Feed> mFeed;
SwipeRefreshLayout mSwipeRefreshLayout;
protected Handler handler;
private int currentPage=1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
tvEmptyView = (TextView) findViewById(R.id.empty_view);
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
mSwipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);
mSwipeRefreshLayout.setOnRefreshListener(this);
//studentList = new ArrayList<Student>();
mFeed = new ArrayList<Feed>();
handler = new Handler();
if (toolbar != null) {
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("Android Students");
}
mManager = new RestManager();
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(this);
// use a linear layout manager
mRecyclerView.setLayoutManager(mLayoutManager);
// create an Object for Adapter
mAdapter = new DataAdapter(mFeed,mRecyclerView);
// set the adapter object to the Recyclerview
mRecyclerView.setAdapter(mAdapter);
// mAdapter.notifyDataSetChanged();
loadData(false);
// if (mFeed.isEmpty()) {
// mRecyclerView.setVisibility(View.GONE);
// tvEmptyView.setVisibility(View.VISIBLE);
//
// } else {
// mRecyclerView.setVisibility(View.VISIBLE);
// tvEmptyView.setVisibility(View.GONE);
// }
mAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
#Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
mFeed.add(null);
mAdapter.notifyItemInserted(mFeed.size() - 1);
handler.postDelayed(new Runnable() {
#Override
public void run() {
// remove progress item
mFeed.remove(mFeed.size() - 1);
// mAdapter.notifyItemRemoved(mFeed.size());
//add items one by one
int start = mFeed.size();
currentPage++;
Log.d("CurrentPage", String.valueOf(currentPage));
Call<Results> listCall = mManager.getFeedApi().getAllFeeds(1);
listCall.enqueue(new Callback<Results>() {
#Override
public void onResponse(Call<Results> call, Response<Results> response) {
mSwipeRefreshLayout.setRefreshing(false);
if (response.isSuccess()) {
if (response.body() != null) {
Results feedList = response.body();
// List<Results> newUsers = response.body();
Log.d("Retrofut", String.valueOf(feedList));
for (int i = 0; i < feedList.results.size(); i++) {
Feed feed = feedList.results.get(i);
// mFeed.add(feed);
mAdapter.addFeed(feed);
// mAdapter.notifyDataSetChanged();
//mAdapter.notifyItemInserted(mFeed.size());
}
// mAdapter.notifyDataSetChanged();
}
}
}
#Override
public void onFailure(Call<Results> call, Throwable t) {
Log.d("Retrofut", "Error");
mFeed.remove(mFeed.size() - 1);
mAdapter.notifyItemRemoved(mFeed.size());
mAdapter.setLoaded();
mSwipeRefreshLayout.setRefreshing(false);
}
});
// for (int i = 1; i <= 20; i++) {
// studentList.add(new Student("Student " + i, "androidstudent" + i + "#gmail.com"));
//
// }
mAdapter.setLoaded();
//or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
}
}, 2000);
}
});
}
// load initial data
private void loadData(final boolean removePreData) {
Call<Results> listCall = mManager.getFeedApi().getAllFeeds(1);
listCall.enqueue(new Callback<Results>() {
#Override
public void onResponse(Call<Results> call, Response<Results> response) {
if (response.isSuccess()) {
if (response.body() != null) {
// if(removePreData) mAdapter.removeAll();
Results feedList = response.body();
Log.d("Retrofut", String.valueOf(feedList));
for (int i = 0; i < feedList.results.size(); i++) {
Feed feed = feedList.results.get(i);
// mFeed.add(feed);
//mAdapter.notifyDataSetChanged();
mAdapter.addFeed(feed);
}
mSwipeRefreshLayout.setRefreshing(false);
}
}
}
#Override
public void onFailure(Call<Results> call, Throwable t) {
Log.d("Retrofut", String.valueOf(t));
mFeed.remove(mFeed.size() - 1);
mAdapter.notifyItemRemoved(mFeed.size());
mAdapter.setLoaded();
mSwipeRefreshLayout.setRefreshing(false);
}
}
);
// for (int i = 1; i <= 20; i++) {
// studentList.add(new Student("Student " + i, "androidstudent" + i + "#gmail.com"));
//
// }
mSwipeRefreshLayout.setRefreshing(true);
}
#Override
public void onRefresh() {
mFeed.clear();
mAdapter.notifyDataSetChanged();
loadData(true);
currentPage=1;
}
}
put this line along with setting recyclerView. issue was fixed by
setting ItemAnimator to null for RecyclerView.
in kotlin
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.itemAnimator = null
in java
recyclerView.setItemAnimator(null);
It looks similar with known android bug
There are quite ugly, but working approach
public class WrapContentLinearLayoutManager extends LinearLayoutManager {
//... constructor
#Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
try {
super.onLayoutChildren(recycler, state);
} catch (IndexOutOfBoundsException e) {
Log.e("Error", "IndexOutOfBoundsException in RecyclerView happens");
}
}
}
mRecyclerView.setLayoutManager(new WrapContentGridLayoutManager(getContext(), spanCount));
For me it works without any by-effect.
This issue is a known bug of RecyclerView. The best solution is, clear the list every time before refresh RecyclerView.
For fix this issue just call notifyDataSetChanged() with empty list before updating recycle view.
For example
//Method for refresh recycle view
if (!yourList.isEmpty())
yourList.clear(); //The list for update recycle view
adapter.notifyDataSetChanged();
Use this to refresh a RecyclerView
items.clear(); //here items is an ArrayList populating the RecyclerView
adapter.notifyDataSetChanged();
items.addAll(list);// add new data
adapter.notifyItemRangeInserted(0, items.size);// notify adapter of new data
`
I had similiar issue, and also this solution has helped me, after I've added new item to my RV:
recyclerView.getRecycledViewPool().clear();
adapter.notifyDataSetChanged();
Maybe you can try this before refresh the adapter:
dataList.clear();
patrolListAdapter.notifyDataSetChanged();
In my case I was doing it as notifyItemInserted(position);
That caused me this issue then i used as and it worked perfectly.notifyItemRangeInserted(startIndex,endIndex);
I had this problem when scrolling fast through my endless/paging RecyclerView. The root of my problem came from the fact that I had a “header” item at the beginning of the list, this header item was not a part of the data source, it was just inserted at the beginning of the adapter list. So when scrolling fast and adding new pages of items to the RecyclerView Adapter and notify the adapter that new data had been inserted, I was not taking into account the additional header item, thus making the size of the adapter’s list wrong... and causing this exception...
So in short, if you’re using a header/footer in our RecyclerView adapter make sure you take it into account when updating the adapters data.
Example:
public void addNewPageToList(List<MyData> list)
{ //
// Make sure you account for any header/footer in your list!
//
// Add one to the currentSize to account for the header item.
//
int currentSize = this.adapterList.size() + 1;
this.adapterList.addAll(list);
notifyItemRangeInserted(currentSize, this.adapterList.size());
}
Edit:
I guess you could always just use the adapter method getItemCount() to get the size, instead of getting the size from the “data list” and adding to it. Your getItemCount() method should already be taking into account any additional headers/footers/etc that you have in your list.
The problem is in this line of code:
mFeed = feeds;
you are assigning mFeed to the caller's instance feeds so whenever the caller changes it's variable (may be adding, clearing or removing items), your local mFeed will change
try to change to
mFeed.addAll(feeds);
don't forget to initialize mFeed to any list tat fits your needs like mFeed = new ArrayList<>();
put this line along with setting recyclerView. issue was fixed by setting ItemAnimator to null for RecyclerView.
in kotlin
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.itemAnimator = null
I'm using the recyclerview from mikepenz. And any update to the items using .set(item) was causing this issue.
For some reason, setting recylerView.itemAnimator = null, resolved the issue. This is a known android bug.
In my case, I was using RecyclerView from Firebase UI. Initially, the logic to initialize the RecyclerView was in onCreate(). To fix, I put the logic in onResume() and seems to be working for me. I had this error when going back to the Activity which had the RecyclerView. So, everytime the Activity screen is refreshed, the new data is loaded.
I had similar problem. Removing all views from RecyclerView helped me:
RecyclerView.LayoutManager layoutManager = mRecyclerView.getLayoutManager();
layoutManager.removeAllViews();
For me the issue was I wasn't posting notifyDatasetChanged when the data set changed as I implemented incremental search.
I had a list that was filtered based on what the user searched in the search widget. For each item in the list, I was making a remote request, and when I got the result back, I was updating that particular cell.
I had to do both notifies for the recycler view to work
Filter the original data set then post the dataset change
this.searchResultTable?.post {
this.searchResultTable?.adapter?.notifyDataSetChanged()
}
After receiving response, post notifications again
this.searchResultTable?.post {
this.searchResultTable?.adapter?.notifyItemChanged(index, updateDataHashMap)
}
You have to post updates rather than sending notifiy messages directly in order to prevent the recycler view from crashing when the update comes in before the view is laid out.
Another important gotcha is that when you post the individual updates after the remote response, you have to make sure that the list the user currently sees is the list that existed when the requests were sent.
For my case in adapter there was notifyItemRangeInserted and I replaced it with notifyItemRangeChanged