How do I make RecyclerView update its layout? - android

I have a RecyclerView with a bunch of custom views which may change height after a while, because they contain ImageViews which load their image asynchronously. The RecyclerView does not pick up on this layout change, although I call forceLayout on the ImageView, and the RecyclerView is initialized with setHasFixedSize(false). All container-parents of the ImageView have set android:layout_height="wrap_content".
How can I make the RecyclerView update its layout? With good'ol ListView this was not a problem.

You can use the notifyDataSetChanged in the Adapter for the RecyclerView if all your images change at the same time or notifyItemChanged(int position) if only one of the items has changed. This will tell the RecyclerView to rebind the particular View.

Google has finally fixed this in support library v23.2. Issue is fixed by updating this line in build.gradle after updating your support repository with the SDK Manager:
compile 'com.android.support:recyclerview-v7:23.2.0'

Call the notifyDataSetChanged() or notifyItemChanged(int position) methods of the RecyclerView.Adapter from the MAIN THREAD. Calling it from an AsyncTask may result in the main thread not updating the ImageViews. Its most convenient to have a callback method in the activity/fragment work as a listener, and have it called by the AsyncTask in onPostExecute()

int wantedPosition = 25; // Whatever position you're looking for
int firstPosition = linearLayoutManager.findFirstVisibleItemPosition(); // This is the same as child #0
int wantedChild = wantedPosition - firstPosition;
if (wantedChild < 0 || wantedChild >= linearLayoutManager.getChildCount()) {
Log.w(TAG, "Unable to get view for desired position, because it's not being displayed on screen.");
return;
}
View wantedView = linearLayoutManager.getChildAt(wantedChild);
mlayoutOver =(LinearLayout)wantedView.findViewById(R.id.layout_over);
mlayoutPopup = (LinearLayout)wantedView.findViewById(R.id.layout_popup);
mlayoutOver.setVisibility(View.INVISIBLE);
mlayoutPopup.setVisibility(View.VISIBLE);
This code is worked for me.

I had the same problem, I just set a fix width and height for the ImageView. Try that and see where you get. You can also use a lib for this, I use Square Picasso and I got it working with RecyclerView.

Related

View not hiding when dynamically done in recycler view item

I am using RecyclerView to list Items and In each single list displaying an image which will be Visible/Gone dynamically. I am using View.GONE to hide the view.
In a condition where the image should hide is not working always. It is still showing in screen,and also in debug mode i have checked that and when getting the
image.getVisiblity() it is giving me int value "8" which means the view is Gone,But still i can see that image in that list.
It happens only sometimes.
And i tried to use View.INVISIBLE and it is working all the time but it is taking the space in layout which is as expected
I am using sparseArray to store all the holders classes.I have written a method in Adapter and calling this from activity.I am trying to hide the replayIcon view
public void handleReplayButton(int pos,Boolean isDisplay) {
Holder holder = holderSparseArray.get(pos);
if(holder != null) {
if (isDisplay != null && isDisplay == true) {
holder.playIcon.setVisibility(View.GONE);
holder.pauseIcon.setVisibility(View.GONE);
holder.replayIcon.setVisibility(View.VISIBLE);
} else if(isDisplay != null && isDisplay == false) {
holder.playIcon.setVisibility(View.VISIBLE);
holder.pauseIcon.setVisibility(View.GONE);
holder.replayIcon.setVisibility(View.GONE);
} else {
holder.playIcon.setVisibility(View.GONE);
holder.pauseIcon.setVisibility(View.VISIBLE);
holder.replayIcon.setVisibility(View.GONE);
}
}
}
Here it is going to the last else statement what i want and it is setting the view to GONE.and when i call holder.replayIcon.getVisibility() it is giving me int 8 but,still i can see the icon
Try calling invisible at the end of one statement which makes it visible and vice versa.
Or
You can also try to put notifydatasetchanged().
You will have to call notifyDataSetChanged() to refresh the list in the recycler view.
But since you have to remove an item, you can also use notifyItemRemoved
Also, if you are using setVisibility() method to HIDE the view, then make sure you also set the view as VISIBLE for valid items, because the items are reused in a recycler view.
For more : https://developer.android.com/reference/android/support/v7/widget/RecyclerView.Adapter
If you will call notifyDataSetChanged() - it will update all the items in the list.
Don't do that if you need to update special items by index because it will take a lot of memory to redraw the all views.
Instead like the guys wrote before you should use notifyItemChanged(), notifyItemInserted() or notifyItemRemoved().
If you want to update couple views use can use notifyItemRangeChanged(), notifyItemRangeRemoved() or notifyItemRangeInserted().
You can read more about it here
Also there is one way to it. You can use DiffUtils callbacks.
Pretty good approach that work with animation already.
DiffUtils Calbacks

How to make specified item not update when notifyDataSetChanged in RecyclerView

I have a item in RecyclerView which does not need to be updated when I call notifyDataSetChanged.
But I didn't find any methods to make the specified item avoid updated. Is it possible to do this ?
I need to do this because the item is a WebView, it had loaded a html page, if I called notifyDataSetChanged, this item will flash.
The reason why I post this question is avoiding the flash of the WebView when notifyDataSetChanged (see this quesion). After the failure of using notifyItemRangeXXX methods, I post this question.
But after checking your answers and comments, it seems that it's impossible to avoid updating when using notifyDataSetChanged.
Yes, its actually possible to do so. notifyDataSetChanged() notifies the RecyclerView that all the elements in the data set has changed.
As you do not want that to happen and exclude specific items.
for(int i = 0; i< mAdapter.getItemCount(); i++){
if(i != itemPositionToExclude){
mAdapter.notifyItemChanged(i);
}
}
So, we need to loop through all the elements in the adapter and call notifyItemChanged() only for those positions which you do not want to exclude.
The purpose of notifyDataSetChanged IS to update ALL items. Don't use it if you don't want this behavior!
The correct approach would be to only update the data you've changed. There are some methods which will help you to only invalidate the desired data:
notifyItemChanged(int position)
notifyItemInserted(int position)
notifyItemMoved(int fromPosition, int toPosition)
notifyItemRangeChanged(int positionStart, int itemCount)
notifyItemRangeRemoved(int positionStart, int itemCount)
notifyItemRemoved(int position)
You should think in different way - which items need to be updated. To update UI of item, after data has changed use method notifyitemchanged

How to use RecyclerView.Adapter notifyItemInserted/Removed in a right way?

For instance, you have an adapter and in onBindViewHolder method you set OnClickListener to some views (and do some actions there depending on view position). You should assign final to position param of method onBindViewHolder so it could be accessible from onClick().
After changing dataset (remove or add item in list) you call onItemInserted or onItemRemoved and this really adds/removes a view in the recyclerview, BUT it does not refresh other viewitems so when you click on a neighbor viewitem it will open a screen or show data with invalid index. To avoid this I basically call notifyDatasetChanged to call onBind to all visible views and remove/add some views.
So how to refresh other views when you call notifyItemInserted/removed or how to work with these methots appropriately?
Assigning the position to a variable in onBindViewHolder will lead to an inconsistent state if items in the dataset are inserted or deleted without calling notifyDataSetChanged.
To use onItemInserted or onItemRemoved the data in the viewholder should remain consistent since it will not be redrawn and onClick would use this invalid position assigned before an item was added or removed.
For this and other use cases the RecyclerView.ViewHolder provides methods to access its position and id:
Use getAdapterPosition() or getItemId() to get valid positions and ids.
Also have a look on the other methods available in RecyclerView.ViewHolder.
So, the way I fix the problem I had is by changing the position into viewHolder.getAdapterPosition()
Cheers!
I advise you to add notifyItemRangeChanged after insert or remove list inside adapter. This work for my project.
Example in remove item :
public void removeItem (int pos) {
simpanList.remove(pos);
notifyItemRemoved(pos);
notifyItemRangeChanged(pos, simpanList.size());//add here, this can refresh position cmiiw
}
For future readers, this is what I do when inserting/removing in recyclerview
For example, my model class is CarsModel
In my adapter
ArrayList<CarsModel> carsModel;
In onBindViewHolder
CardModel model = carsModel.get(position);
When removing data in list using button in holder:
int position = holder.getAdapterPosition();
carsModel.remove(position);
notifyItemRemoved(position);
Then when inserting
carsModel.add(0, model);
notifyItemInserted(0);
or insert in last row
carsModel.add(carsModel.size() - 1 , model);
notifyItemInserted(carsModel.size()-1);

Android Robolectric Click RecyclerView Item

Is there any way to simulate a click on a RecyclerView item with Robolectric?
So far, I have tried getting the View at the first visible position of the RecyclerView, but that is always null. It's getChildCount() keeps returning 0, and findViewHolderForPosition is always null. The adapter returns a non-0 number from getItemCount() (there are definitely items in the adapter).
I'm using Robolectric 2.4 SNAPSHOT.
Seems like the issue was that RecyclerView needs to be measured and layed out manually in Robolectric. Calling this solves the problem:
recyclerView.measure(0, 0);
recyclerView.layout(0, 0, 100, 10000);
With Robolectric 3 you can use visible():
ActivityController<MyActivity> activityController = Robolectric.buildActivity(MyActivityclass);
activityController.create().start().visible();
ShadowActivity myActivityShadow = shadowOf(activityController.get());
RecyclerView currentRecyclerView = ((RecyclerView) myActivityShadow.findViewById(R.id.myrecyclerid));
currentRecyclerView.getChildAt(0).performClick();
This eliminates the need to trigger the measurement of the view by hand.
Expanding on Marco Hertwig's answer:
You need to add the recyclerView to an activity so that its layout methods are called as expected. You could call them manually, (like in Elizer's answer) but you would have to manage the state yourself. Also, this would not be simulating an actual use-case.
Code:
#Before
public void setup() {
ActivityController<Activity> activityController =
Robolectric.buildActivity(Activity.class); // setup a default Activity
Activity activity = activityController.get();
/*
Setup the recyclerView (create it, add the adapter, add a LayoutManager, etc.)
...
*/
// set the recyclerView object as the only view in the activity
activity.setContentView(recyclerView);
// start the activity
activityController.create().start().visible();
}
Now you don't need to worry about calling layout and measure everytime your recyclerView is updated (by adding/removing items from the adapter, for example).
Just invoke
Robolectric.flushForegroundThreadScheduler()
before performClick() to ensure that all ui operations (including measure and layout phases of recycler view after populating with the dataset) are finished

Is there a way to prevent the listview from scrolling to its top position when its adapter's data is changed?

I'm having a bit of trouble preserving the scroll position of a list view when changing it's adapter's data.
What I'm currently doing is to create a custom ArrayAdapter (with an overridden getView method) in the onCreate of a ListFragment, and then assign it to its list:
mListAdapter = new CustomListAdapter(getActivity());
mListAdapter.setNotifyOnChange(false);
setListAdapter(mListAdapter);
Then, when I receive new data from a loader that fetches everything periodically, I do this in its onLoadFinished callback:
mListAdapter.clear();
mListAdapter.addAll(data.items);
mListAdapter.notifyDataSetChanged();
The problem is, calling clear() resets the listview's scroll position. Removing that call preserves the position, but it obviously leaves the old items in the list.
What is the proper way to do this?
As you pointed out yourself, the call to 'clear()' causes the position to be reset to the top.
Fiddling with scroll-position, etc. is a bit of a hack to get this working.
If your CustomListAdapter subclasses from ArrayAdapter, this could be the issue:
The call to clear(), calls 'notifyDataSetChanged()'. You can prevent this:
mListAdapter.setNotifyOnChange(false); // Prevents 'clear()' from clearing/resetting the listview
mListAdapter.clear();
mListAdapter.addAll(data.items);
// note that a call to notifyDataSetChanged() implicitly sets the setNotifyOnChange back to 'true'!
// That's why the call 'setNotifyOnChange(false) should be called first every time (see call before 'clear()').
mListAdapter.notifyDataSetChanged();
I haven't tried this myself, but try it :)
Check out: Maintain/Save/Restore scroll position when returning to a ListView
Use this to save the position in the ListView before you call .clear(), .addAll(), and . notifyDataSetChanged().
int index = mList.getFirstVisiblePosition();
View v = mList.getChildAt(0);
int top = (v == null) ? 0 : v.getTop();
After updating the ListView adapter, the Listview's items will be changed and then set the new position:
mList.setSelectionFromTop(index, top);
Basically you can save you position and scroll back to it, save the ListView state or the entire application state.
Other helpful links:
Save Position:
How to save and restore ListView position in Android
Save State:
Android ListView y position
Regards,
Please let me know if this helps!
There is one more use-case I came across recently (Android 8.1) - caused by bug in Android code. If I use mouse-wheel to scroll list view - consecutive adapter.notifyDataSetChanged() resets scroll position to zero. Use this workaround until bug gets fixed in Android
listView.onTouchModeChanged(true); // workaround
adapter.notifyDataSetChanged();
More details is here: https://issuetracker.google.com/u/1/issues/130103876
In your Expandable/List Adapter, put this method
public void refresh(List<MyDataClass> dataList) {
mDataList.clear();
mDataList.addAll(events);
notifyDataSetChanged();
}
And from your activity, where you want to update the list, put this code
if (mDataListView.getAdapter() == null) {
MyDataAdapter myDataAdapter = new MyDataAdapter(mContext, dataList);
mDataListView.setAdapter(myDataAdapter);
} else {
((MyDataAdapter)mDataListView.getAdapter()).refresh(dataList);
}
In case of Expandable List View, you will use
mDataListView.getExpandableListAdapter() instead of
mDataListView.getAdapter()

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