I have two RecyclerView inside the NestedScrollView and I need track viewed items of my RecyclerViews. But problem that using nestedScrollView the recycler pattern doesn’t work and all the views will be loaded at once because wrap_content needs the height of complete RecyclerView so it will draw all child Views at once.
Is there any way to track of the viewed items with this approach? Please help me.
never use RecyclerView inside NestedScrollView because your ViewHolders will not be recycled and you will be in danger of OutOfMemoeryExceptions, it may work for lists with small sizes but as the list size increases it becomes worse,
instead of using one ScrollView and 2 RecyclerView as child
you have to completely remove ScrollView and instead of that, use one RecyclerView with multitype ViewHolders, in other words you need to combine those 2 RecyclerView in on RecyclerView .
To achieving this you can combine those adapters manually or you can use ConcatAdapter that depends on what you want, this link may also help you if you want to use ConcatAdapter but that is not necessary.
then you can have different approaches to track the visibility of viewHolders like layoutManager.findFirstVisibleItemPosition() and etc.
Related
How can I implement this kind of UI, where we have two recyclerViews. One scrolls horizontally and the second one vertically. when the second one scrolls first one also scrolls top together.
I tried to implement using NestedScrollView, but I had to make second recyclerView height wrap content which causes recyclerView not recycle.
The second way that I tried was having one recyclerView. And adding horizontal recyclerview as a header. The problem was to save header recyclerview scroll state when navigation. And there had been crashes when loading next page (paging 3) in header recyclerView.
The question is: Is there any optimal solution for this kind of ui?
In cases, Like this, you don't have to use 2 RecyclerView and you also have to avoid using RecyclerView insideScrollView. instead of this you have to use one vertical RecyclerView with multitype view Adapter.
in this way, you are going to have 2 different ViewHolder one of them is a horizontal recyclerView (your top item) and the other one is your other items.
for learning multitype adapter you can see this:
How to create RecyclerView with multiple view types
and for a horizontal recyclerView inside a vertical RecyclerView you can see this :
https://medium.com/#ashishkudale/android-list-inside-list-using-recyclerview-73cff2c4ea95
you have to combine these 2.
I could not understand the meaning of "header" where you said "adding horizontal recyclerview as a header" but if you did what I told and the problem is the state of inner Horizontal recyclerView, I think probably you are calling setAdapter method of horizontal RecyclerView in OnBind() method of your vertical recycler view, it is a common mistake that I have seen in many tutorials.
if you have done this mistake , try to call setAdapter of your inner recyclerView in the constructor of its viewHolder and just update the list using yourHorizontalAdapter.notifyDataSetChanged() in onBind() method of VerticalRecylerView,
and if its not the case and your recyclerView is completely destroying see this link :How to save RecyclerView's scroll position using RecyclerView.State?
Default RecyclerView feature is to load only those items which are visible and load rest of the items as needed when user scrolls the list.
But my requirement is to load all items at once.
Any idea how to achieve this.
I am loading a Book and each page has multiple images for every line.
I am loading one image per item and I need to implement auto scroll feature for which I need to calculate whole recyclerview height.
I think instead of changing the default behavior of recyclerView if its possible use listView/gridView (until and unless you need StaggardGridView of recyclerView)
Just keep Recyclerview inside NestedScrollView. In simple first all the views regarding recyclerview items, that of cards is set to NestedScrollView and the things goes perfectly.
I created an activity with a ListView. That is a Friend ListView.
I wanna let it choose to add it to another View.
I don't know which View to choose is the best. Recyclerview or ScrollView?
Like this
Basic difference between RecyclerView and ListView are the below.
ListView is simple to implement. Default Adapters available.
But ViewHolder pattern and finding views using ID's used to give slow performance.
Now in RecyclerView , the above problems are attended using RecyclerView.ViewHolder.
For RecyclerView adapter, this ViewHolder is mandatory. While comparing to list view this is kinda complex, but solves performance issues in ListView.
Difference LayoutManagers are available while using RecyclerView.
LinearLayoutManager
StaggeredGridLayoutManager
GridLayoutManager
Major improvement of RecyclerView performance while comparing to ListView would be this according to developer.android.com
The RecyclerView creates only as many view holders as are needed to
display the on-screen portion of the dynamic content, plus a few
extra. As the user scrolls through the list, the RecyclerView takes
the off-screen views and rebinds them to the data which is scrolling
onto the screen
To sumup, RecyclerView is preferable than ListView (when UI is having same widgets repeating according to your data)
Now when to use ScrollView:
Your UI elements may not show completely in small device screens. But in bigger screen sizes it may!
Elements may not be necessarily only list / grid. It can have combinations of any UI widgets.
Eg:- TextViews vertically , with RadioButton and Button at last for user action.
This cannot be included in ListView/ RecyclerView , now you can add ScrollView which will have a LinearLayout/RelativeLayout . Inside which all other elements can be added.
Now you can
I recommend to user always RecyclerView and never a ListView. Use RecyclerView for element list and scrollview for static views.
Seeing your image Scrollview inside RecyclerView or ListView have problems with drag.
Use a vertical RecyclerView in all page and horizontal RecyclerView each row.
I suggest you to use RecyclerView because you will load lots of images and if you use ScrollView eventually you will use so much memory. Also it is recommended to use RecyclerView when you have dynamic data. You can look the definition of the RecyclerView in the Android Documentation as follow
RecyclerView is a view for efficiently displaying large data sets by
providing a limited window of data items.
You can use nested RecyclerView for creating such hierarchal view.
You can also checkout this example for nested RecyclerView usage.
Also you can further read:
Android Recyclerview vs ListView with Viewholder
RecyclerView vs. ListView
Should we use RecyclerView to replace ListView?
I hope this helps.
I have a ScrollView that contains several other views and I would like for one of these views to be a grid of other views having the same layout (e.g. ImageView).
Since having one scrollable view inside another is not recommended, I would like this grid view not to be scrollable, otherwise I would have used GridView or RecyclerView.
Surely I can place the grid views inside one of the standard layouts (e.g. TableLayout) but this may cause memory issues when many grid items exist.
Is there any standard approach or a library that allows to recycle views for a non scrollbale view inside ScrollView?
If you try to force GridView or RecyclerView to be non-scrollable (so basically you would have to force the dimensions of the view to display all the elements) you will end up in the same situation as if you used TableLayout (so you would need to watch out for memory issues).
If you disable the scrolling of scrollable (recycling) elements like GridView/RecyclerView you disable the most important part that makes those things work efficiently (that makes those things reuse their views).
The way you should solve your issue is to implement your other Views of your ScrollView as a part of the RecyclerView. Your RecyclerView should be equipped with the adapter that can inflate multiple types of Views (you can read about it for example here).
Since you are using RecyclerView you could use NestedScrollView instead of ScrollView They should play more nicely since RecyclerView extends from NestedScrollingChild and NestedScrollView extends from NestedScrollingParent.
Other views you can use are VerticalGridView or HorizontalGridView but as you said you are worried about performance issues and you can provide a GridLayoutManager to the RecyclerView I would stick with that.
My assignment is to create an interface much same like Google Play Store.There will a Category name followed by 3 or 4 cards (horizontal) followed by More button. Then again next category.
I already had implemented this using nesting the horizontal listview inside Vertical listview.
I know, I can achieve this by using the Recycler view with LinearLayoutManager with horizontal orientation. Using this I'll be having one only row.
My question is how do I add 2nd, 3rd row to this?
Should I use again nested Recycler view?
Are there some better options?
Dont use nested listviews (you cant scroll horizontally in play store).
Consider the following options:
You can use a simple LinearLayoutManager and make different view types. For the with 3 cards horizontally use a GridLayout or LinearLayout with same weights. The problem here is, that you have to consider the indexes of your underlying data list used in the adapter
Write your own LayoutManager for RecyclerView
Use TwoWay View which is based on RecyclerView and offers a Spannable Grid Layout manager, which seems to be what you are looking for.
If you inspect the layout of the Google Play app, they do not use a listview/recyclerview for the horizontal cards. I'm pretty sure that is just a linearlayout (horizontal) within a vertical listview / recyclerview.
If you insist on using a horizontal recyclerview for each row, then having a nested recyclerview would be your best option. You can specify a RecycledViewPool so that all the nested recyclerviews share the same pool instead of creating their own.
You may like to do it as one vertical RecyclerView (Main recycler) and for every section you can inflate a horizontal RecyclerView as well (Section recycler) as this blog answer mention:
Also, consider using:
A cache layer for Bitmaps for persistent access through your other store screens
A lazy load method for your category/section images
A place holder before showing new items