Get visible items in RecyclerView
AndroidAndroid RecyclerviewAndroid Problem Overview
I need to know which elements are currently displayed in my RecyclerView. There is no equivalent to the OnScrollListener.onScroll(...)
method on ListViews. I tried to work with View.getGlobalVisibleRect(...)
, but that hack is too ugly and does not always work too.
Someone any ideas?
Android Solutions
Solution 1 - Android
First / last visible child depends on the LayoutManager
.
If you are using LinearLayoutManager
or GridLayoutManager
, you can use
int findFirstVisibleItemPosition();
int findFirstCompletelyVisibleItemPosition();
int findLastVisibleItemPosition();
int findLastCompletelyVisibleItemPosition();
For example:
GridLayoutManager layoutManager = ((GridLayoutManager)mRecyclerView.getLayoutManager());
int firstVisiblePosition = layoutManager.findFirstVisibleItemPosition();
For LinearLayoutManager
, first/last depends on the adapter ordering. Don't query children from RecyclerView
; LayoutManager
may prefer to layout more items than visible for caching.
Solution 2 - Android
for those who have a logic to be implemented inside the RecyclerView adapter you can still use @ernesto approach combined with an on scrollListener to get what you want
as the RecyclerView is consulted.
Inside the adapter you will have something like this:
@Override
public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
if(manager instanceof LinearLayoutManager && getItemCount() > 0) {
LinearLayoutManager llm = (LinearLayoutManager) manager;
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int visiblePosition = llm.findFirstCompletelyVisibleItemPosition();
if(visiblePosition > -1) {
View v = llm.findViewByPosition(visiblePosition);
//do something
v.setBackgroundColor(Color.parseColor("#777777"));
}
}
});
}
}
Solution 3 - Android
Finally, I found a solution to know if the current item is visible, from the onBindViewHolder event in the adapter.
The key is the method isViewPartiallyVisible from LayoutManager.
In your adapter, you can get the LayoutManager from the RecyclerView, which you get as parameter from the onAttachedToRecyclerView event.
Solution 4 - Android
You can use recyclerView.getChildAt()
to get each visible child, and setting some tag convertview.setTag(index)
on these view in adapter code will help you to relate it with adapter data.
Solution 5 - Android
Addendum:
The proposed functions findLast...Position() do not work correctly in a scenario with a collapsing toolbar while the toolbar is expanded.
It seems that the recycler view has a fixed height, and while the toolbar is expanded, the recycler is moved down, partially out of the screen. As a consequence, the results of the proposed functions are too high. Example: The last visible item is told to be #9, but in fact item #7 is the last one that is on screen.
This behavior is also the reason why my view often failed to scroll to the correct position, i.e. scrollToPosition() did not work correctly (I finally collapsed the toolbar programmatically).
Solution 6 - Android
Following Linear / Grid LayoutManager
methods can be used to check which items are visible
int findFirstVisibleItemPosition();
int findLastVisibleItemPosition();
int findFirstCompletelyVisibleItemPosition();
int findLastCompletelyVisibleItemPosition();
and if you want to track is item visible on screen
for some threshold then you can refer to the following blog.
https://proandroiddev.com/detecting-list-items-perceived-by-user-8f164dfb1d05
Solution 7 - Android
Every answer above is correct and I would like to add also a snapshot from my working codes.
recycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
// Some code when initially scrollState changes
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
// Some code while the list is scrolling
LinearLayoutManager lManager = (LinearLayoutManager) recyclerView.getLayoutManager();
int firstElementPosition = lManager.findFirstVisibleItemPosition();
}
});
Solution 8 - Android
For StaggeredGridLayoutManager
do this:
RecyclerView rv = findViewById(...);
StaggeredGridLayoutManager lm = new StaggeredGridLayoutManager(...);
rv.setLayoutManager(lm);
And to get visible item views:
int[] viewsIds = lm.findFirstCompletelyVisibleItemPositions(null);
ViewHolder firstViewHolder = rvPlantios.findViewHolderForLayoutPosition(viewsIds[0]);
View itemView = viewHolder.itemView;
Remember to check if it is empty.
Solution 9 - Android
You can find the first and last visible children of the recycle view and check if the view you're looking for is in the range:
var visibleChild: View = rv.getChildAt(0)
val firstChild: Int = rv.getChildAdapterPosition(visibleChild)
visibleChild = rv.getChildAt(rv.childCount - 1)
val lastChild: Int = rv.getChildAdapterPosition(visibleChild)
println("first visible child is: $firstChild")
println("last visible child is: $lastChild")
Solution 10 - Android
For those who are looking for an answer in Kotlin -
fun getVisibleItem(recyclerView : RecyclerView) {
recyclerView.addOnScrollListener(object: RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
if(newState == RecyclerView.SCROLL_STATE_IDLE) {
val index = (recyclerView.layoutManager.findFirstVisibleItemPosition
//use this index for any operation you want to perform on the item visible on screen. eg. log(arrayList[index])
}
}
})
}
You can explore other methods for getting position as per your use case.
int findFirstCompletelyVisibleItemPosition()
int findLastVisibleItemPosition()
int findLastCompletelyVisibleItemPosition()
Solution 11 - Android
I hope below code helps someone define int a
above methods. if visibile item position different before item position toast message will show on screen
myRecyclerview.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
LinearLayoutManager manager= (LinearLayoutManager) myRecyclerview.getLayoutManager();
assert manager != null;
int visiblePosition = manager.findLastCompletelyVisibleItemPosition();
if(visiblePosition > -1&&a!=visiblePosition) {
Toast.makeText(context,String.valueOf(visiblePosition),Toast.LENGTH_SHORT).show();
//do something
a=visiblePosition;
}
}
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
//Some code while the list is scrolling
}
});