I'm using basic RecyclerView with GridLayoutManager. I observed that nor smoothScrollToPosition nor scrollToPosition works properly.
a) when using smoothScrollToPosition I often receive error from RecyclerView
"RecyclerView﹕ Passed over target position while smooth scrolling."
and RecyclerView is not scrolled properly (often it misses the targeted row). This is observed mostly when I'm trying to scroll to the 1st item of some row
b) when using scrollToPosition it seems to work quite ok but most of the time I can see only the 1st item of the row and the rest are not displayed.
Can you give me some hints how to make work properly at least one of the methods?
Thanks a lot!
Finally I was able to make it work! LinearLayoutManager.scrollToPositionWithOffset(int, int) did the trick.
I also have same issue, but managed to fix the issue by Customizing SmoothScroller
let Custom LayoutManager as below
public class CustomLayoutManager extends LinearLayoutManager {
private static final float MILLISECONDS_PER_INCH = 50f;
private Context mContext;
public CustomLayoutManager(Context context) {
super(context);
mContext = context;
}
@Override
public void smoothScrollToPosition(RecyclerView recyclerView,
RecyclerView.State state, final int position) {
LinearSmoothScroller smoothScroller =
new LinearSmoothScroller(mContext) {
//This controls the direction in which smoothScroll looks
//for your view
@Override
public PointF computeScrollVectorForPosition
(int targetPosition) {
return CustomLayoutManager.this
.computeScrollVectorForPosition(targetPosition);
}
//This returns the milliseconds it takes to
//scroll one pixel.
@Override
protected float calculateSpeedPerPixel
(DisplayMetrics displayMetrics) {
return MILLISECONDS_PER_INCH/displayMetrics.densityDpi;
}
};
smoothScroller.setTargetPosition(position);
startSmoothScroll(smoothScroller);
}
}
(documentation commented inside the code given above)Please set the above LayoutManager to the recyerview
CustomLayoutManagerlayoutManager = new CustomLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.smoothScrollToPosition(position);
by using the custom Layout manager
scrollToPosition also working well in my case u can use
recyclerView.scrollToPosition(position)
also if you want to adjust the speed of smoothScrollToPosition please override the
private static final float MILLISECONDS_PER_INCH = 50f;
in CustomLayoutManager. So if we put the value as 1f the smoothScrollToPosition will be faster like scrollToPosition.increasing value make delay and decreasing will make the speed of scroll. Hope this will useful.
In My case,
`mRecyclerView.scrollToPosition(10);`
also did not work. But
`mRecyclerView.smoothScrollToPosition(10);`
works fine for me...
To scroll down to bottom from any position in the RecyclerView on clicking EditText.
edittext.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
rv_commentList.postDelayed(new Runnable() {
@Override
public void run() {
rv_commentList.scrollToPosition(rv_commentList.getAdapter().getItemCount() - 1);
}
}, 1000);
}
});
Try measuring item width or height and call smoothScrollBy(int dx, int dy).
recyclerView.getLayoutManager().smoothScrollToPosition(recyclerView,new RecyclerView.State(),currentPosition);
How to perform smooth scrolling and save RecyclerView vertical position after device rotating:
This is the method that works for my case,
public class MainFragment extends Fragment { //OR activity it's //fragment in my case
....
@Override
public void onLoadFinished(@NonNull Loader<List<Report>> loader, List<Report> objects) { // or other method of your choice, in my case it's a Loader
RecyclerView recyclerViewRv = findViewById(........;
.....
recyclerViewRv.setAdapter(.....Your adapter);
recyclerViewRv.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);
recyclerScrollY = recyclerViewRv. computeVerticalScrollOffset();
}
});
//Apply smooth vertical scroll
recyclerViewRv.smoothScrollBy(0,recyclerScrollY);
}
//Save vertical scroll position before rotating devices
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("recyclerScrollY",recyclerScrollY);
}
//BackUp vertical scroll position after rotating devices
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null) {
recyclerScrollY = savedInstanceState.getInt("recyclerScrollY");
}
}
//If you want to perform the same operation for horizontal scrolling just add a variable called recyclerScrollX = recyclerScrollY = recyclerViewRv. computeHorizontalScrollOffset(); then save in bundle
Calling the recyclerView smoothScroll isn't effective, as the recyclerView itself doesn't handle its layout.
What you should do is calling the layout manager scroll method instead.
This should look something like this
mRecyclerView.getLayoutManager().scrollToPosition(desiredPosition);
If you are trying to do a quick scroll to a position at the top of the RecyclerView, just use LinearLayoutManager.scrollToPositionWithOffset with 0 as the offset.
Example:
mLinearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(mLinearLayoutManager);
mLinearLayoutManager.scrollToPositionWithOffset(myPosition, 0);
smoothScrollToPosition is very slow. If you want something fast go with scrollToPositionWithOffset.
when you use scrollToPosition it will show it on top of the recycler view.
But if you use smoothScrollToPosition it will scroll till it come in to Window Visible. that's why while smoothScrool to item below, it will show it on bottom
来源：https://stackoverflow.com/questions/30845742/smoothscrolltoposition-doesnt-work-properly-with-recyclerview