Develop Reference

How to keep the last item's focus of RecyclerView when navigating to the end of the list?

I used a RecyclerView with HORIZONTAL direction in my TV development which controlled by a D-pad to navigate the list from the left to right. the last item of the RecyclerView always lost focus when navigating to the right-most of the list.
So how can i keep the last item's focus when navigating to the end of the list?

I dug into the source code of RecyclerView, i found the onInterceptFocusSearch method in the LayoutManager, inner class of RecyclerView.
/**
* This method gives a LayoutManager an opportunity to intercept the initial focus search
* before the default behavior of {#link FocusFinder} is used. If this method returns
* null FocusFinder will attempt to find a focusable child view. If it fails
* then {#link #onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State)}
* will be called to give the LayoutManager an opportunity to add new views for items
* that did not have attached views representing them. The LayoutManager should not add
* or remove views from this method.
*
* #param focused The currently focused view
* #param direction One of { #link View#FOCUS_UP}, {#link View#FOCUS_DOWN},
* {#link View#FOCUS_LEFT}, {#link View#FOCUS_RIGHT},
* {#link View#FOCUS_BACKWARD}, {#link View#FOCUS_FORWARD}
* #return A descendant view to focus or null to fall back to default behavior.
* The default implementation returns null.
*/
public View onInterceptFocusSearch(View focused, int direction) {
return null ;
}
which gives a LayoutManager an opportunity to intercept the initial focus search before the default behavior of FocusFinder is used.
So i overrided the onInterceptFocusSearch likes below, and used the CustomGridLayoutManager for my RecylerView, which works like a charming.
public class CustomGridLayoutManager extends android.support.v7.widget.GridLayoutManager {
public CustomGridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr,
int defStyleRes) {
super (context, attrs, defStyleAttr, defStyleRes);
}
public CustomGridLayoutManager(Context context, int spanCount) {
super (context, spanCount);
}
public CustomGridLayoutManager(Context context, int spanCount, int orientation,
boolean reverseLayout) {
super (context, spanCount, orientation, reverseLayout);
}
#Override
public View onInterceptFocusSearch(View focused, int direction) {
int pos = getPosition(focused);
int count = getItemCount();
int orientation = getOrientation();
**********
do some logic
what i did was return the focused View when the focused view is the last item of RecyclerView.
**********
return super .onInterceptFocusSearch(focused, direction);
}
}

If you're using a subclass of BaseGridView, like HorizontalGridView or VerticalGridView, set an onKeyInterceptListener that swallows the movement key at the end of the list. For example, with a HorizontalGridView:
grid.setOnKeyInterceptListener { event ->
val focused = grid.focusedChild
event?.keyCode == KEYCODE_DPAD_RIGHT && grid.layoutManager.getPosition(focused) == grid.adapter.itemCount-1
}
If you're using RecyclerView directly, then use onInterceptFocusSearch with a custom LinearLayoutManager. For example, with a LinearLayoutManager.VERTICAL list:
list.layoutManager = object: LinearLayoutManager(context, LinearLayoutManager.VERTICAL, false) {
override fun onInterceptFocusSearch(focused: View?, direction: Int): View? {
if (direction == View.FOCUS_DOWN) {
val pos = getPosition(focused)
if (pos == itemCount-1)
return focused
}
if (direction == View.FOCUS_UP) {
val pos = getPosition(focused)
if (pos == 0)
return focused
}
return super.onInterceptFocusSearch(focused, direction)
}
}

inspired bythis issues ,there is another workaround:
in RecyclerView.Adapter<ViewHolder>
int focusPos;
#Override
public void onBindViewHolder(ComposeViewHolder holder,
final int position) {
....
if (focusPos == position) { // focus last clicked view again
holder.imageView.requestFocus();
}
....
holder.imageView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
....
focusPos = position;
notifyDataSetChanged();
}
});
}

I'm adding an answer for Kotlin.
If in each place you will override the base layout, then your code can get a lot more complicated, especially since when working with TV you will want to add something behavior to layout manager.
I checked this on Xiaomi TV stick and X62 Max with D-PAD, also with emulators, it works.
So I suggest creating a class like this:
class TvLinearLayoutManager(
context: Context?,
orientation: Int,
reverseLayout: Boolean) : LinearLayoutManager(context, orientation, reverseLayout) {
override fun onInterceptFocusSearch(focused: View, direction: Int): View? {
return if (
// This prevent focus jumping near border items
(getPosition(focused)==itemCount-1 && direction == View.FOCUS_RIGHT) ||
(getPosition(focused)==0 && direction == View.FOCUS_LEFT)
)
focused
else
super.onInterceptFocusSearch(focused, direction)
}}

Controlling touch event propagation in case of overlapping views

I have some problem trying to control touch event propagation within my RecycleView. So I have a RecyclerView populating a set of CardViews imitating a card stack (so they overlap each other with a certain displacement, though they have different elevation value). My current problem is that each card has a button and since relative card displacement is smaller than height of the button it results in the situation that buttons are overlapping and whenever a touch event is dispatched it starts propagating from the bottom of view hierarchy (from children with highest child number).
According to articles I read (this, this and also this video) touch propagation is dependent on the order of views in parent view, so touch will first be delivered to the child with highest index, while I want the touch event to be processed only by touchables of the topmost view and RecyclerView (it also has to process drag and fling gestures). Currently I am using a fallback with cards that are aware of their position within parent's view hierarchy to prevent wrong children from processing touches but this is really ugly way to do that. My assumption is that I have to override dispatchTouchEvent method of the RecyclerView and properly dispatch a touch event only to topmost child. However, when I tried this way of doing that (which is also kind of clumsy):
#Override
public boolean dispatchTouchEvent(MotionEvent ev) {
View topChild = getChildAt(0);
for (View touchable : topChild.getTouchables()) {
int[] location = new int[2];
touchable.getLocationOnScreen(location);
RectF touchableRect = new RectF(location[0],
location[1],
location[0] + touchable.getWidth(),
location[1] + touchable.getHeight());
if (touchableRect.contains(ev.getRawX(), ev.getRawY())) {
return touchable.dispatchTouchEvent(ev);
}
}
return onTouchEvent(ev);
}
Only DOWN event was delivered to the button within a card (no click event triggered). I will appreciate any advice on the way of reversing touch event propagation order or on delegating of touch event to a specific View. Thank you very much in advance.
EDIT: This is the screenshot of how the example card stack is looking like
Example adapter code:
public class TestAdapter extends RecyclerView.Adapter {
List<Integer> items;
public TestAdapter(List<Integer> items) {
this.items = items;
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.test_layout, parent, false);
return new TestHolder(v);
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
TestHolder currentHolder = (TestHolder) holder;
currentHolder.number.setText(Integer.toString(position));
currentHolder.tv.setTag(position);
currentHolder.tv.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int pos = (int) v.getTag();
Toast.makeText(v.getContext(), Integer.toString(pos) + "clicked", Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return items.size();
}
private class TestHolder extends RecyclerView.ViewHolder {
private TextView tv;
private TextView number;
public TestHolder(View itemView) {
super(itemView);
tv = (TextView) itemView.findViewById(R.id.click);
number = (TextView) itemView.findViewById(R.id.number);
}
}
}
and an example card layout:
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_margin="16dp"
android:textSize="24sp"
android:id="#+id/number"/>
<TextView android:layout_width="wrap_content"
android:layout_height="64dp"
android:gravity="center"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_margin="16dp"
android:textSize="24sp"
android:text="CLICK ME"
android:id="#+id/click"/>
</RelativeLayout>
</android.support.v7.widget.CardView>
And here is the code that I am using now to solve the problem (this approach I do not like, I want to find better way)
public class PositionAwareCardView extends CardView {
private int mChildPosition;
public PositionAwareCardView(Context context) {
super(context);
}
public PositionAwareCardView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PositionAwareCardView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public void setChildPosition(int pos) {
mChildPosition = pos;
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// if it's not the topmost view in view hierarchy then block touch events
return mChildPosition != 0 || super.onInterceptTouchEvent(ev);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
return false;
}
}
EDIT 2: I've forgotten to mention, this problem is present only on pre-Lolipop devices, it seems that starting from Lolipop, ViewGroups also take elevation into consideration while dispatching touch events
EDIT 3: Here is my current child drawing order:
#Override
protected int getChildDrawingOrder(int childCount, int i) {
return childCount - i - 1;
}
EDIT 4: Finally I was able to fix the problem thanks to user random, and this answer, the solution was extremely simple:
#Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (!onInterceptTouchEvent(ev)) {
if (getChildCount() > 0) {
final float offsetX = -getChildAt(0).getLeft();
final float offsetY = -getChildAt(0).getTop();
ev.offsetLocation(offsetX, offsetY);
if (getChildAt(0).dispatchTouchEvent(ev)) {
// if touch event is consumed by the child - then just record it's coordinates
x = ev.getRawX();
y = ev.getRawY();
return true;
}
ev.offsetLocation(-offsetX, -offsetY);
}
}
return super.dispatchTouchEvent(ev);
}

CardView uses elevation API on L and before L, it changes the shadow size. dispatchTouchEvent in L respects Z ordering when iterating over children which doesn't happen in pre L.
Looking at the source code:
Pre Lollipop
ViewGroup#dispatchTouchEvent
public boolean dispatchTouchEvent(MotionEvent ev) {
final boolean customOrder = isChildrenDrawingOrderEnabled();
for (int i = childrenCount - 1; i >= 0; i--) {
final int childIndex = customOrder ?
getChildDrawingOrder(childrenCount, i) : i;
final View child = children[childIndex];
...
Lollipop
ViewGroup#dispatchTouchEvent
public boolean dispatchTouchEvent(MotionEvent ev) {
// Check whether any clickable siblings cover the child
// view and if so keep track of the intersections. Also
// respect Z ordering when iterating over children.
ArrayList<View> orderedList = buildOrderedChildList();
final boolean useCustomOrder = orderedList == null
&& isChildrenDrawingOrderEnabled();
final int childCount = mChildrenCount;
for (int i = childCount - 1; i >= 0; i--) {
final int childIndex = useCustomOrder
? getChildDrawingOrder(childCount, i) : i;
final View sibling = (orderedList == null)
? mChildren[childIndex] : orderedList.get(childIndex);
// We care only about siblings over the child
if (sibling == child) {
break;
}
...
The child drawing order can be overridden with custom child drawing order in a ViewGroup, and with setZ(float) custom Z values set on Views.
You might want to check custom child drawing order in a ViewGroup but I think your current fix for the problem is good enough.

Did you try to set your topmost view as clickable ?
button.setClickable(true);
If this attribute is not set (as default) in the View XML it propagate the click event upwards.
But if you set it on the topmost view as true, it shouldn't propagate any event on any other view.

Scroll RecyclerView to show selected item on top

I'm looking for a way to scroll a RecyclerView to show the selected item on top.
In a ListView I was able to do that by using scrollTo(x,y) and getting the top of the element that need to be centered.
Something like:
#Override
public void onItemClick(View v, int pos){
mylistView.scrollTo(0, v.getTop());
}
The problem is that the RecyclerView returns an error when using it's scrollTo method saying
RecyclerView does not support scrolling to an absolute position
How can I scroll a RecyclerView to put the selected item at the top of the view?

If you are using the LinearLayoutManager or Staggered GridLayoutManager, they each have a scrollToPositionWithOffset method that takes both the position and also the offset of the start of the item from the start of the RecyclerView, which seems like it would accomplish what you need (setting the offset to 0 should align with the top).
For instance:
//Scroll item 2 to 20 pixels from the top
linearLayoutManager.scrollToPositionWithOffset(2, 20);

If you looking for vertical LinearLayout Manager you can achieve smooth scrolling using a custom LinearSmoothScroller:
import android.content.Context;
import android.graphics.PointF;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.LinearSmoothScroller;
import android.support.v7.widget.RecyclerView;
public class SnappingLinearLayoutManager extends LinearLayoutManager {
public SnappingLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
#Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
int position) {
RecyclerView.SmoothScroller smoothScroller = new TopSnappedSmoothScroller(recyclerView.getContext());
smoothScroller.setTargetPosition(position);
startSmoothScroll(smoothScroller);
}
private class TopSnappedSmoothScroller extends LinearSmoothScroller {
public TopSnappedSmoothScroller(Context context) {
super(context);
}
#Override
public PointF computeScrollVectorForPosition(int targetPosition) {
return SnappingLinearLayoutManager.this
.computeScrollVectorForPosition(targetPosition);
}
#Override
protected int getVerticalSnapPreference() {
return SNAP_TO_START;
}
}
}
use an instance of the layoutmanager in recycle view and then calling recyclerView.smoothScrollToPosition(pos); will smooth scroll to selected position to top of the recycler view

//Scroll item pos
linearLayoutManager.scrollToPositionWithOffset(pos, 0);

You just need to call recyclerview.scrollToPosition(position). That's fine!
If you want to call it in adapter, just let your adapter has the instance of recyclerview or the activity or fragment which contains recyclerview,than implements the method getRecyclerview() in them.
I hope it can help you.

If you want to scroll automatic without show scroll motion then you need to write following code:
mRecyclerView.getLayoutManager().scrollToPosition(position);
If you want to display scroll motion then you need to add following code.
=>Step 1: You need to declare SmoothScroller.
RecyclerView.SmoothScroller smoothScroller = new
LinearSmoothScroller(this.getApplicationContext()) {
#Override
protected int getVerticalSnapPreference() {
return LinearSmoothScroller.SNAP_TO_START;
}
};
=>step 2: You need to add this code any event you want to perform scroll to specific position.
=>First you need to set target position to SmoothScroller.
smoothScroller.setTargetPosition(position);
=>Then you need to set SmoothScroller to LayoutManager.
mRecyclerView.getLayoutManager().startSmoothScroll(smoothScroller);

just call this method simply:
((LinearLayoutManager)recyclerView.getLayoutManager()).scrollToPositionWithOffset(yourItemPosition,0);
instead of:
recyclerView.scrollToPosition(yourItemPosition);

same with speed regulator
public class SmoothScrollLinearLayoutManager extends LinearLayoutManager {
private static final float MILLISECONDS_PER_INCH = 110f;
private Context mContext;
public SmoothScrollLinearLayoutManager(Context context,int orientation, boolean reverseLayout) {
super(context,orientation,reverseLayout);
mContext = context;
}
#Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
int position) {
RecyclerView.SmoothScroller smoothScroller = new TopSnappedSmoothScroller(recyclerView.getContext()){
//This controls the direction in which smoothScroll looks for your view
#Override
public PointF computeScrollVectorForPosition(int targetPosition) {
return new PointF(0, 1);
}
//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);
}
private class TopSnappedSmoothScroller extends LinearSmoothScroller {
public TopSnappedSmoothScroller(Context context) {
super(context);
}
#Override
public PointF computeScrollVectorForPosition(int targetPosition) {
return SmoothScrollLinearLayoutManager.this
.computeScrollVectorForPosition(targetPosition);
}
#Override
protected int getVerticalSnapPreference() {
return SNAP_TO_START;
}
}
}

Try what worked for me cool!
Create a variable private static int displayedposition = 0;
Now for the position of your RecyclerView in your Activity.
myRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager llm = (LinearLayoutManager) myRecyclerView.getLayoutManager();
displayedposition = llm.findFirstVisibleItemPosition();
}
});
Place this statement where you want it to place the former site displayed in your view .
LinearLayoutManager llm = (LinearLayoutManager) mRecyclerView.getLayoutManager();
llm.scrollToPositionWithOffset(displayedposition , youList.size());
Well that's it , it worked fine for me \o/

what i did to restore the scroll position after refreshing the RecyclerView on button clicked:
if (linearLayoutManager != null) {
index = linearLayoutManager.findFirstVisibleItemPosition();
View v = linearLayoutManager.getChildAt(0);
top = (v == null) ? 0 : (v.getTop() - linearLayoutManager.getPaddingTop());
Log.d("TAG", "visible position " + " " + index);
}
else{
index = 0;
}
linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.scrollToPositionWithOffset(index, top);
getting the offset of the first visible item from the top before creating the linearLayoutManager object and after instantiating it the scrollToPositionWithOffset of the LinearLayoutManager object was called.

I don't know why I didn't find the best answer but its really simple.
recyclerView.smoothScrollToPosition(position);
No errors
Creates Animations

What i may add here is how to make it work together with DiffUtil and ListAdapter
You may note that calling recyclerView.scrollToPosition(pos) or (recyclerView.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(pos, offset) wouldn't work if called straight after adapter.submitList. It is because the differ looks for changes in a background thread and then asynchronously notifies adapter about changes. On a SO i have seen several wrong answers with unnecessary delays & etc to solve this.
To handle the situation properly the submitList has a callback which is invoked when changes have been applied.
So the proper kotlin implementations in this case are:
//memorise target item here and a scroll offset if needed
adapter.submitList(items) {
val pos = /* here you may find a new position of the item or just use just a static position. It depends on your case */
recyclerView.scrollToPosition(pos)
}
//or
adapter.submitList(items) { recyclerView.smoothScrollToPosition(pos) }
//or etc
adapter.submitList(items) { (recyclerView.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(pos, offset) }

Introduction
None of the answers explain how to show last item(s) at the top. So, the answers work only for items that still have enough items above or below them to fill the remaining RecyclerView. For instance, if there are 59 elements and a 56-th element is selected it should be at the top as in the picture below:
So, let's see how to implement this in the next paragraph.
Solution
We could handle those cases by using linearLayoutManager.scrollToPositionWithOffset(pos, 0) and additional logic in the Adapter of RecyclerView - by adding a custom margin below the last item (if the last item is not visible then it means there's enough space fill the RecyclerView). The custom margin could be a difference between the root view height and the item height. So, your Adapter for RecyclerView would look as follows:
...
#Override
public void onBindViewHolder(ViewHolder holder, final int position) {
...
int bottomHeight = 0;
int itemHeight = holder.itemView.getMeasuredHeight();
// if it's the last item then add a bottom margin that is enough to bring it to the top
if (position == mDataSet.length - 1) {
bottomHeight = Math.max(0, mRootView.getMeasuredHeight() - itemHeight);
}
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams)holder.itemView.getLayoutParams();
params.setMargins(0, 0, params.rightMargin, bottomHeight);
holder.itemView.setLayoutParams(params);
...
}
...

If your LayoutManager is LinearLayoutManager you can use scrollToPositionWithOffset(position,0); on it and it will make your item the first visible item in the list. Otherwise, you can use smoothScrollToPosition on the RecyclerView directly.
I ended up using the below code.
RecyclerView.LayoutManager layoutManager = mainList.getLayoutManager();
if (layoutManager instanceof LinearLayoutManager) {
// Scroll to item and make it the first visible item of the list.
((LinearLayoutManager) layoutManager).scrollToPositionWithOffset(position, 0);
} else {
mainList.smoothScrollToPosition(position);
}

scroll at particular position
and this helped me alot.
by click listener you can get the position in your adapter
layoutmanager.scrollToPosition(int position);

In my case my RecyclerView have a padding top like this
<android.support.v7.widget.RecyclerView
...
android:paddingTop="100dp"
android:clipToPadding="false"
/>
Then for scroll a item to top, I need to
recyclerViewLinearLayoutManager.scrollToPositionWithOffset(position, -yourRecyclerView.getPaddingTop());

please note that if scrollToPosition not work notice that your RecyclerView was inside a NestedScrollView; refer to this post

This is pretty simple
recyclerView.scrollToPosition(position)

If you've Recycler view inside nestedscrollview :
val y = recyclerview.getChildAt(0).y
recyclerview.smoothScrollTo(0, y.toInt())
If your Recycler view is not inside nestedscrollview :
recyclerview.smoothScrollToPosition(index)
or
recyclerview.layoutManager?.smoothScrollToPosition(recyclerview, null ,index)

I use the code below to smooth-scroll an item (thisView) to the top.
It works also for GridLayoutManager with views of different heights:
View firstView = mRecyclerView.getChildAt(0);
int toY = firstView.getTop();
int firstPosition = mRecyclerView.getChildAdapterPosition(firstView);
View thisView = mRecyclerView.getChildAt(thisPosition - firstPosition);
int fromY = thisView.getTop();
mRecyclerView.smoothScrollBy(0, fromY - toY);
Seems to work good enough for a quick solution.

How to manually smoothScrollTo() a fragment view on a ViewPager

I'm working on a Circular ViewPager, and i've implemented this exactly solution (https://stackoverflow.com/a/12965787/1083564).
The only thing is missing, is the fact that i need to smoothScroll when i'm using the setCurrentItem(int i, bol b) method, that instantly goes to the pixel limit, without using the smoothScroll.
I already have the access to use this method, using the following code:
package android.support.v4.view;
import android.content.Context;
import android.util.AttributeSet;
public class MyViewPager extends ViewPager {
public MyViewPager(Context context) {
super(context);
}
public MyViewPager(Context context, AttributeSet attr) {
super(context, attr);
}
public void smoothScrollTo(int x, int y, int velocity) {
super.smoothScrollTo(x, y, velocity);
}
}
But i couldn't figure it out where and how to use it. I have the number of pixels that i need to run smoothly by using this code inside the setOnPageChangeListener on my ViewPager:
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
Log.d( "viewpager", positionOffsetPixels+"");
}
Before it goes to 0, instantly, because of the setCurrentItem, i have the value of pixels left to reach 0 (to the left) or x (to the right, depending of screen). I dont know how can i get this x number too.
PS: I think this solution is the exatcly one used by IMDB app. You can see this scrolling from the first to the last but one, without remove your finger (use 2 fingers to do it). You will see that the "white limit" will show from the left side of the ViewPager. The only difference is that they know how to smooth scroll after using the setCurrentItem.
If you need some more information, please, ask! Thanks!

Issue: When you detect circular scrolling has to be perfomed, calling setCurrentItem immediately will cause the ViewPager to scroll to the real fragment immediately without smooth scrolling as it is set to false.
Solution: Instead allow the ViewPager to scroll to the fake fragment smoothly as it does for other fragments and then scroll to the real fragment after some delay with smooth scrolling set to false. User will not notice the change.
When we are performing circular scrolling, call setCurrentItem in a runnable with some delay. Use onPageSelected to know the index of the page selected.
public void onPageSelected(int position) {
// Consider eg. : C' A B C A'
boolean circularScroll = false;
if(position == 0) {
// Position 0 is C', we need to scroll to real C which is at index 3.
position = mPager.getAdapter().getCount() - 2;
circularScroll = true;
}
int lastIndex = mPager.getAdapter().getCount() - 1;
if(position == lastIndex) {
// Last index is A', we need to scroll to real A, which is at index 1.
position = 1;
circularScroll = true;
}
if(circularScroll) {
final int realPosition = position;
mPager.postDelayed(new Runnable() {
#Override
public void run() {
mPager.setCurrentItem(realPosition, false);
}
}, 500L);
}
}

When you set the second parameter of the setCurrentItem to true it should smooth scroll
#Override
public void onPageScrollStateChanged (int state) {
if (state == ViewPager.SCROLL_STATE_IDLE) {
int curr = viewPager.getCurrentItem();
int lastReal = viewPager.getAdapter().getCount() - 2;
if (curr == 0) {
viewPager.setCurrentItem(lastReal, true);
} else if (curr > lastReal) {
viewPager.setCurrentItem(1, true);
}
}
}

Is there a way to programmatically scroll a scroll view to a specific edit text?

I have a very long activity with a scrollview. It is a form with various fields that the user must fill in. I have a checkbox half way down my form, and when the user checks it I want to scroll to a specific part of the view. Is there any way to scroll to an EditText object (or any other view object) programmatically?
Also, I know this is possible using X and Y coords but I want to avoid doing this as the form may changed from user to user.

private final void focusOnView(){
yourScrollView.post(new Runnable() {
#Override
public void run() {
yourScrollView.scrollTo(0, yourEditText.getBottom());
}
});
}

The answer of Sherif elKhatib can be greatly improved, if you want to scroll the view to the center of the scroll view. This reusable method smooth scrolls the view to the visible center of a HorizontalScrollView.
private final void focusOnView(final HorizontalScrollView scroll, final View view) {
new Handler().post(new Runnable() {
#Override
public void run() {
int vLeft = view.getLeft();
int vRight = view.getRight();
int sWidth = scroll.getWidth();
scroll.smoothScrollTo(((vLeft + vRight - sWidth) / 2), 0);
}
});
}
For a vertical ScrollView use
...
int vTop = view.getTop();
int vBottom = view.getBottom();
int sHeight = scroll.getBottom();
scroll.smoothScrollTo(0, ((vTop + vBottom - sHeight) / 2));
...

This works well for me :
targetView.getParent().requestChildFocus(targetView,targetView);
public void RequestChildFocus (View child, View focused)
child - The child of this ViewParent that wants focus. This view will contain the focused view. It is not necessarily the view that actually has focus.
focused - The view that is a descendant of child that actually has focus

In my opinion the best way to scroll to a given rectangle is via View.requestRectangleOnScreen(Rect, Boolean). You should call it on a View you want to scroll to and pass a local rectangle you want to be visible on the screen. The second parameter should be false for smooth scrolling and true for immediate scrolling.
final Rect rect = new Rect(0, 0, view.getWidth(), view.getHeight());
view.requestRectangleOnScreen(rect, false);

I made a small utility method based on Answer from WarrenFaith, this code also takes in account if that view is already visible in the scrollview, no need for scroll.
public static void scrollToView(final ScrollView scrollView, final View view) {
// View needs a focus
view.requestFocus();
// Determine if scroll needs to happen
final Rect scrollBounds = new Rect();
scrollView.getHitRect(scrollBounds);
if (!view.getLocalVisibleRect(scrollBounds)) {
new Handler().post(new Runnable() {
#Override
public void run() {
scrollView.smoothScrollTo(0, view.getBottom());
}
});
}
}

You should make your TextView request focus:
mTextView.requestFocus();

Another varition would be:
scrollView.postDelayed(new Runnable()
{
#Override
public void run()
{
scrollView.smoothScrollTo(0, img_transparent.getTop());
}
}, 200);
or you can use the post() method.

My EditText was nested several layers inside my ScrollView, which itself isn't the layout's root view. Because getTop() and getBottom() were seeming to report the coordinates within it's containing view, I had it compute the distance from the top of the ScrollView to the top of the EditText by iterating through the parents of the EditText.
// Scroll the view so that the touched editText is near the top of the scroll view
new Thread(new Runnable()
{
#Override
public
void run ()
{
// Make it feel like a two step process
Utils.sleep(333);
// Determine where to set the scroll-to to by measuring the distance from the top of the scroll view
// to the control to focus on by summing the "top" position of each view in the hierarchy.
int yDistanceToControlsView = 0;
View parentView = (View) m_editTextControl.getParent();
while (true)
{
if (parentView.equals(scrollView))
{
break;
}
yDistanceToControlsView += parentView.getTop();
parentView = (View) parentView.getParent();
}
// Compute the final position value for the top and bottom of the control in the scroll view.
final int topInScrollView = yDistanceToControlsView + m_editTextControl.getTop();
final int bottomInScrollView = yDistanceToControlsView + m_editTextControl.getBottom();
// Post the scroll action to happen on the scrollView with the UI thread.
scrollView.post(new Runnable()
{
#Override
public void run()
{
int height =m_editTextControl.getHeight();
scrollView.smoothScrollTo(0, ((topInScrollView + bottomInScrollView) / 2) - height);
m_editTextControl.requestFocus();
}
});
}
}).start();

The above answers will work fine if the ScrollView is the direct parent of the ChildView. If your ChildView is being wrapped in another ViewGroup in the ScrollView, it will cause unexpected behavior because the View.getTop() get the position relative to its parent. In such case, you need to implement this:
public static void scrollToInvalidInputView(ScrollView scrollView, View view) {
int vTop = view.getTop();
while (!(view.getParent() instanceof ScrollView)) {
view = (View) view.getParent();
vTop += view.getTop();
}
final int scrollPosition = vTop;
new Handler().post(() -> scrollView.smoothScrollTo(0, scrollPosition));
}

I know this may be too late for a better answer but a desired perfect solution must be a system like positioner. I mean, when system makes a positioning for an Editor field it places the field just up to the keyboard, so as UI/UX rules it is perfect.
What below code makes is the Android way positioning smoothly. First of all we keep the current scroll point as a reference point. Second thing is to find the best positioning scroll point for an editor, to do this we scroll to top, and then request the editor fields to make the ScrollView component to do the best positioning. Gatcha! We've learned the best position. Now, what we'll do is scroll smoothly from the previous point to the point we've found newly. If you want you may omit smooth scrolling by using scrollTo instead of smoothScrollTo only.
NOTE: The main container ScrollView is a member field named scrollViewSignup, because my example was a signup screen, as you may figure out a lot.
view.setOnFocusChangeListener(new View.OnFocusChangeListener() {
#Override
public void onFocusChange(final View view, boolean b) {
if (b) {
scrollViewSignup.post(new Runnable() {
#Override
public void run() {
int scrollY = scrollViewSignup.getScrollY();
scrollViewSignup.scrollTo(0, 0);
final Rect rect = new Rect(0, 0, view.getWidth(), view.getHeight());
view.requestRectangleOnScreen(rect, true);
int new_scrollY = scrollViewSignup.getScrollY();
scrollViewSignup.scrollTo(0, scrollY);
scrollViewSignup.smoothScrollTo(0, new_scrollY);
}
});
}
}
});
If you want to use this block for all EditText instances, and quickly integrate it with your screen code. You can simply make a traverser like below. To do this, I've made the main OnFocusChangeListener a member field named focusChangeListenerToScrollEditor, and call it during onCreate as below.
traverseEditTextChildren(scrollViewSignup, focusChangeListenerToScrollEditor);
And the method implementation is as below.
private void traverseEditTextChildren(ViewGroup viewGroup, View.OnFocusChangeListener focusChangeListenerToScrollEditor) {
int childCount = viewGroup.getChildCount();
for (int i = 0; i < childCount; i++) {
View view = viewGroup.getChildAt(i);
if (view instanceof EditText)
{
((EditText) view).setOnFocusChangeListener(focusChangeListenerToScrollEditor);
}
else if (view instanceof ViewGroup)
{
traverseEditTextChildren((ViewGroup) view, focusChangeListenerToScrollEditor);
}
}
}
So, what we've done here is making all EditText instance children to call the listener at focus.
To reach this solution, I've checked it out all the solutions here, and generated a new solution for better UI/UX result.
Many thanks to all other answers inspiring me much.

yourScrollView.smoothScrollTo(0, yourEditText.getTop());
Just Do It ;)

scrollView.post(new Runnable() {
#Override
public void run() {
scrollView.smoothScrollTo(0, myTextView.getTop());
}
});
Answering from my practical project.

I think I have found more elegant and less error prone solution using
ScrollView.requestChildRectangleOnScreen
There is no math involved, and contrary to other proposed solutions, it will handle correctly scrolling both up and down.
/**
* Will scroll the {#code scrollView} to make {#code viewToScroll} visible
*
* #param scrollView parent of {#code scrollableContent}
* #param scrollableContent a child of {#code scrollView} whitch holds the scrollable content (fills the viewport).
* #param viewToScroll a child of {#code scrollableContent} to whitch will scroll the the {#code scrollView}
*/
void scrollToView(ScrollView scrollView, ViewGroup scrollableContent, View viewToScroll) {
Rect viewToScrollRect = new Rect(); //coordinates to scroll to
viewToScroll.getHitRect(viewToScrollRect); //fills viewToScrollRect with coordinates of viewToScroll relative to its parent (LinearLayout)
scrollView.requestChildRectangleOnScreen(scrollableContent, viewToScrollRect, false); //ScrollView will make sure, the given viewToScrollRect is visible
}
It is a good idea to wrap it into postDelayed to make it more reliable, in case the ScrollView is being changed at the moment
/**
* Will scroll the {#code scrollView} to make {#code viewToScroll} visible
*
* #param scrollView parent of {#code scrollableContent}
* #param scrollableContent a child of {#code scrollView} whitch holds the scrollable content (fills the viewport).
* #param viewToScroll a child of {#code scrollableContent} to whitch will scroll the the {#code scrollView}
*/
private void scrollToView(final ScrollView scrollView, final ViewGroup scrollableContent, final View viewToScroll) {
long delay = 100; //delay to let finish with possible modifications to ScrollView
scrollView.postDelayed(new Runnable() {
public void run() {
Rect viewToScrollRect = new Rect(); //coordinates to scroll to
viewToScroll.getHitRect(viewToScrollRect); //fills viewToScrollRect with coordinates of viewToScroll relative to its parent (LinearLayout)
scrollView.requestChildRectangleOnScreen(scrollableContent, viewToScrollRect, false); //ScrollView will make sure, the given viewToScrollRect is visible
}
}, delay);
}

reference : https://stackoverflow.com/a/6438240/2624806
Following worked far better.
mObservableScrollView.post(new Runnable() {
public void run() {
mObservableScrollView.fullScroll([View_FOCUS][1]);
}
});

Examining Android source code, you can find that there already is a member function of ScrollView– scrollToChild(View) – that does exactly what is requested. Unfortunatelly, this function is for some obscure reason marked private. Based on that function I've written following function that finds the first ScrollView above the View specified as a parameter and scrolls it so that it becomes visible within the ScrollView:
private void make_visible(View view)
{
int vt = view.getTop();
int vb = view.getBottom();
View v = view;
for(;;)
{
ViewParent vp = v.getParent();
if(vp == null || !(vp instanceof ViewGroup))
break;
ViewGroup parent = (ViewGroup)vp;
if(parent instanceof ScrollView)
{
ScrollView sv = (ScrollView)parent;
// Code based on ScrollView.computeScrollDeltaToGetChildRectOnScreen(Rect rect) (Android v5.1.1):
int height = sv.getHeight();
int screenTop = sv.getScrollY();
int screenBottom = screenTop + height;
int fadingEdge = sv.getVerticalFadingEdgeLength();
// leave room for top fading edge as long as rect isn't at very top
if(vt > 0)
screenTop += fadingEdge;
// leave room for bottom fading edge as long as rect isn't at very bottom
if(vb < sv.getChildAt(0).getHeight())
screenBottom -= fadingEdge;
int scrollYDelta = 0;
if(vb > screenBottom && vt > screenTop)
{
// need to move down to get it in view: move down just enough so
// that the entire rectangle is in view (or at least the first
// screen size chunk).
if(vb-vt > height) // just enough to get screen size chunk on
scrollYDelta += (vt - screenTop);
else // get entire rect at bottom of screen
scrollYDelta += (vb - screenBottom);
// make sure we aren't scrolling beyond the end of our content
int bottom = sv.getChildAt(0).getBottom();
int distanceToBottom = bottom - screenBottom;
scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
}
else if(vt < screenTop && vb < screenBottom)
{
// need to move up to get it in view: move up just enough so that
// entire rectangle is in view (or at least the first screen
// size chunk of it).
if(vb-vt > height) // screen size chunk
scrollYDelta -= (screenBottom - vb);
else // entire rect at top
scrollYDelta -= (screenTop - vt);
// make sure we aren't scrolling any further than the top our content
scrollYDelta = Math.max(scrollYDelta, -sv.getScrollY());
}
sv.smoothScrollBy(0, scrollYDelta);
break;
}
// Transform coordinates to parent:
int dy = parent.getTop()-parent.getScrollY();
vt += dy;
vb += dy;
v = parent;
}
}

My solution is:
int[] spinnerLocation = {0,0};
spinner.getLocationOnScreen(spinnerLocation);
int[] scrollLocation = {0, 0};
scrollView.getLocationInWindow(scrollLocation);
int y = scrollView.getScrollY();
scrollView.smoothScrollTo(0, y + spinnerLocation[1] - scrollLocation[1]);

Vertical scroll, good for forms. Answer is based on Ahmadalibaloch horizontal scroll.
private final void focusOnView(final HorizontalScrollView scroll, final View view) {
new Handler().post(new Runnable() {
#Override
public void run() {
int top = view.getTop();
int bottom = view.getBottom();
int sHeight = scroll.getHeight();
scroll.smoothScrollTo(0, ((top + bottom - sHeight) / 2));
}
});
}

You can use ObjectAnimator like this:
ObjectAnimator.ofInt(yourScrollView, "scrollY", yourView.getTop()).setDuration(1500).start();

Add postDelayed to the view so that getTop() does not return 0.
binding.scrollViewLogin.postDelayed({
val scrollTo = binding.textInputLayoutFirstName.top
binding.scrollViewLogin.isSmoothScrollingEnabled = true
binding.scrollViewLogin.smoothScrollTo(0, scrollTo)
}, 400
)
Also make sure the view is a direct child of scrollView, otherwise you would get getTop() as zero. Example: getTop() of edittext which is embedded inside TextInputLayout would return 0. So in this case, we have to compute getTop() of TextInputLayout which is a direct child of ScrollView.
<ScrollView>
<TextInputLayout>
<EditText/>
</TextInputLayout>
</ScrollView>

In my case, that's not EditText, that's googleMap.
And it works successfully like this.
private final void focusCenterOnView(final ScrollView scroll, final View view) {
new Handler().post(new Runnable() {
#Override
public void run() {
int centreX=(int) (view.getX() + view.getWidth() / 2);
int centreY= (int) (view.getY() + view.getHeight() / 2);
scrollView.smoothScrollBy(centreX, centreY);
}
});
}

Que:Is there a way to programmatically scroll a scroll view to a specific edittext?
Ans:Nested scroll view in recyclerview last position added record data.
adapter.notifyDataSetChanged();
nested_scroll.setScrollY(more Detail Recycler.getBottom());
Is there a way to programmatically scroll a scroll view to a specific edit text?

The following is what I'm using:
int amountToScroll = viewToShow.getBottom() - scrollView.getHeight() + ((LinearLayout.LayoutParams) viewToShow.getLayoutParams()).bottomMargin;
// Check to see if scrolling is necessary to show the view
if (amountToScroll > 0){
scrollView.smoothScrollTo(0, amountToScroll);
}
This gets the scroll amount necessary to show the bottom of the view, including any margin on the bottom of that view.

Based on Sherif's answer, the following worked best for my use case. Notable changes are getTop() instead of getBottom() and smoothScrollTo() instead of scrollTo().
private void scrollToView(final View view){
final ScrollView scrollView = findViewById(R.id.bookmarksScrollView);
if(scrollView == null) return;
scrollView.post(new Runnable() {
#Override
public void run() {
scrollView.smoothScrollTo(0, view.getTop());
}
});
}

If you want to scroll to a view when a soft keyboard is opened, then it might get a bit tricky.
The best solution I've got so far is to use a combination of inset callbacks and requestRectangleOnScreen method.
First, you need to setup inset callbacks:
fun View.doOnApplyWindowInsetsInRoot(block: (View, WindowInsetsCompat, Rect) -> Unit) {
val initialPadding = recordInitialPaddingForView(this)
val root = getRootForView(this)
ViewCompat.setOnApplyWindowInsetsListener(root) { v, insets ->
block(v, insets, initialPadding)
insets
}
requestApplyInsetsWhenAttached()
}
fun View.requestApplyInsetsWhenAttached() {
if (isAttachedToWindow) {
requestApplyInsets()
} else {
addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {
override fun onViewAttachedToWindow(v: View) {
v.removeOnAttachStateChangeListener(this)
v.requestApplyInsets()
}
override fun onViewDetachedFromWindow(v: View) = Unit
})
}
}
We are setting a callback on a root view to make sure we get called. Insets could be consumed before our view in question received them, so we have to do additional work here.
Now it's almost easy:
doOnApplyWindowInsetsInRoot { _, _, _ ->
post {
if (viewInQuestion.hasFocus()) {
requestRectangleOnScreen(Rect(0, 0, width, height))
}
}
}
You can get rid of a focus check. It's there to limit number of calls to requestRectangleOnScreen. I use post to run an action after scrollable parent scheduled scroll to a focused view.

If anybody is looking for a Kotlin version you can do this with an extension function
fun ScrollView.scrollToChild(view: View, onScrolled: (() -> Unit)? = null) {
view.requestFocus()
val scrollBounds = Rect()
getHitRect(scrollBounds)
if (!view.getLocalVisibleRect(scrollBounds)) {
findViewTreeLifecycleOwner()?.lifecycleScope?.launch(Dispatchers.Main) {
smoothScrollTo(0, view.bottom - 40)
onScrolled?.invoke()
}
}
}
There is a little callback that lets you do something after the scroll.

If scrlMain is your NestedScrollView, then use the following:
scrlMain.post(new Runnable() {
#Override
public void run() {
scrlMain.fullScroll(View.FOCUS_UP);
}
});

here is another better version for efficient scrolling:
kotlin code to scroll to particular position of view added in scrollview(horizontal)
horizontalScrollView.post {
val targetView = findViewById<View>(R.id.target_view)
val targetX = targetView.left
horizontalScrollView.smoothScrollTo(targetX, 0)
}
for vertical scroll just change targetView.left to targetView.top
for JAVA here is a sample code:
scrollView.postDelayed(new Runnable() {
#Override
public void run() {
int targetViewY = targetView.getTop();
scrollView.smoothScrollTo(0, targetViewY);
}
}, 500);