Android: Scrollview VS Nestedscrollview

Android: ScrollView vs NestedScrollView

NestedScrollView as the name suggests is used when there is a need for a scrolling view inside another scrolling view. Normally this would be difficult to accomplish since the system would be unable to decide which view to scroll.

This is where NestedScrollView comes in.

What is the difference b/t Default Android Scrolling functionality VS ScrollView / Nested Scrollview?

A ScrollView is like a little window you can scroll up and down so you can see all its content - it can be any size on the screen. Like @Marrows says, by default nothing scrolls - if a widget is off the screen, it's off the screen!

So if your layout requires stuff that might not all fit - say because there's a variable amount of it, or things can expand (like a large text field), or because on smaller screens (or in landscape) there's potentially not enough room - you need to explicitly allow for some or all of your UI to scroll by putting it in a scroll view.

One typical way to do this is to have fixed items at the top and bottom of the screen, and put a scrollview in the rest of the space. That way, if there's room to display all its contents at once, great! Otherwise if it gets squished, the user can still scroll its display and access everything.

The layout inside the ScrollView needs to be big enough to hold all its content (usually wrap content) otherwise stuff will get cut off as usual. The scroll view itself defines how big the window into that layout is. That larger layout just moves up and down behind it.

A RecyclerView is a type of ScrollingView which is why you might have thought it was typical behaviour (and TextViews allow you to scroll inside them too, if they're smaller than their contents)

NestedScrollView scrolls on top when content changes

This is happening because the recyclerView's container is set to wrap_content , so when the height get smaller than the NestedScrollView, it gets scrolled to top.

you can fix it by providing a height larger than NestedScrollView :

So add minHeight :

<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/nested_scrollView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:descendantFocusability="blocksDescendants"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:orientation="vertical">
        <TextView
            android:id="@+id/description_tv"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="36dp"
            android:text="Very long random text..." />
        <Button
            android:id="@+id/filter_1_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Filter 1" />
        <Button
            android:id="@+id/filter_2_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Filter 2" />
        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="1000dp">
           <!-- Add min height to support scrolling-->
            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/list"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="24dp" />
        </FrameLayout>
    </LinearLayout>
</androidx.core.widget.NestedScrollView>

NestedScrollView/ ScrollView is not scrolling when some layout are included to the child of ScrollView

So, this is the dumbest mistake that took my whole day to figure out.

The first child of my constraint layout is constrained to bottom of tv1 which is not even present in the whole layout. (Copy pasting mistake)

    <TextView
            android:id="@+id/tv2"
            style="@style/RegularBlack"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/_8sdp"
            android:text="My support will include assistance with :"
            android:textAlignment="viewStart"
            app:layout_constraintTop_toBottomOf="@+id/tv1" />

changed it to

 app:layout_constraintTop_toTopOf="parent" 

and the scroll started working. :)

NestedScrollView inside a ScrollView is not scrolling for API17

Try changing it into this format and see if it works:

<NestetScrollView>

    <Other Views/>
    <Other Views/>

    <ScrollView>

        <CustomTextView/>

   </ScrollView>

</NestetScrollView>

NestedScrollView requestRectangleOnScreen not scrolling view to center

view.top returns the top position of a view relative to its direct parent, in your case it's the top position in relation to a greater parent is required for that you can use a method like the following to aggregate the top position of a view in relation to the scrollView and scroll to it

private fun ScrollView.scrollTo(target: View) {
        var topPosition = 0
        var view = target
        while (view !== this) {
            topPosition += view.top
            view = view.parent as View
        }
        smoothScrollTo(0, topPosition)
    }

so to scroll to any view you just call scrollView.scrollTo(view)

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