Nestedscrollview's Smoothscrollto() Behaves Weird

What I am trying to achieve is to scroll to scroll_position_1 when tab1 (and so on) is clicked like this. I don't understand what's happening at all. Below is the structure of my l

Solution 1:

Looks like there is a bug when programmatically scrolling NestedScrollView within CoordinatorLayout. This solved my problem:

privatevoidscrollToView(final View view){
    mScroller.scrollBy(0, 1);
    mScroller.smoothScrollTo(0, view.getTop());
}

or for better control:

private void scrollToView(final View view) {
    mScroller.scrollBy(0, 1);
    ObjectAnimator.ofInt(mScroller, "scrollY",  view.getTop()).setDuration(700).start();
}

Solution 2:

You can use a ListView instead of a ConstraintLayout and add the text views to the list. Then, you can simply call listView.smoothScrollToPosition(index) instead of worrying about the x and y coordinates.

1) Edit your layout as shown below.

2) Add items to your ListView via code.

3) Upon tab click, call listView.smoothScrollToPosition(index_of_text_view) and your list view scrolls to that position.

<?xml version="1.0" encoding="utf-8"?><android.support.design.widget.CoordinatorLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"><android.support.v4.widget.NestedScrollViewandroid:layout_width="match_parent"android:layout_height="match_parent"app:layout_behavior="@string/appbar_scrolling_view_behavior"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical"app:layout_behavior="@string/appbar_scrolling_view_behavior"><android.support.design.widget.TabLayoutandroid:id="@+id/sliding_tabs"android:layout_width="match_parent"android:layout_height="wrap_content"android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"/><android.support.design.widget.TabLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"><android.support.design.widget.TabItemandroid:layout_height="wrap_content"android:layout_width="wrap_content"/><android.support.design.widget.TabItemandroid:layout_height="wrap_content"android:layout_width="wrap_content"/></android.support.design.widget.TabLayout><ListViewandroid:id="@+id/list_view"android:layout_width="match_parent"android:layout_height="wrap_content"/>
       </LinearLayout
</android.support.v4.widget.NestedScrollView><android.support.design.widget.AppBarLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"><android.support.design.widget.CollapsingToolbarLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"app:layout_scrollFlags="scroll|snap"><ImageViewandroid:layout_width="match_parent"android:layout_height="180dp"android:scaleType="centerCrop"app:layout_collapseMode="parallax"/><android.support.v7.widget.Toolbarandroid:layout_width="match_parent"android:layout_height="?attr/actionBarSize"app:layout_collapseMode="pin"app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/></android.support.design.widget.CollapsingToolbarLayout></android.support.design.widget.AppBarLayout>

Solution 3:

When tab is clicked, just get the desired view's y position relative to the root view and scroll to that position.

publicclassMainActivityextendsAppCompatActivity {

  private NestedScrollView nestedScrollView;
  private CoordinatorLayout coordinatorLayout;
  TextView textView;


  @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    nestedScrollView = findViewById(R.id.nsv);
    coordinatorLayout = findViewById(R.id.cl);
    textView = findViewById(R.id.scroll_position_1);

    TabLayouttabLayout= findViewById(R.id.tl);
    tabLayout.addOnTabSelectedListener(newTabLayout.BaseOnTabSelectedListener() {
      @OverridepublicvoidonTabSelected(TabLayout.Tab tab) {
        if(tab.getPosition() == 1/*position of your desired tab*/){
          scrollToView(textView);
        }
      }

      @OverridepublicvoidonTabUnselected(TabLayout.Tab tab) {

      }

      @OverridepublicvoidonTabReselected(TabLayout.Tab tab) {

      }
    });

  }

  /*
   * Used to scroll to the given view.
   *
   * @param view View to which we need to scroll.
   */privatevoidscrollToView(View view) {
    // Get deepChild Offsetintposition= getRelativeTop(view);
    finalintfinalPosition= position;
    nestedScrollView.fling(0);
    nestedScrollView.smoothScrollTo(0, finalPosition);
  }

  privateintgetRelativeTop(View myView) {
    RectoffsetViewBounds=newRect();
//returns the visible bounds
    myView.getDrawingRect(offsetViewBounds);
// calculates the relative coordinates to the parent
    coordinatorLayout.offsetDescendantRectToMyCoords(myView, offsetViewBounds);

    intrelativeTop= offsetViewBounds.top;
    intrelativeLeft= offsetViewBounds.left;
    return relativeTop;
  }

}

Solution 4:

You can try this:

nestedScrollView.fling(0);
nestedScrollView.smoothScrollTo(0, 0);