Android - How to add parallax effect as bottom sheet covers another view

Android - How to add parallax effect as bottom sheet covers another view - android

Using BottomSheetBehavior from the google design library, it looks like the default behavior is for the bottom sheet to "cover" other views in the same CoordinatorLayout as it expands. I can anchor something like a FAB (or other view with an appropriately defined CoordinatorLayout.Behavior) to the top of the sheet and have it slide up as the sheet expands, which is nice, but what I want is to have a view "collapse" as the bottom sheet expands, showing a parallax effect.
This effect in Google Maps is similar to what I'm looking for; it starts as a parallax effect, and then switches back to just having the bottom sheet "cover" the map once a certain scroll position is reached:
One thing I tried (though I suspected from the start it wouldn't work), was setting the upper view's height programmatically in the onSlide call of my BottomSheetBehavior.BottomSheetCallback. This was somewhat successful, but the movement wasn't nearly as smooth as in Google Maps.
If anyone has an idea how the effect is accomplished I would appreciate it a lot!

After a bit more experimenting/research I realized from this post
How to make custom CoordinatorLayout.Behavior with parallax scrolling effect for google MapView? that a big part of my problem was not understanding the parallax effect, which translates views rather than shrinking them. Once I realized that, it was trivial to create a custom behavior that would apply the parallax to my main view when the bottom sheet expanded:
public class CollapseBehavior<V extends ViewGroup> extends CoordinatorLayout.Behavior<V>{
public CollapseBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) {
if (isBottomSheet(dependency)) {
BottomSheetBehavior behavior = ((BottomSheetBehavior) ((CoordinatorLayout.LayoutParams) dependency.getLayoutParams()).getBehavior());
int peekHeight = behavior.getPeekHeight();
// The default peek height is -1, which
// gets resolved to a 16:9 ratio with the parent
final int actualPeek = peekHeight >= 0 ? peekHeight : (int) (((parent.getHeight() * 1.0) / (16.0)) * 9.0);
if (dependency.getTop() >= actualPeek) {
// Only perform translations when the
// view is between "hidden" and "collapsed" states
final int dy = dependency.getTop() - parent.getHeight();
ViewCompat.setTranslationY(child, dy/2);
return true;
}
}
return false;
}
private static boolean isBottomSheet(#NonNull View view) {
final ViewGroup.LayoutParams lp = view.getLayoutParams();
if (lp instanceof CoordinatorLayout.LayoutParams) {
return ((CoordinatorLayout.LayoutParams) lp)
.getBehavior() instanceof BottomSheetBehavior;
}
return false;
}
}
Then in my layout XML, I set the app:layout_behavior of my main view to be com.mypackage.CollapseBehavior and the app:layout_anchor to be my bottom sheet view so that the onDependentViewChanged callback would trigger. This effect was much smoother than trying to resize the view. I suspect returning to my initial strategy of using a BottomSheetBehavior.BottomSheetCallback would also work similarly to this solution.
Edit: per request, the relevant XML is below. I add a MapFragment into #+id/map_container at runtime, though this should also work with anything you drop into that container like a static image. The LocationListFragment could likewise be replaced with any view or fragment, so long as it still has the BottomSheetBehavior
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/fragment_coordinator">
<FrameLayout
android:id="#+id/map_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
app:layout_anchor="#+id/list_container"
app:layout_behavior="com.mypackage.behavior.CollapseBehavior"/>
<fragment
android:name="com.mypackage.fragment.LocationListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/list_container"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior"/>
</android.support.design.widget.CoordinatorLayout>

Patrick Grayson's post was very helpful. In my case though, I did need something that resized the map. I adopted the solution above to resize instead of translate. Perhaps others may be looking for a similar solution.
public class CollapseBehavior<V extends ViewGroup> extends CoordinatorLayout.Behavior<V> {
private int pixels = NO_RESIZE_BUFFER; // default value, in case getting a value from resources, bites the dust.
private static final int NO_RESIZE_BUFFER = 200; //The amount of dp to not have the bottom sheet ever push away.
public CollapseBehavior(Context context, AttributeSet attrs)
{
super(context, attrs);
pixels = (int)convertDpToPixel(NO_RESIZE_BUFFER,context);
}
#Override
public boolean onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) {
// child is the map
// dependency is the bottomSheet
if(isBottomSheet(dependency))
{
BottomSheetBehavior behavior = ((BottomSheetBehavior) ((CoordinatorLayout.LayoutParams)dependency.getLayoutParams()).getBehavior());
int peekHeight;
if (behavior != null) {
peekHeight = behavior.getPeekHeight();
}
else
return true;
if(peekHeight > 0) { // Dodge the case where the sheet is hidden.
if (dependency.getTop() >= peekHeight) { // Otherwise we'd completely overlap the map
if(dependency.getTop() >= pixels) { // On resize when we have more than our NO_RESIZE_BUFFER of dp left.
if(dependency.getTop() > 0) { // Don't want to map to be gone completely.
CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
params.height = dependency.getTop();
child.setLayoutParams(params);
}
return true;
}
}
}
}
return false;
}
private static float convertDpToPixel(float dp, Context context)
{
float densityDpi = context.getResources().getDisplayMetrics().densityDpi;
return dp * (densityDpi / DisplayMetrics.DENSITY_DEFAULT);
}
private static boolean isBottomSheet(#NonNull View view)
{
final ViewGroup.LayoutParams lp = view.getLayoutParams();
if(lp instanceof CoordinatorLayout.LayoutParams)
{
return ((CoordinatorLayout.LayoutParams) lp).getBehavior() instanceof BottomSheetBehavior;
}
return false;
}
}
And the layout...
<FrameLayout
android:id="#+id/flMap"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="top"
android:layout_margin="0dp"
app:layout_anchor="#+id/persistentBottomSheet"
app:layout_behavior="com.yoursite.yourapp.CollapseBehavior">
<fragment
android:id="#+id/mapDirectionSummary"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.yoursite.yourapp.YourActivity" />
</FrameLayout>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/persistentBottomSheet"
app:behavior_peekHeight="#dimen/bottom_sheet_peek_height"
app:behavior_hideable="false"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
tools:context="com.yoursite.yourapp.YourActivity">
<!-- Whatever you want on the bottom sheet. -->
</android.support.constraint.ConstraintLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
app:cardElevation="8dp"
app:cardBackgroundColor="#324">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="56dp"
android:background="?attr/colorPrimary"
android:theme="#style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="#style/Theme.AppCompat.Light">
<EditText
android:id="#+id/txtSearch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
android:ems="10"
android:inputType="text"
android:maxLines="1" />
</android.support.v7.widget.Toolbar>
</android.support.v7.widget.CardView>
</LinearLayout>

Related

Pin a view to bottom of screen in BottomSheetDialog Fragment

I've used BottomSheetDialogFragment in my project and I've designed it as below:
Target: I'm going to stick the bottom menu of BottomSheetDialog to bottom of the screen, in either mode collapse and expand.
So in BottomSheetDialog layout, I used RelativeLayout for parent and "layout_alignParentBottom" for menu container, As below:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/bottomSheetContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
app:behavior_hideable="true"
app:behavior_peekHeight="0dp"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
tools:context=".MyBottomSheetDialogFragment">
<RelativeLayout
android:id="#+id/topSection"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true">
....
</RelativeLayout>
<android.support.v4.widget.NestedScrollView
android:id="#+id/descriptionContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/topSection">
....
</android.support.v4.widget.NestedScrollView>
<HorizontalScrollView
android:id="#+id/iconsContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true">
....
</HorizontalScrollView>
</RelativeLayout>
But the dialogue is as follows:
As you can see, the bottom menu is not visible at first.
Can someone help me to solve this problem?

To solve this, several things came to my mind when I tried, but I did not succeed.
But this finally solved for me by this way:
For collapse mode, I set the bottomSheetBehavior's peekHeight to 1/3 of the screen (with the following code):
View bottomSheetContainer = dialog.findViewById(R.id.bottomSheetContainer);
View parent = (View) bottomSheetContainer.getParent();
CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) parent.getLayoutParams();
BottomSheetBehavior bottomSheetBehavior = (BottomSheetBehavior) params.getBehavior();
View inflatedView = View.inflate(getContext(), R.layout.word_details_bottom_sheet, null);
inflatedView.measure(0, 0);
int screenHeight = getActivity().getResources().getDisplayMetrics().heightPixels;
if (bottomSheetBehavior != null) {
bottomSheetBehavior.setPeekHeight(screenHeight /3);
}
So I decided to do it:
1- for collapse mode: bottomSheet container's height = bottomSheetBehavior's peekHeight
2- for expand mode: bottomSheet container's height = full screen Height
So I wrote the following code (full code):
WordDetailsBottomSheet.java
public class WordDetailsBottomSheet extends BottomSheetDialogFragment {
public WordDetailsBottomSheet() { // Required empty public constructor }
#NotNull
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
BottomSheetDialog dialog = new BottomSheetDialog(getActivity(), 0);
dialog.setContentView(R.layout.word_details_bottom_sheet);
View bottomSheetContainer = dialog.findViewById(R.id.bottomSheetContainer);
View parent = (View) bottomSheetContainer.getParent();
CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) parent.getLayoutParams();
BottomSheetBehavior bottomSheetBehavior = (BottomSheetBehavior) params.getBehavior();
View inflatedView = View.inflate(getContext(), R.layout.word_details_bottom_sheet, null);
inflatedView.measure(0, 0);
int screenHeight = getActivity().getResources().getDisplayMetrics().heightPixels;
int statusBarHeight = getStatusBarHeight();
if (bottomSheetBehavior != null) {
bottomSheetBehavior.setPeekHeight(screenHeight / BOTTOM_SHEET_PEEK_HEIGHT_PERCENT);
bottomSheetContainer.getLayoutParams().height = bottomSheetBehavior.getPeekHeight();
}
bottomSheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
#Override
public void onStateChanged(#NonNull View view, int newState) {
switch (newState) {
case BottomSheetBehavior.STATE_EXPANDED:
bottomSheetContainer.getLayoutParams().height = screenHeight-statusBarHeight;
break;
case BottomSheetBehavior.STATE_COLLAPSED:
bottomSheetContainer.getLayoutParams().height = bottomSheetBehavior.getPeekHeight();
break;
case BottomSheetBehavior.STATE_HIDDEN:
dismiss();
break;
default:
break;
}
}
#Override
public void onSlide(#NonNull View view, float slideOffset) {
}
});
return dialog;
}
public int getStatusBarHeight() {
int result = 0;
int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
if (resourceId > 0) {
result = getResources().getDimensionPixelSize(resourceId);
}
return result;
}
}
word_details_bottom_sheet.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/bottomSheetContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
app:behavior_hideable="true"
app:behavior_peekHeight="0dp"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
tools:context=".MyBottomSheetDialogFragment">
<RelativeLayout
android:id="#+id/topSection"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true">
....
</RelativeLayout>
<android.support.v4.widget.NestedScrollView
android:id="#+id/descriptionContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/topSection">
....
</android.support.v4.widget.NestedScrollView>
<HorizontalScrollView
android:id="#+id/iconsContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true">
....
</HorizontalScrollView>
</RelativeLayout>
In the xml file, things that matter are:
1- parent id (android:id="#+id/bottomSheetContainer")
2- iconsContainer align (android:layout_alignParentBottom="true")

As you can see, the bottom menu is not visible at first.
Can someone help me to solve this problem?
I'm guessing that this behavior is working perfectly and fine because you set layout_height of NestedScrollView (Center content) to wrap_content which means, it will be wrapped by the content inside.
Meanwhile;
android:layout_alignParentBottom="true"
To HorizontalScrollView (below layout) means that it will be under the other layouts which it currently is!
So, if you are trying to see if it is working fine or not, set 100dp-50dp (or a specific size which you can see when BottomSheetDialog show up) instead of wrap_content to NestedScrollView then you probably would see that the below layout with the other layouts will be visible.
Anyways, everything's in this layout looks correct and fine. As well as pictures says the truth.

How to avoid blocking of scrolling itself when using setNestedScrollingEnabled(false)?

Background
We have quite a complex layout that has CollapsingToolbarLayout in it, together with a RecyclerView at the bottom.
In certain cases, we temporarily disable the expanding/collapsing of the CollapsingToolbarLayout, by calling setNestedScrollingEnabled(boolean) on the RecyclerView.
The problem
This usually works fine.
However, on some (bit rare) cases, slow scrolling on the RecyclerView gets semi-blocked, meaning it tries to scroll back when scrolling down. It's as if it has 2 scrolling that fight each other (scroll up and scroll down):
The code to trigger this is as such:
res/layout/activity_scrolling.xml
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.user.myapplication.ScrollingActivity">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="#style/AppTheme.PopupOverlay"/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/nestedView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_anchor="#id/app_bar"
app:layout_anchorGravity="bottom|end">
<Button
android:id="#+id/disableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="disable"/>
<Button
android:id="#+id/enableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="enable"
/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
ScrollingActivity.java
public class ScrollingActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scrolling);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final RecyclerView nestedView = (RecyclerView) findViewById(R.id.nestedView);
findViewById(R.id.disableNestedScrollingButton).setOnClickListener(new OnClickListener() {
#Override
public void onClick(final View v) {
nestedView.setNestedScrollingEnabled(false);
}
});
findViewById(R.id.enableNestedScrollingButton).setOnClickListener(new OnClickListener() {
#Override
public void onClick(final View v) {
nestedView.setNestedScrollingEnabled(true);
}
});
nestedView.setLayoutManager(new LinearLayoutManager(this));
nestedView.setAdapter(new Adapter() {
#Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
return new ViewHolder(LayoutInflater.from(parent.getContext()).inflate(
android.R.layout.simple_list_item_1,
parent,
false)) {
};
}
#Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
((TextView) holder.itemView.findViewById(android.R.id.text1)).setText("item " + position);
}
#Override
public int getItemCount() {
return 100;
}
});
}
}
What I've tried
At first I thought it's because of something else (I thought it's a weird combination with DrawerLayout), but then I've found a minimal sample to show it, and it's just as I thought: it's all because of the setNestedScrollingEnabled.
I tried to report about this on Google's website (here), hoping it will get fixed if it's a real bug. If you wish to try it out, or watch the videos of the issue, go there, as I can't upload them all here (too large and too many files).
I've also tried to use special flags as instructed on other posts (examples: here, here, here, here and here) , but none helped. In fact each of them had an issue, whether it's staying in expanded mode, or scrolling in a different way than what I do.
The questions
Is this a known issue? Why does it happen?
Is there a way to overcome this?
Is there perhaps an alternative to calling this function of setNestedScrollingEnabled ? One without any issues of scrolling or locking the state of the CollapsingToolbarLayout ?

This is an alternate approach to achieving the same goal as this answer. While that answer used Reflection, this answer does not, but the reasoning remains the same.
Why is this happening?
The problem is that RecyclerView sometimes uses a stale value for the member variable mScrollOffset. mScrollOffset is set in only two places in RecyclerView: dispatchNestedPreScroll and dispatchNestedScroll. We are only concerned with dispatchNestedPreScroll. This method is invoked by RecyclerView#onTouchEvent when it handles MotionEvent.ACTION_MOVE events.
The following is from the documentation for dispatchNestedPreScroll.
dispatchNestedPreScroll
boolean dispatchNestedPreScroll (int dx,
int dy,
int[] consumed,
int[] offsetInWindow)
Dispatch one step of a nested scroll in progress before this view consumes any portion of it.
Nested pre-scroll events are to nested scroll events what touch intercept is to touch. dispatchNestedPreScroll offers an opportunity for the parent view in a nested scrolling operation to consume some or all of the scroll operation before the child view consumes it.
...
offsetInWindow int: Optional. If not null, on return this will contain the offset in local view coordinates of this view from before this operation to after it completes. View implementations may use this to adjust expected input coordinate tracking.
offsetInWindow is actually an int[2] with the second index representing the y shift to be applied to the RecyclerView due to nested scrolling.
RecyclerView#DispatchNestedPrescroll resolves to a method with the same name in NestedScrollingChildHelper.
When RecyclerView calls dispatchNestedPreScroll,
mScrollOffset is used as the offsetInWindow argument. So any changes made to offsetInWindow directly updates mScrollOffset. dispatchNestedPreScroll updates mScrollOffset as long as nested scrolling is in effect. If nested scrolling is not in effect, then mScrollOffset is not updated and proceeds with the value that was last set by dispatchNestedPreScroll. Thus, when nested scrolling is turned off, the value of mScrollOffset becomes immediately stale but RecyclerView continues to use it.
The correct value of mScrollOffset[1] upon return from dispatchNestedPreScroll is the amount to adjust for input coordinate tracking (see above). In RecyclerView the following lines adjusts the y touch coordinate:
mLastTouchY = y - mScrollOffset[1];
If mScrollOffset[1] is, let's say, -30 (because it is stale and should be zero) then mLastTouchY will be off by +30 pixels (--30=+30). The effect of this miscalculation is that it will appear that the touch occurred further down the screen than it really did. So, a slow downward scroll will actually scrolls up and an upward scroll will scroll faster. (If a downward scroll is fast enough to overcome this 30px barrier, then downward scrolling will occur but more slowly than it should.) Upward scrolling will be overly quick since the app thinks more space has been covered.
mScrollOffset will continue as a stale variable until nested scrolling is turned on and dispatchNestedPreScroll once again reports the correct value in mScrollOffset.
Approach
Since mScrollOffset[1] has a stale value under certain circumstances, the goal is to set it to the correct value under those circumstances. This value should be zero when nested scrolling is not taking place, i.e., When the AppBar is expanded or collapsed. Unfortunately, mScrollOffset is local to RecyclerView and there is no setter for it. To gain access to mScrollOffset without resorting to Reflection, a custom RecyclerView is created that overrides dispatchNestedPreScroll. The fourth agument is offsetInWindow which is the variable we need to change.
A stale mScrollOffset occurs whenever nested scrolling is disabled for the RecyclerView. An additional condition we will impose is that the AppBar must be idle so we can safely say that mScrollOffset[1] should be zero. This is not an issue since the CollapsingToolbarLayout specifies snap in the scroll flags.
In the sample app, ScrollingActivity has been modified to record when the AppBar is expanded and closed. A callback has also been created (clampPrescrollOffsetListener) that will return true when our two conditions are met. Our overridden dispatchNestedPreScroll will invoke this callback and clamp mScrollOffset[1] to zero on a true response.
The updated source file for ScrollingActivity is presented below as is the custom RecyclerView - MyRecyclerView.
The XML layout file must be changed to reflect the custom MyRecyclerView.
ScrollingActivity
public class ScrollingActivity extends AppCompatActivity
implements MyRecyclerView.OnClampPrescrollOffsetListener {
private CollapsingToolbarLayout mCollapsingToolbarLayout;
private AppBarLayout mAppBarLayout;
private MyRecyclerView mNestedView;
// This variable will be true when the app bar is completely open or completely collapsed.
private boolean mAppBarIdle = true;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scrolling);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mNestedView = (MyRecyclerView) findViewById(R.id.nestedView);
mAppBarLayout = (AppBarLayout) findViewById(R.id.app_bar);
mCollapsingToolbarLayout = (CollapsingToolbarLayout) findViewById(R.id.toolbar_layout);
// Set the listener for the patch code.
mNestedView.setOnClampPrescrollOffsetListener(this);
// Listener to determine when the app bar is collapsed or fully open (idle).
mAppBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
#Override
public final void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
mAppBarIdle = verticalOffset == 0
|| verticalOffset <= appBarLayout.getTotalScrollRange();
}
});
findViewById(R.id.disableNestedScrollingButton).setOnClickListener(new OnClickListener() {
#Override
public void onClick(final View v) {
// If the AppBar is fully expanded or fully collapsed (idle), then disable
// expansion and apply the patch; otherwise, set a flag to disable the expansion
// and apply the patch when the AppBar is idle.
setExpandEnabled(false);
}
});
findViewById(R.id.enableNestedScrollingButton).setOnClickListener(new OnClickListener() {
#Override
public void onClick(final View v) {
setExpandEnabled(true);
}
});
mNestedView.setLayoutManager(new LinearLayoutManager(this));
mNestedView.setAdapter(new Adapter() {
#Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
return new ViewHolder(LayoutInflater.from(parent.getContext()).inflate(
android.R.layout.simple_list_item_1,
parent,
false)) {
};
}
#Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
((TextView) holder.itemView.findViewById(android.R.id.text1)).setText("item " + position);
}
#Override
public int getItemCount() {
return 100;
}
});
}
private void setExpandEnabled(boolean enabled) {
mNestedView.setNestedScrollingEnabled(enabled);
}
// Return "true" when the app bar is idle and nested scrolling is disabled. This is a signal
// to the custom RecyclerView to clamp the y prescroll offset to zero.
#Override
public boolean clampPrescrollOffsetListener() {
return mAppBarIdle && !mNestedView.isNestedScrollingEnabled();
}
private static final String TAG = "ScrollingActivity";
}
MyRecyclerView
public class MyRecyclerView extends RecyclerView {
private OnClampPrescrollOffsetListener mPatchListener;
public MyRecyclerView(Context context) {
super(context);
}
public MyRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyRecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
// Just a call to super plus code to force offsetInWindow[1] to zero if the patchlistener
// instructs it.
#Override
public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
boolean returnValue;
int currentOffset;
returnValue = super.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
currentOffset = offsetInWindow[1];
Log.d(TAG, "<<<<dispatchNestedPreScroll: " + currentOffset);
if (mPatchListener.clampPrescrollOffsetListener() && offsetInWindow[1] != 0) {
Log.d(TAG, "<<<<dispatchNestedPreScroll: " + currentOffset + " -> 0");
offsetInWindow[1] = 0;
}
return returnValue;
}
public void setOnClampPrescrollOffsetListener(OnClampPrescrollOffsetListener patchListener) {
mPatchListener = patchListener;
}
public interface OnClampPrescrollOffsetListener {
boolean clampPrescrollOffsetListener();
}
private static final String TAG = "MyRecyclerView";
}

Actually, you might be looking at the problem in the wrong way.
The only thing you need is to set the Toolbar flags accordingly. You don't really anything else so I would say that your layout should be simplified to:
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.user.myapplication.ScrollingActivity">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/AppTheme.PopupOverlay"
app:title="Title" />
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/nestedView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_anchor="#id/app_bar"
app:layout_anchorGravity="bottom|end">
<Button
android:id="#+id/disableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="disable"/>
<Button
android:id="#+id/enableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="enable"
/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
Then when you wish to disable the collapsing just set your toolbar flags:
// To disable collapsing
AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
params.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SNAP);
toolbar.setLayoutParams(params);
And to enable
// To enable collapsing
AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
params.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL|AppBarLayout.LayoutParams.SCROLL_FLAG_ENTER_ALWAYS);
toolbar.setLayoutParams(params);
Hold a reference to the layout params if you are changing instead of getting it all the time.
If you need to have the CollapsingToolbarLayout get from and set the LayoutParams to that View instead, update the flags the same way but now adding the appBarLayout.setExpanded(true/false)
Note: Using the setScrollFlags clears all previous flags, so be careful and set all required flags when using this method.

As #Moinkhan points out, you could try wrapping the RecyclerView and next elements in a NestedScrollView like this, this should resolve your problem of scrolling alongside with your collapsing toolbar layout:
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.user.myapplication.ScrollingActivity">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="#style/AppTheme.PopupOverlay"/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="fill_vertical"
android:fillViewport="true"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/nestedView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
</RelativeLayout>
</android.support.v4.widget.NestedScrollView>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_anchor="#id/app_bar"
app:layout_anchorGravity="bottom|end">
<Button
android:id="#+id/disableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="disable"/>
<Button
android:id="#+id/enableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="enable"
/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
In case the contents of the recyclerview are not displayed you can follow this thread to solve that issue How to use RecyclerView inside NestedScrollView?.
Hope it helps.

inside the recycler view, to scrolling smooth
android:nestedScrollingEnabled="false"
to overlap the cardView in the toolbar
app:behavior_overlapTop = "24dp"
Try this code for CollapsingToolbar:
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/background"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="#style/AppTheme.PopupOverlay"
app:title="Title" />
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:background="#android:color/transparent"
app:behavior_overlapTop="#dimen/behavior_overlap_top"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="#dimen/text_min_padding"
android:nestedScrollingEnabled="false"
android:scrollbarSize="2dp"
android:scrollbarStyle="outsideInset"
android:scrollbarThumbVertical="#color/colorAccent"
android:scrollbars="vertical" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>
Screenshot

I had to solve a similar issue and did it using a custom behaviour on the AppBarLayout. Everything works great.
By overriding onStartNestedScroll in the custom behaviour it is possible to block to collapsing toolbar layout from expanding or collapsing while keeping the scroll view (NestedScrollView) in my case, working as expected. I explained the details here, hope it helps.
private class AppBarLayoutBehavior : AppBarLayout.Behavior() {
var canDrag = true
var acceptsNestedScroll = true
init {
setDragCallback(object : AppBarLayout.Behavior.DragCallback() {
override fun canDrag(appBarLayout: AppBarLayout): Boolean {
// Allow/Do not allow dragging down/up to expand/collapse the layout
return canDrag
}
})
}
override fun onStartNestedScroll(parent: CoordinatorLayout,
child: AppBarLayout,
directTargetChild: View,
target: View,
nestedScrollAxes: Int,
type: Int): Boolean {
// Refuse/Accept any nested scroll event
return acceptsNestedScroll
}}

Use following code, it works fine for me:
lockAppBarClosed();
ViewCompat.setNestedScrollingEnabled(recyclerView, false); // to lock the CollapsingToolbarLayout
and implement the following methods:
private void setAppBarDragging(final boolean isEnabled) {
CoordinatorLayout.LayoutParams params =
(CoordinatorLayout.LayoutParams) appBarLayout.getLayoutParams();
AppBarLayout.Behavior behavior = new AppBarLayout.Behavior();
behavior.setDragCallback(new AppBarLayout.Behavior.DragCallback() {
#Override
public boolean canDrag(AppBarLayout appBarLayout) {
return isEnabled;
}
});
params.setBehavior(behavior);
}
public void unlockAppBarOpen() {
appBarLayout.setExpanded(true, false);
appBarLayout.setActivated(true);
setAppBarDragging(false);
}
public void lockAppBarClosed() {
appBarLayout.setExpanded(false, false);
appBarLayout.setActivated(false);
setAppBarDragging(false);
}

I believe that this problem is related to the collapsing toolbar snapping into place (either closed or open) and leaving a vertical offset variable (mScrollOffset[1] in RecyclerView) with a non-zero value that subsequently biases the scroll - slowing or reversing the scroll in one direction and speeding it up in the other. This variable only seems to be set in NestedScrollingChildHelper if nested scrolling is enabled. So, whatever value mScrollOffset[1] has goes unchanged once nest scrolling is disabled.
To reliably reproduce this issue, you can cause the toolbar to snap into place then immediately click disable. See this video for a demonstration. I believe, that the magnitude of the issue varies by how much "snapping" occurs.
If I drag the toolbar to the fully open or closed position and don't let it "snap", then I have not been able to reproduce this problem and mScrollOffset[1] is set to zero which I think is the right value. I have also reproduced the problem by removing snap from the layout_scrollFlags of the collapsing toolbar in the layout and placing the toolbar in a partially open state.
If you want to play around with this, you can put your demo app into debug mode and observe the value of mScrollOffset[1] in RecyclerView#onTouchEvent. Also take a look at NestedScrollingChildHelper's dispatchNestedScroll and dispatchNestedPreScroll methods to see how the offset is set only when nested scrolling is enabled.
So, how to fix this? mScrollOffset is private toRecyclerView and it is not immediately obvious how to subclass anything to change the value of mScrollOffset[1]. That would leave Reflection, but that may not be desirable to you. Maybe another reader has an idea about how to approach this or knows of some secret sauce. I will repost if anything occurs to me.
Edit: I have provided a new ScrollingActivity.java class that overcomes this issue. It does use reflection and applies a patch to set mScrollOffset[1] of RecyclerView to zero when the disable scroll button has been pressed and the AppBar is idle. I have done some preliminary testing and it is working. Here is the gist. (See updated gist below.)
Second edit: I was able to get the toolbar to snap in funny ways and get stuck in the middle without the patch, so it doesn't look like the patch is causing that particular issue. I can get the toolbar to bounce from fully open to collapsed by scrolling down fast enough in the unpatched app.
I also took another look at what the patch is doing and I think that it will behave itself: The variable is private and referred to only in one place after scrolling is turned off. With scrolling enabled, the variable is always reset before use. The real answer is for Google to fix this problem. Until they do, I think this may be the closest you can get to an acceptable work-around with this particular design. (I have posted an updated gist that addresses potential issues with a quick click-around leaving switches in a potential unsuitable state.)
Regardless, the underlying issue has been identified and you have a reliable way to reproduce the problem, so you can more easily verify other proposed solutions.
I hope this helps.

I want to present a nice alternative, mainly based on the one here :
AppBarLayoutEx.kt
class AppBarLayoutEx : AppBarLayout {
private var isAppBarExpanded = true
private val behavior = AppBarLayoutBehavior()
private var onStateChangedListener: (Boolean) -> Unit = {}
var enableExpandAndCollapseByDraggingToolbar: Boolean
get() = behavior.canDrag
set(value) {
behavior.canDrag = value
}
var enableExpandAndCollapseByDraggingContent: Boolean
get() = behavior.acceptsNestedScroll
set(value) {
behavior.acceptsNestedScroll = value
}
constructor(context: Context) : super(context)
constructor(context: Context, attrs: AttributeSet) : super(context, attrs)
init {
addOnOffsetChangedListener(
AppBarLayout.OnOffsetChangedListener { _, verticalOffset ->
isAppBarExpanded = verticalOffset == 0
onStateChangedListener(isAppBarExpanded)
})
}
override fun setLayoutParams(params: ViewGroup.LayoutParams?) {
super.setLayoutParams(params)
(params as CoordinatorLayout.LayoutParams).behavior = behavior
}
fun toggleExpandedState() {
setExpanded(!isAppBarExpanded, true)
}
fun setOnExpandAndCollapseListener(onStateChangedListener: (Boolean) -> Unit) {
this.onStateChangedListener = onStateChangedListener
}
private class AppBarLayoutBehavior : AppBarLayout.Behavior() {
var canDrag = true
var acceptsNestedScroll = true
init {
setDragCallback(object : AppBarLayout.Behavior.DragCallback() {
override fun canDrag(appBarLayout: AppBarLayout) = canDrag
})
}
override fun onStartNestedScroll(parent: CoordinatorLayout, child: AppBarLayout, directTargetChild: View,
target: View, nestedScrollAxes: Int, type: Int) = acceptsNestedScroll
}
}
Usage: besides using it in the layout XML file, you can disable/enable the expanding of it using:
appBarLayout.enableExpandAndCollapseByDraggingToolbar = true/false
appBarLayout.enableExpandAndCollapseByDraggingContent = true/false

How to use BottomSheetDialog?

I want to try BottomSheetDialog introduced in Android Support Library 23.2 but it doesn't seem to work correctly. Here is what the doc says:
While BottomSheetBehavior captures the persistent bottom sheet case, this release also provides a BottomSheetDialog and
BottomSheetDialogFragment to fill the modal bottom sheets use case.
Simply replace AppCompatDialog or AppCompatDialogFragment with their
bottom sheet equivalents to have your dialog styled as a bottom
sheet."
So I changed my AppCompatDialog to BottomSheetDialog:
package my.package.ui.dialog;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.design.widget.BottomSheetDialog;
import my.package.R;
public class AccountActionsDialog extends BottomSheetDialog {
public AccountActionsDialog(Context context) {
super(context);
if (context instanceof Activity) {
setOwnerActivity((Activity) context);
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getLayoutInflater().inflate(R.layout.dialog_account_actions, null));
}
}
Here is my layout file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ff0000"
android:padding="16dp"
android:text="Delete account"
android:textColor="#ffffff" />
</LinearLayout>
Then I use the following code in my Activity:
new AccountActionsDialog(this).show();
My screen becomes dimmed but the content of my dialog is not visible. Any thoughts on what might be missing? It works fine when I use AppCompatDialog instead.

Instead of having a separate class, you can simply create an instance for BottomSheetDialog in your Activity/Fragment like following and you can use it. It is very easier and simpler I think.
val dialog = BottomSheetDialog(this)
val bottomSheet = layoutInflater.inflate(R.layout.bottom_sheet, null)
bottomSheet.buttonSubmit.setOnClickListener { dialog.dismiss() }
dialog.setContentView(bottomSheet)
dialog.show()

This is the layout file of BottomSheetDialog.
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:soundEffectsEnabled="false">
<FrameLayout
android:id="#+id/design_bottom_sheet"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
app:layout_behavior="#string/bottom_sheet_behavior"
style="?attr/bottomSheetStyle"/>
</android.support.design.widget.CoordinatorLayout>
Your content view is inside the view design_bottom_sheet, it will be positioned center vertically by CoordinatorLayout, and BottomSheetBehavior will offset it.
mParentHeight = parent.getHeight();
mMinOffset = Math.max(0, mParentHeight - child.getHeight());
mMaxOffset = mParentHeight - mPeekHeight;
if (mState == STATE_EXPANDED) {
ViewCompat.offsetTopAndBottom(child, mMinOffset);
} else if (mHideable && mState == STATE_HIDDEN) {
ViewCompat.offsetTopAndBottom(child, mParentHeight);
} else if (mState == STATE_COLLAPSED) {
ViewCompat.offsetTopAndBottom(child, mMaxOffset);
}
It intented to positon design_bottom_sheet at mMaxOffset, but actually the initial getTop of the child view is not 0, but (mParentHeight - childHeight) / 2, so you view if offset more than the desired offset.
Find the view design_bottom_sheet and set its gravity to Gravity.TOP | Gravity.CENTER_HORIZONTAL will fix it. But, if the childHeight is less than mPeekHeight, there will be blank area below you content view.
However, if peekHeight > childHeight, the mMaxOffset will less than mMinOffset, which will cause weird behavior.
Maybe the code should be changed to
mMaxOffset = Math.max((mParentHeight - mPeekHeight), mMinOffset);
insted of
mMaxOffset = mParentHeight - child.getHeight();

Here's the issue on code.google.com https://code.google.com/p/android/issues/detail?id=201793
An issue some users are seeing boils down to the FrameLayout that wraps our content view being centered vertically. The BottomSheetBehavior only works if this view is top aligned. I haven't figured out what causes the FrameLayout to become centered vertically yet, but here's a possible workaround:
View contentView = ...
// You may have to measure your content view first.
dialog.setContentView(contentView);
// Change this to a percentage or a constant, whatever you want to do.
// The default is 1024 - any views smaller than this will be pulled off
// the bottom of the screen.
float peekHeight = contentView.getMeasuredHeight();
View parent = (View)contentView.getParent();
BottomSheetBehavior behavior = BottomSheetBehavior.from(parent);
behavior.setPeekHeight(peekHeight);
CoordinatorLayout.LayoutParams layoutParams =
(CoordinatorLayout.LayoutParams)parent.getLayoutParams();
layoutParams.gravity = Gravity.TOP | Gravity.CENTER_HORIZONTAL;

I was expriencing the same issue, dimmed background and content not visible. Here is how I managed to workaround it by setting the content view in setupDialog() hidden method.
public class CustomBottomSheetDialogFragment extends BottomSheetDialogFragment {
private TextView mOffsetText;
private TextView mStateText;
private BottomSheetBehavior.BottomSheetCallback mBottomSheetBehaviorCallback = new BottomSheetBehavior.BottomSheetCallback() {
#Override
public void onStateChanged(#NonNull View bottomSheet, int newState) {
setStateText(newState);
if (newState == BottomSheetBehavior.STATE_HIDDEN) {
dismiss();
}
}
#Override
public void onSlide(#NonNull View bottomSheet, float slideOffset) {
setOffsetText(slideOffset);
}
};
private LinearLayoutManager mLinearLayoutManager;
private ApplicationAdapter mAdapter;
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return super.onCreateDialog(savedInstanceState);
}
#Override
public void onViewCreated(View contentView, #Nullable Bundle savedInstanceState) {
super.onViewCreated(contentView, savedInstanceState);
}
#Override
public void setupDialog(Dialog dialog, int style) {
super.setupDialog(dialog, style);
View contentView = View.inflate(getContext(), R.layout.bottom_sheet_dialog_content_view, null);
dialog.setContentView(contentView);
mBottomSheetBehavior = BottomSheetBehavior.from(((View) contentView.getParent()));
if (mBottomSheetBehavior != null) {
mBottomSheetBehavior.setBottomSheetCallback(mBottomSheetBehaviorCallback);
}
mOffsetText = (TextView) contentView.findViewById(R.id.offsetText);
mStateText = (TextView) contentView.findViewById(R.id.stateText);
}
}
And the layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/offsetText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#android:color/black" />
<TextView
android:id="#+id/stateText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#android:color/black" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>

It started to work when I set fixed height for my TextView (200dp), although for some height values it still behaves incorrectly. Obviously it's an issue of support lib. There are already few reports related to BottomSheetDialog in the bug tracker:
https://code.google.com/p/android/issues/detail?id=201793&sort=-opened&colspec=ID%20Status%20Priority%20Owner%20Summary%20Stars%20Reporter%20Opened
https://code.google.com/p/android/issues/detail?id=201826

Android Layout: Horizontal Recyclerview inside a Vertical Recyclerview inside a Viewpager with Scroll Behaviors

This is the app I'm trying to build with all the elements mapped out below:
Everything works, however, I want the inner horizontal recyclerview not to capture any of the vertical scrolls. All vertical scrolls must go towards the outer vertical recyclerview, not the horizontal one, so that the vertical scroll would allow for the toolbar to exit out of view according to it's scrollFlag.
When I put my finger on the "StrawBerry Plant" part of the recyclerview and scroll up, it scroll out the toolbar:
If I put my finger on the horizontal scrollview and scroll up, it does not scroll out the toolbar at all.
The following is my xml layout code so far.
The Activity xml layout:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/fragment_container"
android:clipChildren="false">
<android.support.design.widget.CoordinatorLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/container"
>
<android.support.design.widget.AppBarLayout
android:id="#+id/appBarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:minHeight="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_scrollFlags="scroll|enterAlways">
</android.support.v7.widget.Toolbar>
<android.support.design.widget.TabLayout
android:id="#+id/sliding_tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
style="#style/CustomTabLayout"
/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
/>
</android.support.design.widget.CoordinatorLayout>
</FrameLayout>
The "Fruits" fragment xml layout (which is the code for the fragment - the fragment is labeled in the above picture):
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/progressBar"
android:visibility="gone"
android:layout_centerInParent="true"
android:indeterminate="true"/>
<!-- <android.support.v7.widget.RecyclerView-->
<com.example.simon.customshapes.VerticallyScrollRecyclerView
android:id="#+id/main_recyclerview"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
I have used a custom class called VerticallyScrollRecyclerView which follows google example of handling touch events in a viewgroup. Its aim is to intercept and consume all the vertical scroll events so that it will scroll in / out the toolbar: http://developer.android.com/training/gestures/viewgroup.html
The code for VerticallyScrollRecyclerView is below:
public class VerticallyScrollRecyclerView extends RecyclerView {
public VerticallyScrollRecyclerView(Context context) {
super(context);
}
public VerticallyScrollRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public VerticallyScrollRecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
ViewConfiguration vc = ViewConfiguration.get(this.getContext());
private int mTouchSlop = vc.getScaledTouchSlop();
private boolean mIsScrolling;
private float startY;
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
final int action = MotionEventCompat.getActionMasked(ev);
// Always handle the case of the touch gesture being complete.
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
// Release the scroll.
mIsScrolling = false;
startY = ev.getY();
return super.onInterceptTouchEvent(ev); // Do not intercept touch event, let the child handle it
}
switch (action) {
case MotionEvent.ACTION_MOVE: {
Log.e("VRecView", "its moving");
if (mIsScrolling) {
// We're currently scrolling, so yes, intercept the
// touch event!
return true;
}
// If the user has dragged her finger horizontally more than
// the touch slop, start the scroll
// left as an exercise for the reader
final float yDiff = calculateDistanceY(ev.getY());
Log.e("yDiff ", ""+yDiff);
// Touch slop should be calculated using ViewConfiguration
// constants.
if (Math.abs(yDiff) > 5) {
// Start scrolling!
Log.e("Scroll", "we are scrolling vertically");
mIsScrolling = true;
return true;
}
break;
}
}
return super.onInterceptTouchEvent(ev);
}
private float calculateDistanceY(float endY) {
return startY - endY;
}
}
The "Favourite" layout which is the recyclerview within the vertical recyclerview:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:background="#color/white"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Favourite"
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="16dp"
android:id="#+id/header_fav"/>
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_below="#+id/header_fav"
android:id="#+id/recyclerview_fav">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
This has been bugging me for a while now and I have not managed to come up with a solution. Does anyone know how to solve this problem?
5 points to Griffindor for the correct answer and of course, reputation points on SO.

Tested solution:
All you need is to call mInnerRecycler.setNestedScrollingEnabled(false); on your inner RecyclerViews
Explanation:
RecyclerView has support for nested scrolling introduced in API 21 through implementing the NestedScrollingChild interface. This is a valuable feature when you have a scrolling view inside another one that scrolls in the same direction and you want to scroll the inner View only when focused.
In any case, RecyclerView by default calls RecyclerView.setNestedScrollingEnabled(true); on itself when initializing. Now, back to the problem, since both of your RecyclerViews are within the same ViewPager that has the AppBarBehavior, the CoordinateLayout has to decide which scroll to respond to when you scroll from your inner RecyclerView; when your inner RecyclerView's nested scrolling is enabled, it gets the scrolling focus and the CoordinateLayout will choose to respond to its scrolling over the outer RecyclerView's scrolling. The thing is that, since your inner RecyclerViews don't scroll vertically, there is no vertical scroll change (from the CoordinateLayout's point of view), and if there is no change, the AppBarLayout doesn't change either.
In your case, because your inner RecyclerViews are scrolling in a different direction, you can disable it, thus causing the CoordinateLayout to disregard its scrolling and respond to the outer RecyclerView's scrolling.
Notice:
The xml attribute android:nestedScrollingEnabled="boolean" is not intended for use with the RecyclerView, and an attempt to use android:nestedScrollingEnabled="false" will result in a java.lang.NullPointerException so, at least for now, you will have to do it in code.

if any one still looking , try this :
private val Y_BUFFER = 10
private var preX = 0f
private var preY = 0f
mView.rv.addOnItemTouchListener(object : RecyclerView.OnItemTouchListener {
override fun onTouchEvent(p0: RecyclerView, p1: MotionEvent) {
}
override fun onInterceptTouchEvent(rv: RecyclerView, e: MotionEvent): Boolean {
when (e.action) {
MotionEvent.ACTION_DOWN -> rv.parent.requestDisallowInterceptTouchEvent(true)
MotionEvent.ACTION_MOVE -> {
if (Math.abs(e.x - preX) > Math.abs(e.y - preY)) {
rv.parent.requestDisallowInterceptTouchEvent(true)
} else if (Math.abs(e.y - preY) > Y_BUFFER) {
rv.parent.requestDisallowInterceptTouchEvent(false)
}
}
}
preX = e.x
preY = e.y
return false
}
override fun onRequestDisallowInterceptTouchEvent(p0: Boolean) {
}
})
it checks if currently scrolling horizontal then don't allow parent to handel event

I am a bit late but this will defintly work for others facing the same problem
mRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
#Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
int action = e.getAction();
// Toast.makeText(getActivity(),"HERE",Toast.LENGTH_SHORT).show();
switch (action) {
case MotionEvent.ACTION_POINTER_UP:
rv.getParent().requestDisallowInterceptTouchEvent(true);
break;
}
return false;
}

Tested solution, use a custom NestedScrollView().
Code:
public class CustomNestedScrollView extends NestedScrollView {
public CustomNestedScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
// Explicitly call computeScroll() to make the Scroller compute itself
computeScroll();
}
return super.onInterceptTouchEvent(ev);
}
}

try
public OuterRecyclerViewAdapter(List<Item> items) {
//Constructor stuff
viewPool = new RecyclerView.RecycledViewPool();
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//Create viewHolder etc
holder.innerRecyclerView.setRecycledViewPool(viewPool);
}
inner recylerview will use the same viewpool and it'll be smoother

I would suggest you add the horizontal recyclerview inside fragments like the google app

i read through the offered answers of using setNestedScrollingEnabled to false and it was awful for me as it makes the recyclerview not recycle and you can get crashes in memory, performance issues maybe etc if you have a huge list. so i will give you a algorithm to make it work without any code.
have a listener on the vertical recyclerview, such as a scroll listener. anytime the list is scrolled you will get a callback that its being scrolled. you should also get a call back when its idle.
now when vertical recylerview is being scrolled, setNestedScrollingEnabled = false on the horizontal list
once vertical recyclerview is idle setNestedScrollingEnabled = true on the same horizontal list.
also initially set the horizontal recyclerview to setNestedScrollingEnabled = false in xml
this can also work great also with appbarlayout when coordinatorLayout gets confused with two recyclerviews in different directions, but thats another question.
lets take a look at another more simple way in kotlin, to get this done with a real example. here we will focus just on the horizontal recyclerView:
assume we have RecyclerViewVertical & RecyclerViewHorizontal:
RecyclerViewHorizontal.apply {
addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
isNestedScrollingEnabled = RecyclerView.SCROLL_STATE_IDLE != newState
}
})
}
what this code says is if RecyclerViewHorizontal is not idle then enable nestedScrolling, otherwise disable it. That means when its idle we can now use the RecyclerViewVertical in a coordinatorlayout without any interference from the RecyclerViewHorizontal since we have disabled it when its idle.

Android - footer scrolls off screen when used in CoordinatorLayout

I have an AppBarLayout that scrolls off screen when scrolling a RecyclerView.
Below the RecyclerView there is a RelativeLayout that is a footer.
The footer is shown only after scrolling up - it behave like it has
layout_scrollFlags="scroll|enterAlways"
but it doesn't have any scroll flags - is it a bug or am I doing something wrong? I want it to be always visible
before scroll
after scroll
Update
opened a google issue on this - it was marked 'WorkingAsIntended' this still doesn't help because I want a working solution of a footer inside a fragment.
Update 2
you can find the activity and the fragment xmls here -
note that if line 34 in activity.xml - the line containing app:layout_behavior="#string/appbar_scrolling_view_behavior" is commented out the text end is visible from the start - otherwise, it is visible only after scrolling up

I use a simplified version of Learn OpenGL ES's solution (https://stackoverflow.com/a/33396965/778951) -- which improves on Noa's solution (https://stackoverflow.com/a/31140112/1317564). It works fine for my simple quick-return toolbar above a TabLayout with footer buttons in each tab's ViewPager content.
Just set the FixScrollingFooterBehavior as the layout_behavior on the View/ViewGroup you want to keep aligned at the bottom of the screen.
Layout:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?android:attr/actionBarSize"
android:minHeight="?android:attr/actionBarSize"
app:title="Foo"
app:layout_scrollFlags="scroll|enterAlways|snap"
/>
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMode="fixed"/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="com.spreeza.shop.ui.widgets.FixScrollingFooterBehavior"
/>
</android.support.design.widget.CoordinatorLayout>
Behavior:
public class FixScrollingFooterBehavior extends AppBarLayout.ScrollingViewBehavior {
private AppBarLayout appBarLayout;
public FixScrollingFooterBehavior() {
super();
}
public FixScrollingFooterBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
if (appBarLayout == null) {
appBarLayout = (AppBarLayout) dependency;
}
final boolean result = super.onDependentViewChanged(parent, child, dependency);
final int bottomPadding = calculateBottomPadding(appBarLayout);
final boolean paddingChanged = bottomPadding != child.getPaddingBottom();
if (paddingChanged) {
child.setPadding(
child.getPaddingLeft(),
child.getPaddingTop(),
child.getPaddingRight(),
bottomPadding);
child.requestLayout();
}
return paddingChanged || result;
}
// Calculate the padding needed to keep the bottom of the view pager's content at the same location on the screen.
private int calculateBottomPadding(AppBarLayout dependency) {
final int totalScrollRange = dependency.getTotalScrollRange();
return totalScrollRange + dependency.getTop();
}
}

Update
The solution below doesn't work for 5.1 as it works in 5 - instead of getTop use getTranslationY in any of the calculations you do.
layout.getTop()-->(int)layout.getTranslationY()
appbar.getTop()+toolbar.getHeight()-->(int)(appbar.getTranslationY()+toolbar.getHeight())
Update 2
with the new support library - 22.2.1 - there is no diff between 5.1 and prev versions, you should only use getTop and ignore the previous update in this answer
Original solution
After looking into many directions turns out the solution is actually simple - add paddingBottom to the fragment and adjust it as the page scrolls.
The padding is needed to cover for the changes in the toolbar y position - the coordinator layout is moving the entire page up and down as the toolbar disappears and reappears.
This can be achieved by extending AppBarLayout.ScrollingViewBehavior and setting this as the behavior of the fragment element of the activity.
Here are the basics of the code - it works for an activity with only a toolbar - you can replace it with appbar.getTop() + toolbar.getHeight() and this will work better if your appbar includes tabs.
activity.xml
<android.support.design.widget.CoordinatorLayout
android:id="#+id/main"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="3dp"
app:elevation="3dp">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_scrollFlags="scroll|enterAlways"
/>
</android.support.design.widget.AppBarLayout>
<fragment
android:id="#+id/fragment"
android:name="com.example.noa.footer2.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="com.example.noa.footer2.MyBehavior"
tools:layout="#layout/fragment"/>
</android.support.design.widget.CoordinatorLayout>
fragment.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="48dp"
android:background="#android:color/holo_green_dark"
tools:context=".MainActivityFragment">
<android.support.v7.widget.RecyclerView
android:id="#+id/list"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#null"/>
<View
android:layout_width="match_parent"
android:layout_height="100dp"
android:layout_alignParentBottom="true"
android:background="#android:color/holo_red_light"/>
</RelativeLayout>
MainActivityFragment#onActivityCreated
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
CoordinatorLayout.LayoutParams lp = (LayoutParams) getView().getLayoutParams();
MyBehavior behavior = (MyBehavior) lp.getBehavior();
behavior.setLayout(getView());
}
MyBehavior
public class MyBehavior extends AppBarLayout.ScrollingViewBehavior {
private View layout;
public MyBehavior() {
}
public MyBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
boolean result = super.onDependentViewChanged(parent, child, dependency);
if (layout != null) {
layout.setPadding(layout.getPaddingLeft(), layout.getPaddingTop(), layout
.getPaddingRight(), layout.getTop());
}
return result;
}
public void setLayout(View layout) {
this.layout = layout;
}
}

I started out with Noa's solution (https://stackoverflow.com/a/31140112/1317564) and it worked for finger drags, but I was running into trouble with flings. After spending some time to trace the method calls and trying out different ideas, here is the solution I ended up with:
// Workaround for https://code.google.com/p/android/issues/detail?id=177195
// Based off of solution originally found here: https://stackoverflow.com/a/31140112/1317564
#SuppressWarnings("unused")
public class CustomScrollingViewBehavior extends AppBarLayout.ScrollingViewBehavior {
private AppBarLayout appBarLayout;
private boolean onAnimationRunnablePosted = false;
#SuppressWarnings("unused")
public CustomScrollingViewBehavior() {
}
#SuppressWarnings("unused")
public CustomScrollingViewBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
if (appBarLayout != null) {
// We need to check from when a scroll is started, as we may not have had the chance to update the layout at
// the start of a scroll or fling event.
startAnimationRunnable(child, appBarLayout);
}
return super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
}
#Override
public boolean onMeasureChild(CoordinatorLayout parent, final View child, int parentWidthMeasureSpec, int widthUsed,
int parentHeightMeasureSpec, int heightUsed) {
if (appBarLayout != null) {
final int bottomPadding = calculateBottomPadding(appBarLayout);
if (bottomPadding != child.getPaddingBottom()) {
// We need to update the padding in onMeasureChild as otherwise we won't have the correct padding in
// place when the view is flung, and the changes done in onDependentViewChanged will only take effect on
// the next animation frame, which means it will be out of sync with the new scroll offset. This is only
// needed when the view is flung -- when dragged with a finger, things work fine with just
// implementing onDependentViewChanged().
child.setPadding(child.getPaddingLeft(), child.getPaddingTop(), child.getPaddingRight(), bottomPadding);
}
}
return super.onMeasureChild(parent, child, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
}
#Override
public boolean onDependentViewChanged(CoordinatorLayout parent, final View child, final View dependency) {
if (appBarLayout == null)
appBarLayout = (AppBarLayout) dependency;
final boolean result = super.onDependentViewChanged(parent, child, dependency);
final int bottomPadding = calculateBottomPadding(appBarLayout);
final boolean paddingChanged = bottomPadding != child.getPaddingBottom();
if (paddingChanged) {
// If we've changed the padding, then update the child and make sure a layout is requested.
child.setPadding(child.getPaddingLeft(),
child.getPaddingTop(),
child.getPaddingRight(),
bottomPadding);
child.requestLayout();
}
// Even if we didn't change the padding, if onDependentViewChanged was called then that means that the app bar
// layout was changed or was flung. In that case, we want to check for these changes over the next few animation
// frames so that we can ensure that we capture all the changes and update the view pager padding to match.
startAnimationRunnable(child, dependency);
return paddingChanged || result;
}
// Calculate the padding needed to keep the bottom of the view pager's content at the same location on the screen.
private int calculateBottomPadding(AppBarLayout dependency) {
final int totalScrollRange = dependency.getTotalScrollRange();
return totalScrollRange + dependency.getTop();
}
private void startAnimationRunnable(final View child, final View dependency) {
if (onAnimationRunnablePosted)
return;
final int onPostChildTop = child.getTop();
final int onPostDependencyTop = dependency.getTop();
onAnimationRunnablePosted = true;
// Start looking for changes at the beginning of each animation frame. If there are any changes, we have to
// ensure that layout is run again so that we can update the padding to take the changes into account.
child.postOnAnimation(new Runnable() {
private static final int MAX_COUNT_OF_FRAMES_WITH_NO_CHANGES = 5;
private int previousChildTop = onPostChildTop;
private int previousDependencyTop = onPostDependencyTop;
private int countOfFramesWithNoChanges;
#Override
public void run() {
// Make sure we request a layout at the beginning of each animation frame, until we notice a few
// frames where nothing changed.
final int currentChildTop = child.getTop();
final int currentDependencyTop = dependency.getTop();
boolean hasChanged = false;
if (currentChildTop != previousChildTop) {
previousChildTop = currentChildTop;
hasChanged = true;
countOfFramesWithNoChanges = 0;
}
if (currentDependencyTop != previousDependencyTop) {
previousDependencyTop = currentDependencyTop;
hasChanged = true;
countOfFramesWithNoChanges = 0;
}
if (!hasChanged) {
countOfFramesWithNoChanges++;
}
if (countOfFramesWithNoChanges <= MAX_COUNT_OF_FRAMES_WITH_NO_CHANGES) {
// We can still look for changes on subsequent frames.
child.requestLayout();
child.postOnAnimation(this);
} else {
// We've encountered enough frames with no changes. Do a final layout request, and don't repost.
child.requestLayout();
onAnimationRunnablePosted = false;
}
}
});
}
}
I'm not a fan of rechecking the layout on every animation frame, and this solution isn't perfect as I've seen some issues if programmatically expanding/collapsing the app bar layout, but for now I haven't found a better solution. The performance is fine on a new device and acceptable on an older device. If someone else does, please feel free to take my answer as a source and repost.

package pl.mkaras.utils;
import android.content.Context;
import android.support.design.widget.AppBarLayout;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.Toolbar;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;
public class ScrollViewBehaviorFix extends AppBarLayout.ScrollingViewBehavior {
public ScrollViewBehaviorFix() {
super();
}
public ScrollViewBehaviorFix(Context context, AttributeSet attrs) {
super(context, attrs);
}
public boolean onMeasureChild(CoordinatorLayout parent, View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec,
int heightUsed) {
if (child.getLayoutParams().height == -1) {
List<View> dependencies = parent.getDependencies(child);
if (dependencies.isEmpty()) {
return false;
}
final AppBarLayout appBar = findFirstAppBarLayout(dependencies);
if (appBar != null && ViewCompat.isLaidOut(appBar)) {
int availableHeight = View.MeasureSpec.getSize(parentHeightMeasureSpec);
if (availableHeight == 0) {
availableHeight = parent.getHeight();
}
final int height = availableHeight - appBar.getMeasuredHeight();
int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);
parent.onMeasureChild(child, parentWidthMeasureSpec, widthUsed, heightMeasureSpec, heightUsed);
int childContentHeight = getContentHeight(child);
if (childContentHeight <= height) {
updateToolbar(parent, appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed, false);
heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.EXACTLY);
parent.onMeasureChild(child, parentWidthMeasureSpec, widthUsed, heightMeasureSpec, heightUsed);
return true;
} else {
updateToolbar(parent, appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed, true);
return super.onMeasureChild(parent, child, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
}
}
}
return false;
}
private static int getContentHeight(View view) {
if (view instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup) view;
int contentHeight = 0;
for (int index = 0; index < viewGroup.getChildCount(); ++index) {
View child = viewGroup.getChildAt(index);
contentHeight += child.getMeasuredHeight();
}
return contentHeight;
} else {
return view.getMeasuredHeight();
}
}
private static AppBarLayout findFirstAppBarLayout(List<View> views) {
int i = 0;
for (int z = views.size(); i < z; ++i) {
View view = views.get(i);
if (view instanceof AppBarLayout) {
return (AppBarLayout) view;
}
}
throw new IllegalArgumentException("Missing AppBarLayout in CoordinatorLayout dependencies");
}
private void updateToolbar(CoordinatorLayout parent, AppBarLayout appBar, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec,
int heightUsed, boolean toggle) {
toggleToolbarScroll(appBar, toggle);
appBar.forceLayout();
parent.onMeasureChild(appBar, parentWidthMeasureSpec, widthUsed, parentHeightMeasureSpec, heightUsed);
}
private void toggleToolbarScroll(AppBarLayout appBar, boolean toggle) {
for (int index = 0; index < appBar.getChildCount(); ++index) {
View child = appBar.getChildAt(index);
if (child instanceof Toolbar) {
Toolbar toolbar = (Toolbar) child;
AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) toolbar.getLayoutParams();
int scrollFlags = params.getScrollFlags();
if (toggle) {
scrollFlags |= AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL;
} else {
scrollFlags &= ~AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL;
}
params.setScrollFlags(scrollFlags);
}
}
}
}
This behavior basically removes scroll flag SCROLL from AppBarLayout, when scrolling content in dependent view (RecyclerView, NestedScrollView) is less than view height, ie. when scrolling is not needed. It also overrides offsetting scrolling view, which is normally done by AppBarLayout.ScrollingViewBehavior. Works well when adding footer, ie. button, to scrolling view or in ViewPager, where content length may be different in each page.

I think creating a fixed header and footer could solver your problem. I would've wrote this in the comments but I don't have 50 rep. You could figure out how to do it here

I did something along the lines of ensuring I added
android:layout_gravity="end|bottom"
to the layout in XML that I wanted at the bottom of the CoordinatorLayout
and then set in code:
mRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#SuppressLint("NewApi")
#SuppressWarnings("deprecation")
#Override
public void onGlobalLayout() {
if (mFooterView != null) {
final int height = mFooterView.getHeight();
mRecyclerView.setPadding(0, 0, 0, height);
mRecyclerView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
}
});
Note: that the footer View/ViewGroup needs to be higher in the z-axis (listed below the RecyclerView in XML) to function properly

Surround your elements with a linearlayout, like that:
<android.support.design.widget.CoordinatorLayout >
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout>
<android.support.v7.widget.Toolbar />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_main" />
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>

Android CoordinatorLayout Bottom Layout Behaviour Example
activity_bottom.xml
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimaryDark"
app:layout_scrollFlags="scroll|enterAlways"
app:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar" />
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#C0C0C0"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<com.example.android.coordinatedeffort.widget.FooterBarLayout
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:layout_gravity="bottom">
<TextView
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#007432"
android:gravity="center"
android:text="Footer View"
android:textColor="#android:color/white"
android:textSize="25sp" />
</com.example.android.coordinatedeffort.widget.FooterBarLayout>
</android.support.design.widget.CoordinatorLayout>
FooterBarLayout.java
FooterBarBehavior.java

There is a library for your problem. Hope this will really help for you
Here is the library
And another problem you have mentioned fixed the footer. the below one is the relative layout so use the feature android:layout_alignParentBottom="true" on your footer.
Hope you i have solved the issue

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.