WebView with a collapsible Toolbar? (material design)

Question

I'm developing an Android app with an Activity and two kind of fragments.

Type 1: a fragment with a collapsible toolbar and a RecyclerView as content. (It works). Layout:

<android.support.design.widget.CoordinatorLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginEnd="64dp"
            app:expandedTitleMarginStart="48dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <ImageView
                android:id="@+id/header"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@drawable/indicaciones"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax" />


            <android.support.v7.widget.Toolbar
                android:id="@+id/anim_toolbar"
                android:layout_width="match_parent"
                android:layout_height="100dp"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

            </android.support.v7.widget.Toolbar>

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/scrollableview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:clickable="true"
        android:src="@android:drawable/ic_menu_add"
        android:visibility="gone"
        app:layout_anchor="@+id/appbar"
        app:layout_anchorGravity="bottom|right|end" />


</android.support.design.widget.CoordinatorLayout>

Type 2: a fragment with a collapsible toolbar and a WebView as content. (Here is the problem). I've tried changing RecyclerView by "WebView" and it looks like this:

<android.support.design.widget.CoordinatorLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginEnd="64dp"
            app:expandedTitleMarginStart="48dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <ImageView
                android:id="@+id/header"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@drawable/indicaciones"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax" />


            <android.support.v7.widget.Toolbar
                android:id="@+id/anim_toolbar"
                android:layout_width="match_parent"
                android:layout_height="100dp"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

            </android.support.v7.widget.Toolbar>

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <WebView
        android:id="@+id/scrollableview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:clickable="true"
        android:src="@android:drawable/ic_menu_add"
        android:visibility="gone"
        app:layout_anchor="@+id/appbar"
        app:layout_anchorGravity="bottom|right|end" />


</android.support.design.widget.CoordinatorLayout>

The problem is that the WebView doesn't appear. Any suggestions? Any idea to achieve this? Am I doing it ok?

Thanks in advance.

EDIT:

I load the webView this way:

String template = ... (a xml string, well formed).
webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setBuiltInZoomControls(true);
        webView.getSettings().setDisplayZoomControls(false);
        webView.loadDataWithBaseURL("file:///android_asset/", template, "text/html", "UTF-8", "");
        webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        webView.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
        webView.getSettings().setSupportZoom(true);
        webView.getSettings().setRenderPriority(WebSettings.RenderPriority.HIGH);

I have also tried this:

 WebSettings ws = webView.getSettings();
    ws.setJavaScriptEnabled(true);
    webView.loadUrl("http://www.google.com");

    webView.setWebViewClient(new WebViewClient() {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }
    });

Answer 1

Put your Webview into NestedScrollView and set android:isScrollContainer:false

So it should be

<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <WebView
        android:id="@+id/scrollableview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white"
        android:isScrollContainer="false"/>

</android.support.v4.widget.NestedScrollView>

Instead of your WebView

Answer 2

You can listen to the scroll event to make a collapsing effect.

Layout

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.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">

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/appBarLayout"
    android:layout_width="match_parent"
    android:layout_height="146dp">

    <com.google.android.material.appbar.CollapsingToolbarLayout
        android:id="@+id/collapsingToolbarLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:contentScrim="@color/primary"
        app:expandedTitleGravity="bottom"
        app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:layout_collapseMode="pin" />

    </com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>

<WebView
    android:id="@+id/webview"
    android:layout_width="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:layout_height="match_parent"/>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Code

webview.setOnScrollChangeListener(new View.OnScrollChangeListener() {
  @Override
  public void onScrollChange(View view, int i, int i1, int i2, int i3) {
    // i1 last Y, i3 previous Y
    // Do you stuff here. A simple example: (not performant)
    AppBarLayout appBarLayout = 
    CollapsingToolbarActivity.this.findViewById(R.id.appBarLayout);
    appBarLayout.setExpanded(i1 < i3, true);
  }
});