Add elevation/shadow on toolbar for pre-lollipop devices

For Android 5.0 and above : AppBarLayout automatically provides/gives shadow in the layout. You can also increase the elevation of the AppBarLayout by app:elevation="4dp".

For Pre-Lollipop : You can use the following link: https://github.com/vipulasri/Toolbar-Elevation-Pre-Lollipop

Note: Toolbar also supports elevation to it, using android:elevation="4dp"

New Update: In Appcompat v24.0.0, you can not set elevation to AppBarLayout using setElevation() and app:elevation as these are deprecated.

You have to use stateListAnimator property to set elevation now.

Note: set duration to 1ms in StateListAnimator in order to avoid delay in Elevation Drawing.

AppBarLayout elevation change is delayed on appCompat v24.0.0

appbar_always_elevated.xml in animator-v21 folder under res directory.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item>
    <objectAnimator android:propertyName="elevation"
                    android:valueTo="8dp" 
                    android:valueType="floatType"
                    android:duration="1"/>
</item>
</selector>

In AppbarLayout :

<android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:fitsSystemWindows="true"
        android:stateListAnimator="@animator/appbar_always_elevated"
        android:theme="@style/AppTheme.AppBarOverlay">

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

Try using the AppBarLayout inside the activity layout. Try:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <include
            layout="@layout/Toolbar" />
    </android.support.design.widget.AppBarLayout>

    <fragment
        class="OverAllField.XamarinAndroid.Fragments.Planning.PlanningFragment"
        android:id="@+id/PlanningFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

Toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/Toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?attr/actionBarSize"
    android:background="?attr/colorPrimary"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

use build file:

compile 'com.android.support:cardview-v7:23.1.1'

refer this link

to call in xml add:

app:cardElevation="8dp"
app:cardCornerRadius="8dp"
app:contentPadding="5dp"

I think the best solution is to put a gradient shadow view below the toolbar and manipulate with visibility depends on device sdk.

toolbar.xml

 <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout 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="wrap_content"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@android:color/white"
            android:fitsSystemWindows="true"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/centerTitleToolbarTextView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:gravity="center"
                android:maxLines="1"
                android:textColor="@color/color_toolbar"
                android:textSize="@dimen/titleToolbar" />

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

        <View
            android:id="@+id/shadow_view"
            android:layout_width="match_parent"
            android:visibility="gone"
            android:layout_height="4dp"
            android:background="@drawable/toolbar_shadow" />

    </LinearLayout>

toolbar_shadow.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:startColor="#c1c1c1"
        android:centerColor="#e6e6e6"
        android:endColor="#f1f1f1"
        android:angle="270" />
</shape>

MainActivity.class

if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        findViewById(R.id.shadow_view).setVisibility(View.VISIBLE);
      }

I have a CollapsingToolbarLayout with Toolbar and a Toolbar-like View that moves up and down, but lays above NestedScrollView, like in https://github.com/k0shk0sh/CoordinatorLayoutExample. I tried many variants. Sometimes a shadow scrolled above a screen with NestedScrollView, sometimes the Toolbar drew a solid shadow without transparency, sometimes the shadow was aliased. Anyway, this is my solution.

Say, you have a layout:

<android.support.design.widget.CoordinatorLayout>
    <android.support.design.widget.AppBarLayout>
         <android.support.design.widget.CollapsingToolbarLayout>
             <android.support.v7.widget.Toolbar>
                 <!-- Toolbar views if needed -->
             </android.support.v7.widget.Toolbar>
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

    <!-- Footer Toolbar views if needed -->

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

        <LinearLayout>
            <!-- Views -->
        </LinearLayout>

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

    <!-- Add this view. It draws a shadow and aligns top of NestedScrollView -->
    <!-- Set visibility to gone or visible -->
    <View
        android:id="@+id/scroll_shadow"
        android:layout_width="match_parent"
        android:layout_height="4dp"
        android:background="@drawable/shadow"
        android:visibility="gone"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

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

Add a shadow (drawable/shadow.xml):

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:angle="90"
        android:endColor="#ffcccccc"
        android:startColor="#00cccccc" />
</shape>

Add this method. Here scrollShadow is a view named "scroll_shadow":

private void setShadowVisibility(int visibility) {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        scrollShadow.setVisibility(visibility);
    }
}

Manipulate it as you wish. It will show a gradient on pre-Lollipop devices and shows a normal shadow for Android 5.0+.