Develop Reference

Toolbar xml shadow (elevation) can get working only on Android 21+

So I've added Navigation Drawer and because of it I have to use Toolbar in my layout xml file (instead of using theme with action bar Theme.AppCompat.Light.DarkActionBar, and now it's Theme.AppCompat.Light.NoActionBar)
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:theme="#style/ThemeOverlay.AppCompat.ActionBar"/>
</com.google.android.material.appbar.AppBarLayout>
I found this answer to add shadow below toolbar (AppBarLayout) https://stackoverflow.com/a/31026359/9766649
But it only works for Android 21+
With Theme.AppCompat.Light.DarkActionBar shadow is working for older Android
So the only solution is to use custom shadow like https://stackoverflow.com/a/26904102/9766649 ?

I decided to use different implementation for older and newer Android
For Android 21+ (layout-v21/activity_main.xml):
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android">
<include layout="#layout/toolbar_view"/>
</com.google.android.material.appbar.AppBarLayout>
<include layout="#layout/content"/>
</LinearLayout>
For older Android (layout/activity_main.xml):
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include layout="#layout/toolbar_view"/>
<FrameLayout android:layout_width="match_parent"
android:layout_height="match_parent">
<include layout="#layout/content"/>
<View android:layout_width="match_parent"
android:layout_height="5dp"
android:background="#drawable/drop_shadow"/>
</FrameLayout>
</LinearLayout>
toolbar_view.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:theme="#style/ThemeOverlay.AppTheme.ActionBar"
xmlns:android="http://schemas.android.com/apk/res/android"/>
drawable/drop_shadow.xml (to add elevation below toolbar for older Android):
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient android:startColor="#android:color/transparent"
android:endColor="#88666666"
android:angle="90"/>
</shape>

How to make Toolbar in AppBarLayout to have transparent background

I need to make transparent toolbar with buttons, but AppBarLayout adds white background to toolbar. Is there any way I can make toolbar which is in AppBarLayout to be transparent.
<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:background="?attr/activityBackgroundColor"
>
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
/>
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
app:elevation="0dp"
app:theme="#style/AppTheme.Overlay"
>
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#android:color/transparent"
app:layout_collapseMode="pin"
app:layout_scrollFlags="scroll|enterAlways"
app:theme="#style/Toolbar.Translucent"
/>
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>

Most of the times we want the toolbar to be translucent because we want to show content behind it. The problem is that the colors of the content behind the toolbar can collide with the color of the toolbar elements/text (up/back arrow for example).
For that reason you'll see in a lot of implementations that the toolbar is actually not transparent but translucent with a gradient.
You can obtain this with the next code
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#drawable/background_toolbar_translucent" />
background_toolbar_translucent.xml
<?xml version="1.0" encoding="utf-8"?>
<shape
xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
android:angle="270"
android:endColor="#android:color/transparent"
android:startColor="#color/black_alpha_40"/>
colors.xml
<color name="black_alpha_40">#66000000</color>
You can play with different values on the gradient, what I've found is that for white elements, the black 40% works fine.
Another thing that you might want to do is to hide the title of the toolbar.
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
And show the up affordance...
getSupportActionBar().setDisplayShowTitleEnabled(false);

Set logo as toolbar background in Android

I am attempting to set a logo as background in an Android toolbar. I've tried to put the image as a layer directly in the toolbar but this results in the logo not being centered. Here is the code I've got right now:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/toolbar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minHeight="?attr/actionBarSize"
android:background="#drawable/Toolbar_background"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
</android.support.v7.widget.Toolbar>
And for the drawable Toolbar_background:
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize">
<item>
<shape android:shape="rectangle">
<solid android:color="?attr/colorPrimary" />
</shape>
</item>
<item>
<bitmap
android:contentDescription="Unleashed logo"
android:src="#drawable/unleashed"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="10dp"
android:paddingBottom="10dp" />
</item>
</layer-list>
This works but the logo is stretched in width and no padding is aplied, the bitmap takes up all spaces it can get.
https://www.imgdumper.nl/uploads9/5a796ede6c77c/5a796ede6bd4d-Capture.PNG

You can create custom toolbar.
Check below code.
toolbar_bg_image.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?android:attr/actionBarSize"
android:background="#color/colorAccent"
app:contentInsetEnd="0dp"
app:contentInsetLeft="0dp"
app:contentInsetRight="0dp"
app:contentInsetStart="0dp"
app:layout_collapseMode="pin"
app:popupTheme="#style/toolbarTheme">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/_4sdp"
android:paddingRight="#dimen/_4sdp"
android:paddingStart="#dimen/_4sdp"
android:paddingEnd="#dimen/_4sdp"
android:layout_marginLeft="#dimen/_20sdp"
android:layout_marginRight="#dimen/_20sdp"
android:scaleType="fitXY"
app:srcCompat="#drawable/unlashed"/>
</android.support.v7.widget.Toolbar>
</layout>
I suggest you to take your image without background and set background color as per your requirement in android:background="#color/colorAccent" property of toolbar.
You can also set margin and padding in ImageView as per your requirement.
Now you can include this toolbar in your layout file as below.
fragment_or_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:orientation="vertical">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar_bg_image" />
</LinearLayout>
</layout>

You can try setting logo as below:
<Toolbar
android:layout_width="match_parent"
android:layout_height="?android:attr/actionBarSize"
android:id="#+id/atc_toolbar"
android:background="?android:attr/colorPrimaryDark"
android:elevation="4dp"
android:navigationIcon="#android:drawable/ic_menu_compass"
android:logo="#android:drawable/ic_menu_view"
android:title="My application">
</Toolbar>

CollapsingToolbarLayout without shadow in expanded state

CollapsingToolbarLayout from appcompat shows shadow in collapsed state, but when expanded (or expanding in process) shadow disappear
My example code https://github.com/NaikSoftware/CollapsingToolbarWithImageAndTabs/tree/master/app
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"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="ua.naiksoftware.hidetabs.MainActivity">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.design.widget.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="#dimen/toolbar_plus_tabs"
app:contentScrim="#android:color/transparent"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap|enterAlways"
app:titleEnabled="false"
app:toolbarId="#+id/toolbar_wrapper">
<ImageView
android:id="#+id/appbar_background"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:src="#drawable/header_back"
app:layout_collapseMode="parallax"/>
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#android:color/transparent"
app:popupTheme="#style/AppTheme.PopupOverlay" />
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_wrapper"
android:layout_width="match_parent"
android:layout_gravity="bottom"
android:background="#android:color/transparent"
android:layout_height="wrap_content"
android:minHeight="#dimen/tab_layout_height">
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
app:tabGravity="fill"
app:tabIndicatorColor="#android:color/white"
app:tabMode="scrollable"
app:tabSelectedTextColor="#android:color/white" />
</android.support.v7.widget.Toolbar>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<android.support.design.widget.FloatingActionButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/ic_add_black_24dp"
android:layout_margin="#dimen/fab_margin"
android:tint="#android:color/white"
android:layout_gravity="bottom|end"
app:elevation="#dimen/fab_elevation"
app:layout_behavior="ua.naiksoftware.hidetabs.FabSlidingBehavior"/>
</android.support.design.widget.CoordinatorLayout>
Collapsed
Expanded

I had the same issue and found a solution:
First you have to update to the latest Support Library (I use 24.1.0)
Then apply the stateListAnimator to your AppBarLayout:
example:
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="320dp"
android:stateListAnimator="#drawable/appbar_always_elevated"
android:fitsSystemWindows="true">
and use this xml as animator:
<?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>

You can find official stateListAnimator for AppBarLayout here
1. Put this appbar_elevation.xml into resources directory named animator-v21
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
tools:ignore="PrivateResource">
<item>
<objectAnimator
android:propertyName="elevation"
android:valueTo="#dimen/design_appbar_elevation"
android:valueType="floatType" />
</item>
</selector>
2. On AppBarLayout set android:stateListAnimator="#animator/appbar_elevation"

Just use
app:liftOnScroll="false"
on the AppBarLayout

Fading android.support.v7.widget.Toolbar

I want to create a profile activity which toolbar should look somehow like this:
So far I have this:
Also I don't understand how to get rid of this shadow or overlay effect, maybe this would already solve my problem.
activity_activity_profil.xml
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.appmac.ron.app_newsfeed.ActivityProfil">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#drawable/toolbar_color"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_activity_profil" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
toolbar_color.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient
android:angle="90"
android:centerColor="#7b7b7b"
android:endColor="#2b2b2b"
android:startColor="#ffffff"
android:type="linear" />
</shape>
UPDATE:
The Shadow is gone, now i would like to make my Toolbar transparent, like this:
I have this right now:
If more code is needed just tell me and I'll update it.
Thankful for any help!

Set the elevation to 0dp on your AppBarLayout:
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:elevation="0dp"
android:theme="#style/AppTheme.AppBarOverlay">
You might want to move the background to the AppBarLayout as well.