Develop Reference

No resource found that matches the given name: attr 'android:elevation'

I'm trying to rebuild an Android application on VS and Xamarin
but I get this error
No resource found that matches the given name: attr
'android:elevation'.
this is the attribute:
<item name="android:elevation">#dimen/design_bottom_sheet_modal_elevation</item>
I use these values for compiling:
the error comes from the file values.xml, but sometimes the same error happens with different attributes in files; values-23.xml or 22..etc

Change the compilation version to Android 5.0 or above.
elevation attribute was introduced in 5.0.
So Kit-kat build tools will fail.

Elevation is only for Android 5.x+ so you must change compilation to use 5.0 or above.
your /Resources/values/style.xml should look more or less like:
<?xml version="1.0" encoding="utf-8" ?>
<resources>
<style name="MyTheme" parent="MyTheme.Base">
</style>
<style name="MyTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">
<!--If you are using revision 22.1 please use just windowNoTitle. Without android:-->
<item name="windowNoTitle">true</item>
<!--We will be using the toolbar so no need to show ActionBar-->
<item name="windowActionBar">false</item>
<!-- Set theme colors from http://www.google.com/design/spec/style/color.html#color-color-palette-->
<!-- colorPrimary is used for the default action bar background -->
<item name="colorPrimary">#00FFAA</item>
<!-- colorPrimaryDark is used for the status bar -->
<item name="colorPrimaryDark">#004D40</item>
<!-- colorAccent is used as the default value for colorControlActivated
which is used to tint widgets -->
<item name="colorAccent">#color/accent</item>
<!-- You can also set colorControlNormal, colorControlActivated
colorControlHighlight and colorSwitchThumbNormal.
<item name="colorControlNormal">#00897B</item>
<item name="colorControlActivated">#1DE9B6</item>-->
<item name="windowActionModeOverlay">true</item>
</style>
</resources>
Also check your style.xml in your /Resources/values folder and make sure you set styles for API level v21+ look like: /Resources/values-v21/style.xml
<?xml version="1.0" encoding="utf-8" ?>
<resources>
<!--
Base application theme for API 21+. This theme replaces
MyTheme from resources/values/styles.xml on API 21+ devices.
-->
<style name="MyTheme" parent="MyTheme.Base">
<item name="android:windowContentTransitions">true</item>
<item name="android:windowAllowEnterTransitionOverlap">true</item>
<item name="android:windowAllowReturnTransitionOverlap">true</item>
<item name="android:windowSharedElementEnterTransition">#android:transition/move</item>
<item name="android:windowSharedElementExitTransition">#android:transition/move</item>
</style>
</resources>

Set property as AndroidResource in BuildAction for all style.xml and image files. Keep in mind all the files must be in Resources folder within .Droid project.

Remove action bar shadow

I want to remove the shadow that appears below the appcompat action bar so that the background of the action bar is completely transparent.
This is my theme and action bar style:
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light">
<!-- Customize your theme here. -->
<item name="colorPrimary">#color/colorPrimary</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorAccent">#color/colorAccent</item>
<item name="android:actionBarStyle">#style/TransparentActionBar</item>
<item name="android:windowActionBarOverlay">true</item>
<!-- Support library compatibility -->
<item name="actionBarStyle">#style/TransparentActionBar</item>
<item name="windowActionBarOverlay">true</item>
</style>
<!-- Transparent Action Bar Style -->
<style name="TransparentActionBar"
parent="Widget.AppCompat.Light.ActionBar.Solid.Inverse">
<item name="android:background">#android:color/transparent</item>
<!-- Support library compatibility -->
<item name="background">#android:color/transparent</item>
<item name="elevation">0dp</item>
</style>
My minimum API level is 16
I've tried several solutions for this including:
Setting elevation to 0dp only works for Lollipop devices.
I get a "resource not found" error if I try to use windowContentOverlay
Setting the background of the root view to a color like white or transparent doesn't work
I've been trying to get this to work on 4.4.4 to no avail. Is it not possible below API level 21?
EDIT:
it turns out that the windowContentOverlay only works with the android prefix:
<item name="android:windowContentOverlay">#null<item/>
Trying to also define it without the prefix results in the resource not found error (this error points to the one with the prefix for whatever reason). I honestly don't understand why this occurs. I can only assume appcompat doesn't support the windowContentOverlay attribute.

Set windowContentOverlay to a drawable that will be drawn under the action bar. If you don't want a shadow set it to null, like so:
<item name="android:windowContentOverlay">#null</item>
and
<item name="windowContentOverlay">#null</item>
This works API level 16 and up.

The different between <item name="title"> and <item name="android:title">

I make ActionBar in app.I change ActionBar style.There are some questions.
I want to change the title in the ActionBar.
So I write the follow code.
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="android:actionBarStyle">#style/ActionBar</item>
<item name="actionBarStyle">#style/ActionBar</item>
<item name="actionOverflowButtonStyle">#style/overflowButton</item>
</style>
<!--ActionBar-->
<style name="ActionBar" parent="#style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
<item name="android:background">#color/bg</item>
<item name="background">#color/bg</item>
<item name="android:title">#string/test</item>
<item name="title">#string/test</item>
</style>
<style name="overflowButton">
<item name="android:src">#mipmap/ic_add_black_48dp</item>
<item name="android:showAsAction"></item>
</style>
</resources>
when I only write <item name="android:title">#string/test</item> ,it doesn't work,but write <item name="title">#string/test</item> it work.
I have try to solve in Android Developer,but fail.Please help me.

<item name="title">#string/test</item>
this tag works on supporting library, and
<item name="android:title">#string/test</item>
this one works on your android. For more detail please have a look on here
I hope you understand, If not please let me know.

Note: If you are using the Support Library APIs for the action bar, then you must use (or override) the Theme.AppCompat family of styles (rather than the Theme.Holo family, available in API level 11 and higher). In doing so, each style property that you declare must be declared twice: once using the platform's style properties (the android: properties) and once using the style properties included in the Support Library (the appcompat.R.attr properties—the context for these properties is actually your app).

How to change action bar size

I would like to change the action bar size. I have tried the following coding.
<style name="MyTheme" parent="#android:style/Theme.Holo.Light">
<item name="android:actionBarStyle">#style/CustomActionBar</item>
</style>
<style name="CustomActionBar" parent="#android:style/Widget.Holo.Light.ActionBar">
<!-- <item name="android:background">#drawable/action_bar_style</item> -->
<item name="android:actionBarSize">15dp</item>
<item name="android:background">#drawable/header_bar</item>
</style>
But the action bar size didn't change. Is there another way? I am using api level 11.
Thanks.

Use height attribute, actionBarSize if for something else.
<item name="android:height">#dimen/bar_height</item>
Explanantion:
From source code of ActionBar:
mContentHeight = a.getLayoutDimension(R.styleable.ActionBar_height, 0);
We can see that R.styleable.ActionBar_height is being used for height. Stylable property names are generated as component_attribute (If you have ever used a custom stylable view, you'd have notice this). Hence, Actionbar is the name of component and height is the name of the attribute to use. Since this is a system attribute, hence defined under android namespace.
Update Dec-2014:
AppCompat library is now provided to extend support for latest ActionBar (or Toolbar) and theme support to old android versions. Below is an example of such an application theme /res/values/styles.xml:
<resources>
<!-- Application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light">
<!-- Main theme colors -->
<!-- your app branding color for the app bar -->
<item name="colorPrimary">#color/primary</item>
<!-- darker variant for the status bar and contextual app bars -->
<item name="colorPrimaryDark">#color/primary_dark</item>
<!-- theme UI controls like checkboxes and text fields -->
<!-- native widgets will now be "tinted" with accent color -->
<item name="colorAccent">#color/accent</item>
<!--Action bar style-->
<item name="android:actionBarStyle">#style/AppTheme.ActionBar</item>
<item name="actionBarStyle">#style/AppTheme.ActionBar</item>
</style>
<style name="AppTheme.ActionBar" parent="Widget.AppCompat.Light.ActionBar">
<item name="android:titleTextStyle">#style/AppTheme.ActionBar.TitleText</item>
<item name="titleTextStyle">#style/AppTheme.ActionBar.TitleText</item>
<item name="android:height">#dimen/bar_height</item>
<item name="height">#dimen/bar_height</item>
</style>
<style name="AppTheme.ActionBar.TitleText" parent="TextAppearance.AppCompat.Widget.ActionBar.Title">
<item name="android:textSize">#dimen/bar_text_size</item>
<item name="android:textColor">#color/bar_text_color</item>
</style>
</resources>
This style can now be set as app theme by using android:theme="#style/AppTheme" in <application> tag of the AndroidManifest.xml.
Note the use of duplicate entries
<item name="android:actionBarStyle">
<item name="actionBarStyle">
The ones without android namespace are there for supporting both compatibility library and native attributes.Some of these attributes didn't exist under android namespace on older versions and belong to support library.
In some other places, you'll need to use app namespace (xmlns:app="http://schemas.android.com/apk/res-auto"), for example app:showAsAction="always" in menu xml files.
Update Apr 2015
AppCompat Library v22 is also available. Read through the article to know what's new.

Simply put actionBarSize item under MyTheme style, like this:
<style name="MyTheme" parent="#android:style/Theme.Holo.Light">
<item name="android:actionBarSize">15dp</item>
<item name="actionBarSize">15dp</item>
...
</style>
Explanation:
In R.styleable we see that R.styleable.Theme_actionBarSize is a styleable attribute defined at Theme level.
Also, from source code res/values/styles.xml we see how actionBarSize is used to set height:
<style name="Widget.ActionBar">
...
<item name="android:height">?android:attr/actionBarSize</item>

Add this to the custom theme style XML that you are referencing from your manifest file:
<item name="android:windowTitleSize">58dip</item>
For instance if your manifest file looks something like this:
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
**android:theme="#style/AppTheme"** >
Your theme style should be -at least- like this:
<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
<item name="android:windowTitleSize">54dip</item>
</style>

S.D.'s solution does not work for me.
I used AppCompat v-21 library in my case.
And I just add
android:layout_height="#dimen/actionBarSize"
android:minHeight="#dimen/actionBarSize"
to my layout file and it works.

Make sure to add S.D.'s code to styles.xml and then add
android:theme="#style/thin_ab"
to the <application> element in the main manifest. (I'm a noob and it took me about 2 hours to find that out.)

ActionBarDisappearing on Android 4.0+

I am currently writing an application for devices on 2.3 - 4.2+ and am having some weird, and unexpected issues. It was working fine until and displaying on all devices before I attempted to theme it. Even with a simple style simply extending the action bar sherlock theme, there appears to be no action bar showing.
The setup for the styles.
<style name="FrameworkRoot.Theme" parent="Theme.Sherlock.Light.DarkActionBar">
<!-- API 11+ (compatibility) -->
<item name="buttonBarStyle">#style/Compat.ButtonBar</item>
<item name="buttonBarButtonStyle">#style/Compat.ButtonBarButton</item>
<item name="indeterminateProgressStyle">#style/Compat.IndeterminateProgress</item>
<!-- API 14+ (compatibility) -->
<item name="listPreferredItemPaddingLeft">#dimen/compat_list_preferred_item_padding_left</item>
<item name="listPreferredItemPaddingRight">#dimen/compat_list_preferred_item_padding_right</item>
<item name="listPreferredItemHeightSmall">#dimen/compat_list_preferred_item_height_small</item>
</style>
<style name="Theme.Base" parent="FrameworkRoot.Theme">
<item name="textHeaderMaxLines">#integer/text_header_max_lines</item>
<item name="trackAbstractMaxLines">#integer/track_abstract_max_lines</item>
<item name="activatableItemBackground">#drawable/activatable_item_background</item>
</style>
<!-- Base themes for the app -->
<style name="Theme.TestApp" parent="Theme.Base">
<item name="actionBarStyle">#style/Widget.TestApp.ActionBar</item>
<item name="android:actionBarStyle">#style/Widget.TestApp.ActionBar</item>
</style>
<!-- Base Action Bar Style -->
<style name="Widget.TestApp.ActionBar" parent="Theme.Sherlock.Light.DarkActionBar">
</style>
If I remove the:
<item name="android:actionBarStyle">#style/Widget.TestApp.ActionBar</item>
So that the action bar itself it not getting styled in 3.0+, I can't style the bar.
What would be the best way to set this up? AndroidManifest.xml is pointing the app's style at "Theme.TestApp".
My end goal is to have a custom background on the action bar, as well as custom tab selector colors and fonts. What would be the best way to go about this, as my current method isn't working well.

You have to set an attribute for ActionBarSherlock and the native ActionBar. So replace this for example:
<style name="Theme.Base" parent="FrameworkRoot.Theme">
<item name="textHeaderMaxLines">#integer/text_header_max_lines</item>
<item name="trackAbstractMaxLines">#integer/track_abstract_max_lines</item>
<item name="activatableItemBackground">#drawable/activatable_item_background</item>
</style>
With this:
<style name="Theme.Base" parent="FrameworkRoot.Theme">
<item name="textHeaderMaxLines">#integer/text_header_max_lines</item>
<item name="trackAbstractMaxLines">#integer/track_abstract_max_lines</item>
<item name="activatableItemBackground">#drawable/activatable_item_background</item>
<item name="android:textHeaderMaxLines">#integer/text_header_max_lines</item>
<item name="android:trackAbstractMaxLines">#integer/track_abstract_max_lines</item>
<item name="android:activatableItemBackground">#drawable/activatable_item_background</item>
</style>
The attributes with the 'android' prefix point to the internal resources for the native ActionBar, the attributes without the 'android' in front point to the resources of the ActionBarSherlock.