Develop Reference

Changing background colour of activities themed using the AppCompat themes in older Android versions

I am using the following theme for my application:
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat">
<!-- Customize your theme here. -->
<item name="colorPrimary">#color/colorPrimary</item>
<item name="colorPrimaryDark">#color/colorPrimaryDark</item>
<item name="colorAccent">#color/colorAccent</item>
</style>
I would like to change the background colour. In order to do so, according to the documentation I can add the following to the theme definition:
<item name="windowBackground">#color/windowBackground</item>
Unfortunately, however, this only compiles correctly if (as suggested in the answer at No resource found that matches the given name: attr 'windowBackground') I restrict it to being applied to Android versions with API 21 or higher.
How I can I make this work on earlier versions of Android? I would ideally like to specify a background colour for Android versions down to API 16, which is my current minimum.

That's true as you said that windowBackground so you will just need to replace it with android:windowBackground that is for API 14 and higher

You need to add
<item name="android:windowBackground">#color/window_background</item>
to ../values-v21/styles.xml

// Your Problem is that You are use Theme.Appcompat then extends ActionBarActivity
if you use AppcompatActivity then use
<style name="MyTheme" parent="Theme.AppCompat.Light">
<item name="android:windowBackground">#color/colorAccent</item>
</style>

Changing themes and styles based on the Android version on build

I know I can add different XMLs for different API levels, for example having different styles for values-v21 and values-v19. What I'm trying to understand is how the build system actually works with those different values? So for example if I have the bulk of my styles common across all APIs and one item of one style changes between 21 and the rest, do I:
1) Copy the whole styles.xml into v21 and change the one value I need to change
2) Only add that one style that changed to styles.xml under v21
3) Only add that one item of that one style that changed under 21
It's confusing and I couldn't find any documentation how the built process handles merging styles.

Rules are quite clear:
While running Android selects the best-matching style
If selected style is a child style, Android merges its items with parent best-matching style
If you provide your mutable item via a reference, just define its value to match selected api version.
<style name="SomeStyle">
<item name="someColor">#color/some_color</item>
</style>
You can have some_color.xml in color-v21 folder for API 21 and a common version of this file in a color folder for all other api levels.
Example:
You want to have the following style for non-v21 API
<style name="FinalStyle">
<item name="commonText">It\'s a common text</item>
<item name="specificDrawable">#drawable/icon</item>
<item name="specificColor">#color/primary_color</item>
<item name="specificText">non-v21</item>
</style>
And the following style for v21 API
<style name="FinalStyle">
<item name="commonText">It\'s a common text</item>
<item name="specificDrawable">#drawable/icon</item>
<item name="specificColor">#color/secondary_color</item>
<item name="specificText">v21</item>
</style>
Specific-parameters differ between v21/non-v21 API, common parameters are common.
How to do it?
res/values/styles.xml
<style name="BaseStyle">
<item name="commonText">It\'s a common text</item>
<item name="specificDrawable">#drawable/icon</item>
</style>
<style name="FinalStyle" parent="BaseStyle">
<item name="specificColor">#color/primary_color</item>
<item name="specificText">non-v21</item>
</style>
res/values-v21/styles.xml
<style name="FinalStyle" parent="BaseStyle">
<item name="specificColor">#color/secondary_color</item>
<item name="specificText">v21</item>
</style>
res/drawable/icon.png
Common icon
res/drawable-v21/icon.png
v21 icon
When Android searches FinalStyle for v21, it selects FinalStyle definition from res/values-v21 as best-matching style, and merges with BaseStyle. In this example there is also another best-matching resource search, when Android searches #drawable/icon.

This is for anyone who comes across this and is still just as confused as I was, even after a lot of reading and trial & error. Hopefully this helps.
The folder structure is like #Dmitry stated.
res/values/styles.xml
<?xml version="1.0" encoding="utf-8"?>
<resources xmlns:tools="http://schemas.android.com/tools">
<style name="AppBase" parent="Theme.MaterialComponents.NoActionBar">
<!-- simple: overrides colorPrimary in parent theme -->
<item name="colorPrimary">#color/brand_blue</item>
<item name="colorSecondary">#color/brand_grey</item>
<!-- sets the attributes in materialButtonStyle with style: myMaterialButton -->
<!-- the materialButtonStyle attribute is what actually changes the button settings -->
<item name="materialButtonStyle">#style/myMaterialButton</item>
</style>
<!-- this style consists of common 'attributes' among all API versions -->
<!-- you can choose to add a parent to inherit an additional style -->
<!-- unlike the materialButtonStyle attribute, this parent is not necessary to change the button settings -->
<style name="myMaterialButton" parent="Widget.MaterialComponents.Button">
<item name="cornerRadius">60dp</item>
<item name="android:paddingVertical" tools:targetApi="26">20dp</item>
</style>
<!-- this will add on and override AppBase and should include any changes that differ from other API versions -->
<style name="AppBaseChanges" parent="AppBase">
<!-- to inherit myMaterialButton, you don't have to include it in here, since it's in AppBase -->
<!-- however, if you want to extend myMaterialButton, create a new style as its child -->
<item name="materialButtonStyle">#style/myMaterialButtonAPI_All</item>
</style>
<!-- make sure the parent is myMaterialButton to inherit/override its settings -->
<!-- this will be picked for all APIs lower than other styles like this -->
<style name="myMaterialButtonAPI_All" parent="myMaterialButton">
<item name="backgroundTint">?attr/colorPrimary</item>
</style>
</resources>
res/values-v2/styles.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- restate the same declaration as the other xml file-->
<style name="AppBaseChanges" parent="AppBase">
<!-- use a different name (...API_2) for the overriding style -->
<item name="materialButtonStyle">#style/myMaterialButtonAPI_2</item>
</style>
<style name="myMaterialButtonAPI_2" parent="myMaterialButton">
<item name="backgroundTint">?attr/colorSecondary</item>
</style>
</resources>
Set the manifest theme to AppBaseChanges. The app will pick only one AppBaseChanges style to apply changes, so be sure to carefully override the right styles to ensure you are inheriting from lower level versions.
For some reason, AndroidStudio doesn't do a good job at all previewing themes, so before you think it's not working, relaunch the app to see the changes. There are also situations where I have no idea why it wasn't updating the setting and couldn't find where it was overriding the theme. In those cases you can dig further, or avoid the hassle and just apply the relevant style directly to the view.
Here's the order of precedence for the sample themes described above. The higher the style, the higher precedence it has and will override the lower style.
either myMaterialButtonAPI_All or myMaterialButtonAPI_2
AppBaseChanges (only one is chosen)
myMaterialButton
Widget.MaterialComponents.Button
AppBase
Theme.MaterialComponents.NoActionBar

You may maintain only one styles.xml(default) file for all the device version.
Checkout my answer to How to remove repeating of similar styles in v19/styles.xml and v21/styles.xml files
https://stackoverflow.com/a/53445541/5745574

Android actionbar style ignored by later devices, using appcompat v7

I am using the Action Bar support library (appcompat v7), my app is set to a minimum api of 7, and a target of 21.
I have two styles files, a base one, and one targeted at devices api 11+.
When running the app on a device running KitKat, it seems that android:actionBarStyle is ignored, leaving the action bar styled as default (#style/Widget.AppCompat.ActionBar.Solid), instead of applying the given background.
But if I remove my v11 styles/comment them out, KitKat listens to the actionBarStyle attribute set in the base styles.xml file and sets my custom background without any problems.
So my question, where am I going wrong with the v11 styles?
From what I understand, according to the android docs, you are supposed to supply the additional styles for devices running 11+ using the android: prefix, but this just doesn't seem to be working for me.
Stripped down, this is my /res/values/styles.xml file:
<style name="My.Theme" parent="#style/Theme.AppCompat">
<item name="actionBarStyle">#style/ActionBar.Solid</item>
</style>
<style name="ActionBar.Solid" parent="#style/Widget.AppCompat.ActionBar.Solid">
<item name="background">#drawable/ab_solid_</item>
</style>
and this is my /res/values-v11/styles.xml file:
<style name="My.Theme" parent="#style/Theme.AppCompat">
<item name="android:actionBarStyle">#style/ActionBar.Solid</item>
</style>
<style name="ActionBar.Solid" parent="#style/Widget.AppCompat.ActionBar.Solid">
<item name="android:background">#drawable/ab_solid_</item>
</style>
as you can see, the only difference between the two is the use of the android: prefix.

According to the official doc, with the new AppCompat-v21, you can remove all of values-v14+ Action Bar styles and use only one theme declaration, in values:
<style name="Theme.MyTheme" parent="Theme.AppCompat.Light">
<!-- Set AppCompat’s actionBarStyle -->
<item name="actionBarStyle">#style/MyActionBarStyle</item>
</style>

Android: defining action bar style for a device running KitKat

I am defining action bar styles for an Android device running 4.4.2. I've tested the styles on a device running 4.3 and they work prefectly. The phone running KitKat however refuses to apply any of the rules defined by the style. I've defined the same theme in all three folders: values, values-11 and values-14.
<style name="AppTheme" parent="#style/Theme.AppCompat.Light">
<!-- Setting values in the android namespace affects API levels 14+ -->
<item name="android:actionBarStyle">#style/MyStyledActionBar</item>
</style>
<style name="MyStyledActionBar" parent="#style/Widget.AppCompat.Light.ActionBar">
<!-- Setting values in the android namespace affects API levels 14+ -->
<item name="android:background">#drawable/oc_actionbar_background</item>
<item name="android:titleTextStyle">#style/MyActionBarTitleText</item>
<item name="android:actionMenuTextAppearance">#style/MyActionBarMenuText</item>
<item name="android:actionMenuTextColor">#style/MyActionBarMenuText</item>
<item name="android:actionOverflowButtonStyle">#style/MyActionButtonOverFlow</item>
<item name="android:displayOptions">showHome</item>
</style>
<style name="MyActionBarTitleText" parent="#style/TextAppearance.AppCompat.Widget.ActionBar.Title">
<item name="android:textColor">#696969</item>
</style>
<style name="MyActionBarMenuText" parent="#style/TextAppearance.AppCompat.Widget.ActionBar.Menu">
<item name="android:textColor">#696969</item>
</style>
<style name="MyActionButtonOverFlow" parent="#style/Widget.AppCompat.Light.Base.ActionButton.Overflow">
<item name="android:src">#drawable/ic_action_search</item>
</style>
I've also added
android:theme="#style/AppTheme"
to the manifest application tag. But the styles are still not applied. I have however managed to change the action bar properties at runtime (changing the color), but that's not a desirable way of handling such problems.
If anyone could advise me on the matter, I would be most grateful.

To prevent these kind of issues, I like to use the following tool to generate the style for me: http://jgilfelt.github.io/android-actionbarstylegenerator/
Easy to use tool that generates the style just like I want it. Might help you too, since you avoid these issues. Just paste this in your project, and you're done.
Other tools can be found here: http://romannurik.github.io/AndroidAssetStudio/index.html

Setting Android Theme background color

I'm trying to modify the default background theme color, which should be easy but surprisingly I can't get it working. Please note that I want the change to be across the entire app, not just for a single activity. Here is my code:
styles.xml
<resources>
<color name="white_opaque">#FFFFFFFF</color>
<color name="pitch_black">#FF000000</color>
<style name="AppTheme" parent="android:Theme.Light">
<item name="android:background">#color/white_opaque</item>
<item name="android:windowBackground">#color/white_opaque</item>
<item name="android:colorBackground">#color/white_opaque</item>
</style>
</resources>
and of course in the manifest
<application
.
.
.
android:theme="#style/AppTheme" >
</application>
Android doc which I consulted on modifying themes:
http://developer.android.com/guide/topics/ui/themes.html
I've tried switching between white_opaque and pitch_black for all the xml attributes but it doesn't change a thing. Any suggestions?

Okay turned out that I made a really silly mistake. The device I am using for testing is running Android 4.0.4, API level 15.
The styles.xml file that I was editing is in the default values folder. I edited the styles.xml in values-v14 folder and it works all fine now.

<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="android:Theme.Holo.NoActionBar">
<item name="android:windowBackground">#android:color/black</item>
</style>
</resources>

Open res -> values -> styles.xml and to your <style> add this line replacing with your image path <item name="android:windowBackground">#drawable/background</item>. Example:
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- 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:windowBackground">#drawable/background</item>
</style>
</resources>
There is a <item name ="android:colorBackground">#color/black</item> also, that will affect not only your main window background but all the component in your app. Read about customize theme here.
If you want version specific styles:
If a new version of Android adds theme attributes that you want to
use, you can add them to your theme while still being compatible with
old versions. All you need is another styles.xml file saved in a
values directory that includes the resource version qualifier. For
example:
res/values/styles.xml # themes for all versions
res/values-v21/styles.xml # themes for API level 21+ only
Because the styles in the values/styles.xml file are available for all
versions, your themes in values-v21/styles.xml can inherit them. As
such, you can avoid duplicating styles by beginning with a "base"
theme and then extending it in your version-specific styles.
Read more here(doc in theme).