How to set custom ActionBar color / style?

For Android 3.0 and higher only

When supporting Android 3.0 and higher only, you can define the action bar's background like this:

res/values/themes.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- the theme applied to the application or activity -->
    <style name="CustomActionBarTheme" parent="@style/Theme.Holo.Light.DarkActionBar">
       <item name="android:actionBarStyle">@style/MyActionBar</item>
    </style>

<!-- ActionBar styles -->
  <style name="MyActionBar" parent="@style/Widget.Holo.Light.ActionBar.Solid.Inverse">
       <item name="android:background">#ff0000</item>
  </style>
</resources>

For Android 2.1 and higher

When using the Support Library, your style XML file might look like this:

<?xml version="1.0" encoding="utf-8"?>
  <resources>
  <!-- the theme applied to the application or activity -->
 <style name="CustomActionBarTheme" parent="@style/Theme.AppCompat.Light.DarkActionBar">
    <item name="android:actionBarStyle">@style/MyActionBar</item>

    <!-- Support library compatibility -->
    <item name="actionBarStyle">@style/MyActionBar</item>
</style>

<!-- ActionBar styles -->
<style name="MyActionBar"
       parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
    <item name="android:background">@drawable/actionbar_background</item>

    <!-- Support library compatibility -->
    <item name="background">@drawable/actionbar_background</item>
  </style>
 </resources>

Then apply your theme to your entire app or individual activities:

for more details Documentaion

You can define the color of the ActionBar (and other stuff) by creating a custom Style:

Simply edit the res/values/styles.xml file of your Android project.

For example like this:

<resources>
    <style name="MyCustomTheme" parent="@android:style/Theme.Holo.Light">
        <item name="android:actionBarStyle">@style/MyActionBarTheme</item>
    </style>

    <style name="MyActionBarTheme" parent="@android:style/Widget.Holo.Light.ActionBar">
        <item name="android:background">ANY_HEX_COLOR_CODE</item>
    </style>
</resources>

Then set "MyCustomTheme" as the Theme of your Activity that contains the ActionBar.

You can also set a color for the ActionBar like this:

ActionBar actionBar = getActionBar();
actionBar.setBackgroundDrawable(new ColorDrawable(Color.RED)); // set your desired color

Taken from here: How do I change the background color of the ActionBar of an ActionBarActivity using XML?

In general Android OS leverages a “theme” to allow app developers to globally apply a universal set of UI element styling parameters to Android applications as a whole, or, alternatively, to a single Activity subclass.

So there are three mainstream Android OS “system themes,” which you can specify in your Android Manifest XML file when you are developing apps for Version 3.0 and later versions

I am referring the (APPCOMPAT)support library here:-- So the three themes are 1. AppCompat Light Theme (Theme.AppCompat.Light)

2. AppCompat Dark Theme(Theme.AppCompat),

3. And a hybrid between these two ,AppCompat Light Theme with the Darker ActionBar.( Theme.AppCompat.Light.DarkActionBar)

AndroidManifest.xml and see the tag, the android theme is mentioned as:-- android:theme="@style/AppTheme"

Open the Styles.xml and we have base application theme declared there:--

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
  </style>

We need to override these parent theme elements to style the action bar.

ActionBar with different color background:--

To do this we need to create a new style MyActionBar(you can give any name) with a parent reference to @style/Widget.AppCompat.Light.ActionBar.Solid.Inverse that holds the style characteristics for the Android ActionBar UI element. So definition would be

<style name="MyActionBar" parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
    <item name="background">@color/red</item>
</style>

And this definition we need to reference in our AppTheme, pointing to overridden ActionBar styling as--

@style/MyActionBar

Change the title bar text color (e.g black to white):--

Now to change the title text color, we need to override the parent reference parent="@style/TextAppearance.AppCompat.Widget.ActionBar.Title">

So the style definition would be

<style name="MyActionBarTitle" parent="@style/TextAppearance.AppCompat.Widget.ActionBar.Title">
    <item name="android:textColor">@color/white</item>
</style>

We’ll reference this style definition inside the MyActionBar style definition, since the TitleTextStyle modification is a child element of an ActionBar parent OS UI element. So the final definition of MyActionBar style element will be

<style name="MyActionBar" parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
    <item name="background">@color/red</item>
    <item name="titleTextStyle">@style/MyActionBarTitle</item>
</style>

SO this is the final Styles.xml

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light">
        <!-- This is the styling for action bar -->
        <item name="actionBarStyle">@style/MyActionBar</item>
    </style>

    <style name="MyActionBar" parent="@style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
        <item name="background">@color/red</item>
        <item name="titleTextStyle">@style/MyActionBarTitle</item>
    </style>

    <style name="MyActionBarTitle" parent="@style/TextAppearance.AppCompat.Widget.ActionBar.Title">
        <item name="android:textColor">@color/white</item>
    </style>
</resources>

For further ActionBar options Menu styling, refer this link