page.title=Applying Styles and Themes parent.title=User Interface parent.link=index.html @jd:body

In this document

Defining Styles
1. Inheritance
2. Style Properties
Applying Styles and Themes to the UI
1. Apply a style to a View
2. Apply a theme to an Activity or application
Using Platform Styles and Themes

Defining Styles

To create a set of styles, save an XML file in the {@code res/values/} directory of your project. The name of the XML file is arbitrary, but it must use the {@code .xml} extension and be saved in the {@code res/values/} folder.

The root node of the XML file must be {@code <resources>}.

For each style you want to create, add a {@code <style>} element to the file with a {@code name} that uniquely identifies the style (this attribute is required). Then add an {@code <item>} element for each property of that style, with a {@code name} that declares the style property and a value to go with it (this attribute is required). The value for the {@code <item>} can be a keyword string, a hex color, a reference to another resource type, or other value depending on the style property. Here's an example file with a single style:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="CodeFont" parent="@android:style/TextAppearance.Medium">
        <item name="android:layout_width">fill_parent</item>
        <item name="android:layout_height">wrap_content</item>
        <item name="android:textColor">#00FF00</item>
        <item name="android:typeface">monospace</item>
    </style>
</resources>

Each child of the {@code <resources>} element is converted into an application resource object at compile-time, which can be referenced by the value in the {@code <style>} element's {@code name} attribute. This example style can be referenced from an XML layout as {@code @style/CodeFont} (as demonstrated in the introduction above).

The parent attribute in the {@code <style>} element is optional and specifies the resource ID of another style from which this style should inherit properties. You can then override the inherited style properties if you want to.

Remember, a style that you want to use as an Activity or application theme is defined in XML exactly the same as a style for a View. A style such as the one defined above can be applied as a style for a single View or as a theme for an entire Activity or application. How to apply a style for a single View or as an application theme is discussed later.

Inheritance

The {@code parent} attribute in the {@code <style>} element lets you specify a style from which your style should inherit properties. You can use this to inherit properties from an existing style and then define only the properties that you want to change or add. You can inherit from styles that you've created yourself or from styles that are built into the platform. (See Using Platform Styles and Themes, below, for information about inheriting from styles defined by the Android platform.) For example, you can inherit the Android platform's default text appearance and then modify it:

    <style name="GreenText" parent="@android:style/TextAppearance">
        <item name="android:textColor">#00FF00</item>
    </style>

If you want to inherit from styles that you've defined yourself, you do not have to use the parent attribute. Instead, just prefix the name of the style you want to inherit to the name of your new style, separated by a period. For example, to create a new style that inherits the CodeFont style defined above, but make the color red, you can author the new style like this:

    <style name="CodeFont.Red">
        <item name="android:textColor">#FF0000</item>
    </style>

Notice that there is no {@code parent} attribute in the {@code <style>} tag, but because the {@code name} attribute begins with the {@code CodeFont} style name (which is a style that you have created), this style inherits all style properties from that style. This style then overrides the {@code android:textColor} property to make the text red. You can reference this new style as {@code @style/CodeFont.Red}.

You can continue inheriting like this as many times as you'd like, by chaining names with periods. For example, you can extend {@code CodeFont.Red} to be bigger, with:

    <style name="CodeFont.Red.Big">
        <item name="android:textSize">30sp</item>
    </style>

This inherits from both {@code CodeFont} and {@code CodeFont.Red} styles, then adds the {@code android:textSize} property.

Note: This technique for inheritance by chaining together names only works for styles defined by your own resources. You can't inherit Android built-in styles this way. To reference a built-in style, such as {@link android.R.style#TextAppearance}, you must use the {@code parent} attribute.

Style Properties

Now that you understand how a style is defined, you need to learn what kind of style properties—defined by the {@code <item>} element—are available. You're probably familiar with some already, such as {@link android.R.attr#layout_width} and {@link android.R.attr#textColor}. Of course, there are many more style properties you can use.

The best place to find properties that apply to a specific {@link android.view.View} is the corresponding class reference, which lists all of the supported XML attributes. For example, all of the attributes listed in the table of TextView XML attributes can be used in a style definition for a {@link android.widget.TextView} element (or one of its subclasses). One of the attributes listed in the reference is {@code android:inputType}, so where you might normally place the {@code android:inputType} attribute in an {@code <EditText>} element, like this:

<EditText
    android:inputType="number"
    ... />

You can instead create a style for the {@link android.widget.EditText} element that includes this property:

<style name="Numbers">
  <item name="android:inputType">number</item>
  ...
</style>

So your XML for the layout can now implement this style:

<EditText
    style="@style/Numbers"
    ... />

This simple example may look like more work, but when you add more style properties and factor-in the ability to re-use the style in various places, the pay-off can be huge.

For a reference of all available style properties, see the {@link android.R.attr} reference. Keep in mind that all View objects don't accept all the same style attributes, so you should normally refer to the specific {@link android.view.View} class for supported style properties. However, if you apply a style to a View that does not support all of the style properties, the View will apply only those properties that are supported and simply ignore the others.

Some style properties, however, are not supported by any View element and can only be applied as a theme. These style properties apply to the entire window and not to any type of View. For example, style properties for a theme can hide the application title, hide the status bar, or change the window's background. These kind of style properties do not belong to any View object. To discover these theme-only style properties, look at the {@link android.R.attr} reference for attributes that begin with {@code window}. For instance, {@code windowNoTitle} and {@code windowBackground} are style properties that are effective only when the style is applied as a theme to an Activity or application. See the next section for information about applying a style as a theme.

Note: Don't forget to prefix the property names in each {@code <item>} element with the android: namespace. For example: {@code <item name="android:inputType">}.

Applying Styles and Themes to the UI

There are two ways to set a style:

To an individual View, by adding the style attribute to a View element in the XML for your layout.
Or, to an entire Activity or application, by adding the android:theme attribute to the <activity> or <application> element in the Android manifest.

When you apply a style to a single {@link android.view.View} in the layout, the properties defined by the style are applied only to that {@link android.view.View}. If a style is applied to a {@link android.view.ViewGroup}, the child {@link android.view.View} elements will not inherit the style properties—only the element to which you directly apply the style will apply its properties. However, you can apply a style so that it applies to all {@link android.view.View} elements—by applying the style as a theme.

To apply a style definition as a theme, you must apply the style to an {@link android.app.Activity} or application in the Android manifest. When you do so, every {@link android.view.View} within the Activity or application will apply each property that it supports. For example, if you apply the {@code CodeFont} style from the previous examples to an Activity, then all View elements that support the text style properties will apply them. Any View that does not support the properties will ignore them. If a View supports only some of the properties, then it will apply only those properties.

Apply a style to a View

Here's how to set a style for a View in the XML layout:

<TextView
    style="@style/CodeFont"
    android:text="@string/hello" />

Now this TextView will be styled as defined by the style named {@code CodeFont}. (See the sample above, in Defining Styles.)

Note: The style attribute does not use the android: namespace prefix.

Apply a theme to an Activity or application

To set a theme for all the activities of your application, open the {@code AndroidManifest.xml} file and edit the <application> tag to include the android:theme attribute with the style name. For example:

<application android:theme="@style/CustomTheme">

If you want a theme applied to just one Activity in your application, then add the android:theme attribute to the <activity> tag instead.

Just as Android provides other built-in resources, there are many pre-defined themes that you can use, to avoid writing them yourself. For example, you can use the {@code Dialog} theme and make your Activity appear like a dialog box:

<activity android:theme="@android:style/Theme.Dialog">

Or if you want the background to be transparent, use the Translucent theme:

<activity android:theme="@android:style/Theme.Translucent">

If you like a theme, but want to tweak it, just add the theme as the parent of your custom theme. For example, you can modify the traditional dialog theme to use your own background image like this:

<style name="CustomDialogTheme" parent="@android:style/Theme.Dialog">
    <item name="android:windowBackground">@drawable/custom_dialog_background</item>
</style>

Now use {@code CustomDialogTheme} instead of {@code Theme.Dialog} inside the Android Manifest:

<activity android:theme="@style/CustomDialogTheme">

Using Platform Styles and Themes

The Android platform provides a large collection of styles and themes that you can use in your applications. You can find a reference of all available styles in the {@link android.R.style} class. To use the styles listed here, replace all underscores in the style name with a period. For example, you can apply the {@link android.R.style#Theme_NoTitleBar} theme with {@code "@android:style/Theme.NoTitleBar"}.

The {@link android.R.style} reference, however, is not well documented and does not thoroughly describe the styles, so viewing the actual source code for these styles and themes will give you a better understanding of what style properties each one provides. For a better reference to the Android styles and themes, see the following source code:

These files will help you learn through example. For instance, in the Android themes source code, you'll find a declaration for <style name="Theme.Dialog">. In this definition, you'll see all of the properties that are used to style dialogs that are used by the Android framework.

For more information about the syntax used to create styles in XML, see Available Resource Types: Style and Themes.

For a reference of available style attributes that you can use to define a style or theme (e.g., "windowBackground" or "textAppearance"), see {@link android.R.attr} or the respective View class for which you are creating a style.