Theme | Android

Introduction

A style (similar to stylesheets in web design) is a collection of attributes that specify the appearance for a single View. It can specify attributes such as font color, font size, background color, and much more. A theme is a type of style that’s applied to an entire app, activity, or view hierarchy. When you apply style as a theme, every view in the app or activity applies each style attribute that it supports.

Styles and themes are declared in a style resource file in res/values/styles.xml.

Create Theme

To create a new theme, follow these steps in res/values/styles.xml

• Add a <style> element with a name that uniquely identifies the style.
• Add an <item> element for each style attribute you want to define. The name in each item specifies an attribute, value in the <item> element is the value for that attribute.

To extend a style, specify the base style using parent attribute. You can then override the inherited style attributes and add new ones.

<style name="Theme" parent="Theme.AppCompat.Light.DarkActionBar">
  <item name="colorPrimary">#FF0000</item>
  <item name="colorPrimaryDark">#0000FF</item>
  <item name="colorAccent">#00FF00</item>    
  <item name="actionMenuTextColor">#0000FF</item>
  <item name="android:textColor">#00FF00</item>
</style>

In the above example, Theme derived from parent theme, where

• colorPrimary – Color of the app bar.
• colorPrimaryDark – Color of the status bar and contextual app bars; this is normally a dark version of colorPrimary.
• colorAccent – Color of UI controls such as check boxes, radio buttons, and edit text boxes.
• windowBackground – Color of the screen background.
• textColorPrimary – Color of UI text in the app bar.
• statusBarColor – Color of the status bar.
• navigationBarColor – Color of the navigation bar.

Apply Theme

Apply a theme with the android:theme attribute on either the <application> tag or an <activity> tag in the AndroidManifest.xml file.

<!--Code snippet of AndroidManifest.xml -->
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.aphalaprepsunaa.picturepuzzle">

  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

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

    <activity
      android:name=".activity.SplashActivity"
      android:theme="@style/SplashTheme">
      <intent-filter>
          <action android:name="android.intent.action.MAIN" />
          <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
  </application>

</manifest>