How to Implement Dark Mode in Android Apps Using Kotlin

Implementing dark mode in Android apps has become a crucial aspect of modern app development, enhancing user experience and conserving battery life on devices with OLED screens. In this guide, we will walk through the essential steps to implement dark mode using Kotlin, focusing on practical methods that can be easily integrated into your projects.

Step 1: Update Your App Theme

The first step in implementing dark mode is to update your app theme. This involves modifying the themes.xml file located in the res/values directory of your project. Here, you can define both light and dark themes for your application . For instance:

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here -->
</style>

<style name="AppTheme.Dark" parent="Theme.AppCompat.DayNight.NoActionBar">
    <!-- Customize your dark theme here -->
</style>

These styles allow you to switch between light and dark modes seamlessly based on user preferences or system settings.

Step 2: Define Colors for Light and Dark Modes

To ensure consistency across different themes, it’s important to define color resources separately for light and dark modes. Create two colors.xml files: one in the res/values directory for light mode and another in res/values-night for dark mode . Here’s how you might define them:

res/values/colors.xml

<color name="primaryColor">#FF0000</color>

res/values-night/colors.xml

<color name="primaryColor">#00FF00</color>

This setup allows Android to automatically select the appropriate colors based on the current theme.

Step 3: Implementing Theme Switching

Creating a toggle for users to switch between light and dark modes enhances usability. You can add a switch widget in your settings screen and use shared preferences or DataStore to save the user’s choice . Here’s a simple example of switching themes programmatically:

val sharedPreferences = getSharedPreferences("settings", Context.MODE_PRIVATE)
val editor = sharedPreferences.edit()

// When user selects dark mode
AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)

// When user selects light mode
AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)

Step 4: Apply Themes in Activities

Ensure all activities respect the selected theme by applying the theme before setting content view in each activity’s onCreate() method:

override fun onCreate(savedInstanceState: Bundle?) {
    setTheme(R.style.AppTheme_Dark) // Or R.style.AppTheme depending on preference
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
}

Conclusion

Implementing dark mode not only improves visual comfort but also aligns with current design trends and energy efficiency standards. By following these steps—updating your app theme, defining colors, enabling theme switching, and applying themes consistently—you can effectively integrate dark mode into your Android applications using Kotlin .

Whether you’re starting from scratch or updating an existing app, incorporating dark mode support ensures your app remains competitive and user-friendly in today’s market.