UI and content for billions

Make sure that your app offers an interactive UI that responds quickly to user input and, if necessary, compensates for a slow launch. Ensure that your app is designed to be easily localized by accommodating the variations between languages: allow for spacing, density, order, emphasis, and wording variations. Also make sure that date, time, and other units are internationalized and displayed according to the phone’s settings.

Fast and responsive user interface

The user's perception of app performance is formed in large part by the app's responsiveness. For example, interaction with the user and a crisp display are two important characteristics of a performant app. Here you can find tips on how to optimize these and other aspects of an app's speed and responsiveness.

Touch feedback on all touchable items

Touch feedback adds a tactile feeling to the user interface. You should ensure your app provides touch feedback on all touchable elements to reduce the perceived app latency as much as possible.
Responsive interaction encourages deeper exploration of an app by creating timely, logical, and delightful screen reactions to user input. Responsive interaction elevates an app from an information-delivery service to an experience that communicates using multiple visual and tactile responses.
For more information, see the Android training on Customizing Touch Feedback.

UI should always be interactive

Apps that are unresponsive when performing background activity feel slow and reduce user satisfaction. Ensure your app always has a responsive UI regardless of any background activity. Achieve this by performing network operations or any heavy-duty operations in a background thread—keep the UI thread as idle as you can.
Material Design apps use minimal visual changes when loading content by representing each operation with a single activity indicator. Avoid blocking dialogs with loading indicators.
Empty states occur when a view has no content to show. It might be a list that has no items or a search that returns no results. Avoid empty states using starter, educational, or best match content. When these options aren’t applicable display a non-interactive image and a text tagline that tell the user what they’ll see when there is something to display.
For more information, see the Android training on Keeping Your App Responsive.

Target 60 frames per second on low-cost devices

Ensure that your app always runs fast and smoothly, even on low-cost devices.
Overdraw can significantly slow down your app—it occurs when the pixels are being drawn more than once per pass. An example of this is when you have an image with a button placed on top of it. While some overdraw is unavoidable, it should be minimized to ensure a smooth frame rate. Perform Debug GPU overdraw on your app to ensure it’s minimized.
Android devices refresh the screen at 60 frames per second (fps), meaning your app has to update the screen within roughly 16 milliseconds. Profile your app using on-device tools to see if and when your app is not meeting this 16 ms average.
Reduce or remove animations on low-cost devices to lessen the burden on the device’s CPU and GPU. For more information, see Improve layout performance.
An efficient view hierarchy can speed up your app without increasing the app's memory footprint. For more information, see Performance and View Hierarchies.

Use a launch screen on slow to start apps

The launch screen is a user’s first experience of your application. Displaying a blank canvas while launching your app increases the perception of its loading time, so consider using a placeholder UI or a branded launch screen to reduce the perceived loading time.
A placeholder UI is the most seamless launch transition, appropriate for both app launches and in-app activity transitions.
Branded launch screens provide momentary brand exposure, freeing the UI to focus on content.
The best way to deal with slow start speeds is not to have them. Launch-Time Performance provides information that may help you speed up your app's launch time.

User interface best practices

Material Design is a visual language that synthesizes the classic principles of good design with the innovation and possibility of technology and science. Material Design provides a single underlying system that allows for a unified experience across platforms and device sizes. Consider using key Material Design components so that users intuitively know how to use your app.
Ready-to-use Material Design components are available in the Material Design Support library. These components are supported in Android 2.1 (API level 7) and above.

Localization

Your users could be from any part of the world and their first language may not be yours. If you don’t present your app in a language that your users can read, it is a missed opportunity. You should therefore localize your app for key regional languages.
To learn more, visit the Android training on Supporting Different Languages and see the localization checklist.
Starting from Android 7.0 (API level 24), the Android framework makes available a subset of the ICU4J APIs, which can help you localize your app into multiple languages. For more information, see ICU4J Android Framework APIs.