Android App Design

Android, the world's most popular operating system, is built on Linux and open-source, shaping how designers develop apps across various devices. Google manages the core Android project, but manufacturers can customize the source code to suit their hardware. This flexibility results in a wide range of Android experiences.

Device manufacturers customize Android's appearance and functionality through custom software overlays, called UI skins. Samsung's One UI, Sony's Xperia UI, and Google's Pixel UI represent distinct interpretations of the Android platform. These manufacturer-specific modifications create unique design considerations for each Android variant.

Designers must account for these different Android implementations when creating applications. Each app's interface should maintain consistency with the underlying system UI while adhering to Material Design principles that ensure platform-wide usability.

The Android ecosystem encompasses devices from numerous manufacturers, each bringing unique approaches to hardware and software design. Brands like Samsung, Google, OnePlus, OPPO, Motorola, Sony, and Nothing offer unique alternatives with specialized features.

The versatility of Android extends far beyond mobile devices. Smart home systems, automotive interfaces, and entertainment devices leverage Android's adaptable architecture to create specialized experiences. This flexibility enables manufacturers to optimize the operating system for specific use cases, from voice-controlled displays to car infotainment systems.

Connected devices require robust mobile interfaces for control and monitoring. Android's widespread adoption has fostered a rich ecosystem of companion apps that bridge the gap between traditional mobile interfaces and emerging smart device categories. This interconnected environment demands thoughtful design considerations for seamless cross-device experiences.

Android architecture, or the Android stack, consists of 5 layers:

• Linux Kernel exists at the root of Android architecture. The kernel handles device drivers, power, memory, device management, and resource access.
• Native Libraries like WebKit, OpenGL, FreeType, and others are on top of the Linux Kernel. They support browsers, fonts, databases, video, and audio.
• Android Runtime provides the base for the application framework and powers applications with the help of the core libraries.
• Application Framework includes Android UI, telephony, resources, locations, data, and package managers. It provides a lot of classes and interfaces for android application development.
• Applications form the top layer of the Android stack. Pre-installed apps like home, contacts, camera, and third-party apps like social networks will be installed on this layer.

Average Android users primarily interact with the Applications layer when using apps (making phone calls, surfing the internet, etc.). The layers further down are usually just accessed by developers.

Android offers countless customization possibilities to its users. Let's have a look at the most prominent ones:

• Home screen: Android’s Home screen doesn't follow a rigid layout, so users can arrange app icons in any chosen pattern. They can also add widgets, calendars, different time displays, and other features.
• Launcher Apps: Apps like Nova and Niagara allow users to change the look of Android completely. For example, they allow users to add more icons to the dock, have wallpapers that change over time, or use custom navigation gestures.
• Default apps: Users can set a default app for many tasks: messaging, emailing, browsing, typing, and calling.
• Dual messaging: Samsung offers Dual messenger on their dual-SIM Android phones. It lets you use two different accounts with one chatting app like WhatsApp or Viber.
• Installing apps without the Play Store: Android allows users to install apps through third-party app stores like Amazon's App Store or manually by downloading APKs.
• Android rooting: Rooting an Android device gives users unrestricted access to the system files so that they can modify the software code. However, many apps (like banking apps, Google Pay, and some games) may not work on rooted devices due to security concerns. It also voids warranties on most devices and can lead to system instability if done incorrectly.

Android navigation provides multiple ways to access different sections of an app through distinct interface components. Each component serves a specific navigational purpose in the Android ecosystem.

• Bottom navigation bars facilitate movement between 3-5 primary destinations within an app. They remain consistently visible at the screen's bottom, allowing users to switch between main sections like Home, Search, or Profile with a single tap. This pattern works well for apps with clearly distinct top-level sections.
• Tabs organize peer content or views within the same hierarchy level. Different tab implementations include fixed tabs (showing all options simultaneously) and scrolling tabs (for larger sets of options). Tabs work best when users need to switch frequently between related categories or views.
• The hamburger menu, or navigation drawer, contains supplementary navigation options that don't require constant visibility. This component typically slides in from the left edge, housing secondary features like Settings, Help, or Account Management. The menu icon (☰) serves as a consistent access point across Android applications.

The floating action button (FAB) highlights the most important primary action on an Android screen through its distinctive shape and prominent placement. According to the latest Material guidelines, FABs must feature a rounded square container that maintains strong contrast with the background, ensuring optimal visibility and interaction clarity.

There are 3 FAB sizes to accommodate various use cases and screen layouts. The standard FAB suits most scenarios, while the small FAB works in space-constrained interfaces. The large FAB provides an enhanced touch target and increased visibility for critical actions, particularly useful in tablet or desktop interfaces.

The button can be aligned left, center, or right, and positioned either above the navigation bar or nested within it. This adaptability ensures the FAB remains accessible while maintaining visual hierarchy across different screen sizes and orientations.^[1]

Material Design guidelines recommend making touch targets at least 48x48dp. Android’s device-independent pixels (dp) and Apple’s points (pt) are functionally equivalent. They refer to a baseline size that measures independent of the screen size — just like the CSS unit pixel (px).

Note that touch targets extend beyond the visual bounds of an element. For example, an icon may appear to be 24x24dp, but the padding surrounding it can comprise the full 48x48dp touch target. A 48x48dp touch target results in a physical size of about 9mm, regardless of screen size.

The Back button provides the primary way for users to navigate backward on Android devices. This essential navigation tool exists in 3 forms: a physical button on some devices, a software button at the bottom of the screen, and a gesture-based swipe from either edge on newer Android versions.

Back navigation follows a straightforward path through the user's recent screens. Each press of the Back button returns users to their previous screen, continuing until they reach the Home screen. This creates an intuitive way for users to retrace their steps through apps and system screens.

Some apps include an additional Back arrow in their top bar for specific navigation patterns. For example, Gmail uses this to help users return from a message to their inbox. This in-app back option works alongside the system Back button to provide clear navigation paths.

Action menus in Android appear when users tap the 3-dot kebab menu icon, providing access to additional options and functions. These menus typically display directly over their triggering element, creating a clear connection between the icon and its related actions.

Menu positioning adapts intelligently to screen space constraints. When triggered near the screen's top, menus expand downward to ensure all options remain visible and accessible. On newer Android versions, menus overlay the kebab icon itself and expand downward, creating a cleaner visual transition.

Bottom sheets offer an enhanced alternative to traditional menus when more space is needed. They slide up from the screen's bottom edge, providing room for extended content like detailed descriptions, larger touch targets, and supporting icons. This pattern works particularly well for complex action lists or when additional context is needed.

Android uses tabs to categorize related content into distinct, easily accessible groups. The system supports two tab types: primary tabs for main content destinations below the top app bar, and secondary tabs for organizing subcontent within a specific section.

Tabs maintain a peer relationship, appearing side-by-side to show equal hierarchy level. While the interface can accommodate multiple tabs through horizontal scrolling, each tab should represent a distinct content category rather than sequential content. For example, music genres, product categories, or filter options work well as tabs.

Tab design focuses on clarity and scannability. Labels can combine icons and text, but should remain concise to maintain readability. When designing tab layouts, avoid using them for step-by-step content that requires a specific viewing order — instead, use appropriate typography and spacing to create content hierarchy.^[2]

Roboto and Noto are the default typefaces on Android. Roboto is the standard typeface on Android, while Noto is the typeface for all languages not covered by Roboto (i.e., Chinese, Japanese, and Korean).^[3]

Roboto has been refined extensively to work across a wider set of supported platforms. It's similar to iOS's San Francisco but has taller letterforms and a bit more breathing room. Noto's vertical metrics are compatible with Roboto.

Designers can also use custom fonts. In fact, Google has a huge open-source collection named Google Fonts. These fonts are available to native apps on Android devices.