In May 2019, when Google first announced that they were working on a new declarative UI framework for Android, we couldn’t have been more excited. The idea of moving away from old XML layouts and writing UI entirely in Kotlin was a dream for many Android developers. That dream quickly became a reality, and today, Jetpack Compose is already an industry standard.
Why Jetpack Compose?
This new UI toolkit has revolutionized how we build Android applications. With its declarative paradigm, Compose allows developers to define UI components in a more intuitive, flexible, and scalable manner. It simplifies many aspects of UI development, but let’s focus on the most important ones.
Simpler UI components
Previously, whether using Activities, Fragments, or custom Views, even the simplest UI required an XML layout, a Kotlin class to control it, and additional boilerplate code to connect the two. Passing arguments or handling events made things even more complicated.
With Jetpack Compose, creating a UI component is as simple as defining a Kotlin function. Like any other function, it accepts arguments to receive data and uses lambda callbacks to send events back. This fundamental change simplifies UI development, saves time, and encourages modular and reusable components.
Less boilerplate code
If you’ve ever worked with Android, you’ve likely encountered RecyclerView—a key component for displaying long scrollable lists. Implementing even a simple list of names required around 50 lines of code. The same applies to ViewPager with tabs, complex forms, nested scrolling, or dialogs.
With Jetpack Compose, many of these previously complex implementations now require only a few lines of code. Developers can focus more on delivering business value and enhancing app quality rather than struggling with implementation details.
Better state management
Historically, Android apps lacked a consistent approach to UI state management. Over the years, various methods emerged, each with its pros and cons.
Jetpack Compose strongly promotes Unidirectional Data Flow (UDF), making state management clearer and more intuitive. The fundamental principle is simple: state flows down, and events flow up. This approach makes state management more predictable, less error-prone, and easier to debug.
Delightful UI
In today’s competitive market, a polished UI and seamless UX can set an app apart. Beautiful designs, smooth animations, and thoughtful details make a significant difference in user retention. However, achieving this with the traditional View system required extensive expertise and mastery of complex APIs.
Jetpack Compose simplifies this process by shifting theming and styling from XML to Kotlin. It provides a powerful Modifier system for UI customization and enhanced animation APIs for intuitive and visually appealing interactions. Creating delightful user experiences has never been easier.
Interoperability
A new UI framework wouldn’t be practical if it couldn’t integrate into existing applications. Fortunately, the Jetpack Compose team has provided APIs to seamlessly mix old Views with new Compose components. Developers can:
- Embed small composables within large XML layouts
- Add XML components to new Compose screens
- Display Compose UI inside Activities or Fragments
- Integrate Fragments or Activities as destinations in Compose Navigation
- And many more …
This interoperability allows for a smooth migration without disrupting ongoing development.
Challenges of moving to Jetpack Compose
Despite its many advantages, transitioning to Jetpack Compose presents challenges, especially for developers accustomed to the traditional View system. Old habits can often lead to confusion and mistakes, making the shift even more difficult. Here are some key areas to consider.
Rethinking UI structure
Adopting Jetpack Compose isn’t just about learning new syntax and APIs. It requires a shift in mindset. Developers accustomed to the traditional View system may find themselves unintentionally applying old patterns, which can lead to confusion and mistakes. Using Compose the same way as Views limits its benefits, so embracing its declarative nature is crucial for unlocking its full potential.
State management differences
While Compose’s UDF approach simplifies state handling, it may have a learning curve for developers unfamiliar with this pattern. Developers used to traditional state management methods might find themselves clinging to previous state management patterns, which can cause inefficiencies, unexpected UI updates, and difficulty debugging state changes. Understanding and fully embracing UDF takes time and practice, but once mastered, it significantly improves the clarity and predictability of state management.
New best practices for forms
Traditionally, forms stored data inside ViewModels wrapped with data streams like StateFlow. While this approach worked well with the View-based system, Google found that in Jetpack Compose, it can lead to unexpected behaviours, and UI inconsistencies. They now recommend a different approach to handling form state, requiring developers to adapt to new patterns and rethink their existing workflows. Adapting to these new best practices requires developers to rethink how they manage user input and validation within Compose applications.
Navigation paradigm shift
Compose Navigation introduces a paradigm that closely resembles web-based routing rather than the traditional Jetpack Navigation component. While this approach offers significant flexibility, it also comes with new constraints and behaviors that may be unexpected for developers accustomed to the previous solution. Adapting to these changes requires rethinking navigation strategies and understanding the nuances of Compose’s navigation framework.
Risk of overoptimization
Jetpack Compose offers many performance optimization techniques that can significantly enhance UI responsiveness and efficiency. However, with a variety of available optimizations, developers may find themselves prematurely applying techniques without fully assessing their necessity. Over-optimizing can lead to unnecessary complexity, making the code harder to maintain and potentially introducing new performance bottlenecks. Understanding the impact of each optimization and applying them only when justified ensures a balanced approach, keeping the codebase both efficient and readable.
Introducing our Compose Guidelines
At Droids On Roids, we’ve been using Jetpack Compose from its early days, building exceptional mobile products over the last couple of years. We faced all these challenges firsthand, and we have battle-tested solutions to properly overcome them.
This article kicks off a series of blog posts showing what works well for our mobile teams. We are going to share many insights and guidelines on how to use Jetpack Compose to build robust applications, maximizing effectiveness and app quality at the same time. The series will cover various aspects of Compose development, such as:
Effective screens
Screens are the core of any mobile application, serving as the primary interface between users and the app’s functionality. In our first post, we’ll take a deep dive into best practices for structuring screens in a way that enhances maintainability and scalability. We’ll explore techniques for efficiently managing state, ensuring smooth interactions, and handling different UI scenarios such as loading states, errors, and dynamic content updates.
Reusable UI components
Many screens share common UI elements, making it essential to design reusable components that are modular, independent, and adaptable. A well-structured component should seamlessly integrate with various screens while maintaining clear state management and interaction patterns. We’ll explore best practices for building highly flexible UI elements, ensuring they are efficient, maintainable, and scalable across different application scenarios.
Composable forms
Forms are a unique type of UI components that require careful handling of state, validation, and user interactions. Unlike other UI elements, forms must dynamically respond to user input while maintaining data consistency and validation rules. In this section, we’ll delve into techniques for constructing composable forms that function like LEGO blocks—modular, reusable, and easy to integrate into different parts of an application.
Scalable navigation
Navigating between screens in Jetpack Compose is straightforward, but as applications grow, managing navigation efficiently becomes increasingly complex. Large-scale projects require thoughtful structuring to maintain clarity and flexibility. Based on our extensive experience, we’ll share strategies for handling navigation at scale, including techniques for organizing multiple navigation graphs, efficiently passing arguments between destinations, and maintaining a clean and maintainable architecture.
Use cases for Composition Local
This often-overlooked feature serves as a powerful mechanism for providing global functionalities and contextual data throughout a Compose hierarchy without requiring explicit parameter passing. By utilizing CompositionLocal, developers can efficiently share common UI-related information, such as themes, configurations, or localization settings, improving modularity and reducing boilerplate code.
Simple animations
With Jetpack Compose, adding animations and transitions to your application is no longer a daunting task. The framework makes it incredibly straightforward to implement smooth, engaging motion effects that enhance user experience. These subtle yet impactful details bring interfaces to life, making interactions feel more fluid and intuitive. In this section, we’ll explore just how simple it is to integrate beautiful animations into your app.
Reasonable performance optimization
Ensuring optimal application performance is always a priority, but equally important is recognizing when optimizations are unnecessary and may introduce needless complexity. In the final post of this series, we’ll explore various optimization techniques available in Jetpack Compose, discussing when they truly enhance performance and when they might be redundant or even counterproductive.
Summary
Jetpack Compose offers a modern, declarative way to build Android UIs, significantly reducing boilerplate code and making UI development more intuitive. However, transitioning to Compose comes with its own set of challenges, requiring developers to rethink traditional approaches and embrace new patterns. In this series of articles, we will share our battle-tested solutions and best practices to help developers navigate these challenges effectively. Stay tuned as we guide you through making the most of Jetpack Compose in real-world applications.
