Modernising a Legacy Android App Architecture: Part Three - Applying the Refactor

Rob Pridham from BBC Sport reveals how his team tackled a massive Android refactor—migrating from multiple activities to a single-activity architecture while keeping the app running in production.

This is the final installment of a three-part series documenting BBC Sport's Android app modernization. The team applied MVVM+C architecture across their legacy codebase while consolidating dozens of activities into a unified fragment hierarchy. The work spanned August to December 2020 alongside ongoing feature development.

Key Takeaways

• Fragment replace vs add strategy: memory concerns killed the add approach
• WebView state restoration proved trickiest: scroll position fights required creative workarounds
• Shared ViewModels across fragments enabled complex multi screen onboarding flows
• Navigation responsibility cleanup required UX changes to rationalize ambiguous parent contexts
• Feature flagged development allowed parallel work until migration reached critical mass

The team's biggest regret about the refactor wasn't technical—it was about how they communicated progress to non-engineers.