Android Inter-Module Navigation with Dagger

Robinhood's Android team cracked a tough modularization puzzle: how do you navigate between completely decoupled feature modules without creating dependencies?

Jin Cao from Robinhood Engineering shares their solution for inter-module navigation using Dagger's multibinding capabilities. This follow-up to their modularization story tackles the practical challenge of communication between independent feature modules while maintaining compile-time safety and fast build times.

Key Takeaways

• Uses Dagger multibinding to create navigation map without cross-module dependencies
• IntentKey classes provide compile-time safety for navigation arguments
• Debug builds gracefully handle missing modules to enable selective loading
• Developers can unload unused modules for faster builds without crashes
• Pattern works for activities, fragments, and views across independent modules

The debug implementation includes a clever trick that lets engineers work on one feature while completely ignoring the rest of the app.