Modern Android Architecture (Part 3): Refactoring a Product Detail Page with Lego Architecture: From 3000 Lines to 15 Standalone Components

goodlords Posted on Jun 1 Modern Android Architecture (Part 3): Refactoring a Product Detail Page with Lego Architecture: From 3000 Lines to 15 Standalone Components # android # architecture # mobile # tutorial Series Navigation : Article 1: A Decade of Android Architecture Evolution | Article 2: The Lego Architecture: Divide and Conquer, Taken to the Extreme | Article 4: Design Patterns — The Glue of Lego Architecture Project Repository : https://github.com/zealot2002/androidArch Foreword: Product Detail Page — The "Touchstone" of Architecture The product detail page is widely recognized as the "touchstone" of e-commerce app architecture. A standard detail page typically contains over 10 business sections: image carousel, price marketing, specification selection, user reviews, store information, product details, recommended products... In traditional architecture, we've seen too many real and painful disasters: Unclear overall control logic, no real "traffic hub" : Page control logic is scattered across Activity, Fragment, Adapter, and even utility classes. You find code loading data in Activity, follow the call chain to ViewModel, then it might end up in an Adapter's internal callback. There's no centralized place to see "what this page does in what order." Severe code redundancy : Redundant logic and slightly different code snippets are scattered everywhere. Either you don't know how to extract methods — always feeling the method name would be longer than the code itself — or you force an extraction that does multiple things (a method called updatePrice that also refreshes inventory, logs analytics, and shows a Toast). Scattered glue code everywhere : Temporary flags, anonymous callbacks, nested conditionals... scattered throughout, reading like a book without table of contents or chapters. Chaotic organization, vague responsibility boundaries : Although seemingly divided into classes or packages, data conversion, UI rendering, and business logic are often intert