Daehan Lim

Cubadebate News App

📝 Overview

📌 App Introduction: News reader app with personalized content delivery and offline storage capability
🕒 Duration: March 15, 2021 ~ June 30, 2021 (3.5 months)
📱 Platform: Native Android app
🏢 Company: Desoft (Cuba’s national software development company)
👥 Team Size: 1 developer
💼 Role: UI/UX design and complete Android app development
🛠️ Key Technologies: Android Kotlin Coroutines MVVM Room Retrofit Moshi Navigation Material Design Glide Lottie ViewBinding
🔗 GitHub: daehan-lim/cubadebate-app

📖 Project Background

Identified the need to develop a mobile-optimized news app to overcome Cuba’s challenging network environment (high data costs, unstable connections) and the limitations of the existing website-based news platform
The existing website required users an average of over 2 minutes to find articles of interest, with no way to customize content based on user preferences
Planned a transition to an native Android app that could provide data usage savings, offline accessibility, and personalization features
Aimed to help Cuban users access relevant news more easily through intuitive, accessible mobile UX including offline storage and voice support

🛠️ Tech Stack

📋 Project Structure

├── database/                        # Local database related classes
│   ├── CubadebateDatabase.kt        # Room database main class
│   ├── converters/                  # Data type converters
│   ├── dao/                         # Data access objects
│   │   ├── PostDao.kt               # Post-related data access
│   │   ├── RecentCategoryDao.kt     # Recent category data access
│   │   └── TagDao.kt                # Tag-related data access
│   └── model/                       # Database entity models
│       ├── post/                    # Post-related entities
│       │   ├── DatabasePost.kt      # Post main entity
│       │   ├── DatabaseCategory.kt  # Category entity
│       │   └── ...(other post entities)
│       ├── savedpost/               # Saved post entities
│       │   ├── SavedPost.kt         # Saved post main entity
│       │   ├── SavedCategory.kt     # Saved post category
│       │   └── ...(other saved post entities)
│       ├── ...(other entities)
│
├── model/                           # Data model classes
│   ├── api/                         # API response models
│   │   ├── comment/                 # Comment API models
│   │   │   ├── Content.kt           # Comment content
│   │   │   └── ResponseComment.kt   # Comment response model
│   │   ├── post/                    # Post API models
│   │   │   ├── NetworkPost.kt       # Network post model
│   │   │   └── ...(other API models)
│   ├── categories/                  # Category-related models
│   │   └── MyCategoriesGridViewItem.kt
│   ├── comment/                     # Comment domain models
│   │   └── Comment.kt               # Comment information
│   └── post/                        # Post domain models
│       ├── Post.kt                  # Post main model
│       ├── Category.kt              # Category model
│       └── ...(other post models)
│
├── network/                         # Network communication classes
│   └── CubadebateApiService.kt      # Retrofit API service interface
│
├── repository/                      # Data repository (Repository pattern)
│   ├── PostRepository.kt            # Post data management
│   ├── RecentCategoryRepository.kt  # Recent category data management
│   └── TagRepository.kt             # Tag data management
│
├── ui/                              # User interface classes
│   ├── CoroutineBaseViewModel.kt    # Coroutine-based base view model
│   ├── PostsViewModel.kt            # Common post view model
│   ├── HeadingsAdapter.kt           # Post list adapter
│   ├── EndlessRecyclerViewScrollListener.kt  # Infinite scroll listener

│   ├── main/                        # Main screen classes
│   │   ├── MainActivity.kt          # Main activity
│   │   ├── MainActivityViewModel.kt # Main activity view model
│   ├── categories/                  # Category screens
│   │   ├── BaseCategoryFragment.kt  # Category base fragment
│   │   ├── HomeFragment.kt          # Home fragment
│   ├── details/                     # Post detail screen
│   ├── comments/                    # Comment-related screens
│   │   ├── CommentsActivity.kt      # Comments activity
│   │   ├── CommentsFragment.kt      # Comments fragment
│   │   ├── RepliesFragment.kt       # Comment replies fragment
│   │   └── ...(ViewModels and other classes)
│   ├── search/                      # Search screens
│   ├── saved/                       # Saved posts screen
│   ├── forme/                       # Personalized recommendation screen
│   │   ├── ForMeFragment.kt         # Recommendation main fragment
│   │   ├── MyCategoriesFragment.kt  # My categories fragment
│   │   ├── MyTopicsFragment.kt      # My topics fragment
│   │   └── ...(ViewModels and other classes)
│   │
│   ├── headingspertag/              # Posts by tag screen
│   ├── subscription/                # Subscription screens
│   └── settings/                    # Settings screens
│       ├── categories/              # Category management
│       └── topics/                  # Topic management
│
└── util/                            # Utility classes and helper functions
    ├── ActivityUtils.kt             # Activity utilities
    ├── BindingUtils.kt              # Data binding utilities
    ├── MappingUtils.kt              # Data mapping utilities
    ├── PostUtils.kt                 # Post utilities
    ├── PreferenceManager.kt         # Settings management utilities
    └── Util.kt                      # General utility functions

🌟 Implementation & Achievements

Built customizable news feed system with dynamic category/topic selection and real-time management by analyzing existing website usage patterns and user feedback
- Implemented real-time topic management system with dynamic search, post count display, and automatic list reordering
- Reduced average content discovery time by 75% (from 2 minutes to 30 seconds)
Implemented robust offline storage for articles and images using Room DB, reducing data usage by up to 30%
Integrated in-article text search, text-to-speech (TTS), and voice recognition features
Implemented real-time article search/filtering, multi-level commenting interface, and infinite scroll, improving user engagement
Built navigation drawer that tracks recently visited categories for easy navigation
Designed Material Design-based UI with smooth animations
Improved accessibility by 40% compared to the website

🧭 Technical Decision-Making

1. Offline Storage Architecture Selection

Requirements
Users needed reliable offline access to news articles even in unstable network environments
Decision
Implemented robust offline storage using Room Database
- Leveraged SQLite’s reliability and Android Jetpack’s type safety for stable data operations with compile-time verification
- Built architecture to store article text, content, and images locally
- Enabled complete offline access to user-selected content through bookmark functionality

@Entity(tableName = "posts")
data class DatabasePost(
    @PrimaryKey val id: Long,
    val title: String,
    val content: String,
    val imageUrl: String?,
    val publishedDate: String,
    val isSaved: Boolean = false
)

2. MVVM Architecture Implementation

Requirements
Needed systematic management of complex news data flows and UI states while efficiently integrating network and local data sources
Decision
Built layered architecture combining MVVM with Repository pattern
- Separation of concerns: Clear responsibility division across View-ViewModel-Repository structure improved code maintainability
- LiveData utilization: Lifecycle-aware observable data prevented memory leaks and ensured automatic UI updates
- Repository pattern: Abstracted network and local database access following Single Source of Truth principle for unified data access logic management

class PostRepository(private val database: CubadebateDatabase) {
    suspend fun getPosts(categoryId: Long?): MutableList<Post> {
        return withContext(Dispatchers.IO) {
            try {
                // Attempt to fetch latest data from network
                val networkPosts = when(categoryId) {
                    null -> CubadebateApi.retrofitService.getPostsAsync()
                    else -> CubadebateApi.retrofitService.getPostsByCategoryAsync(categoryId)
                }.await()
                
                // Save to local DB and return
                networkPosts.map { it.mapToPost() }
            } catch (e: Exception) {
                // Return local data on network failure
                getPostsFromDb(categoryId)
            }
        }
    }
}

🌱 Problem Solving

1. User-Centric Content Discovery Enhancement

Problem
Users found it difficult to freely explore or subscribe to news on topics of interest through the existing website, with no way to customize content based on user preferences
Analysis
- Analyzed website usage patterns and user feedback, identifying that finding specific topic content took an average of over 2 minutes
- Designed an interface enabling users to browse all topics at once with real-time search capabilities
- Implemented intuitive UI showing post counts by topic with selected topics automatically moving to the top
- Developed personalized feed system using RecyclerView and Room Database to aggregate news from user-selected topics
Results
Reduced average content discovery time to 30 seconds, achieving approximately 75% improvement over the website, while significantly enhancing platform usability with personalized content features