Daehan Lim

Gas Consumption Manager

📝 Overview

📌 App Introduction: Android application automating manual gas usage management for Cuba’s national Manufactured Gas Company
🕒 Duration: February 20, 2021 ~ March 18, 2021 (1 month)
📱 Platform: Native Android app
🏢 Company: Desoft (Cuba’s national software development company)
👥 Team Size: 1 developer
💼 Role: Full Android app development
🛠️ Key Technologies: Android Kotlin Coroutines MVVM Room VideoView Jetpack Material Design Data Binding Navigation MPAndroidChart
🔗 GitHub: daehan-lim/gas-consumption-manager

📖 Project Background

Cuba’s national Manufactured Gas Company faced operational inefficiencies due to their manual gas consumption recording and billing calculation. All procedures from gas meter readings to billing calculations required manual work, leading to time-intensive operations and increased risk of calculation errors. Additionally, customers lacked systematic educational resources for gas meter reading methods and had limited access to customer support. This project developed a comprehensive mobile solution to automate usage calculations, provide educational resources through a video guide, and implement offline-first design for reliable operation.

📋 Project Structure

├── features/                           # Feature-based modular structure
│   ├── consumption/                    # Gas consumption calculation feature
│   │   ├── ConsumptionFragment.kt      # Consumption input and calculation UI
│   │   ├── ConsumptionViewModel.kt     # Consumption calculation business logic
│   │   └── ConsumptionViewModelFactory.kt
│   ├── history/                        # Usage history and chart analytics
│   │   ├── HistoryActivity.kt          # Chart-based analysis screen
│   │   ├── HistoryViewModel.kt         # Chart data processing logic
│   │   └── HistoryViewModelFactory.kt
│   ├── offices/                        # Branch office contact directory
│   │   ├── ComercialOfficesFragment.kt # Branch office list UI
│   │   ├── ComercialOfficesAdapter.kt  # RecyclerView adapter
│   │   └── ComercialOfficesViewModel.kt
│   ├── readcounter/                    # Meter reading guide
│   │   ├── ReadCounterFragment.kt      # Video guide screen
│   │   └── ReadCounterViewModel.kt
│   ├── about/                          # App information and contacts
│   │   └── AboutActivity.kt
│   └── splash/                         # Splash screen
│       └── SplashActivity.kt
├── database/                           # Room database layer
│   ├── Consumption.kt                  # Consumption data entity
│   ├── ConsumptionDao.kt               # Data access object
│   └── ConsumptionDatabase.kt          # Database configuration
├── model/                              # Data models
│   └── ComercialOffice.kt              # Branch office information model
├── util/                               # Utility classes
│   ├── BindingUtils.kt                 # Data binding adapters
│   └── Util.kt                         # Common utility functions
└── MainActivity.kt                     # Main activity and navigation

🌟 Implementation Details

Room Database-based Offline Data Management and Storage

Implemented MVVM architecture with Repository pattern
- Created data access layer abstraction through ConsumptionDao to separate business logic
- Used Coroutines and suspend functions for asynchronous database operations, preventing UI thread blocking
- Built reactive UI with LiveData and ViewModel for lifecycle-aware data binding
- Applied Singleton pattern with fallbackToDestructiveMigration() for stable database management
Implemented Efficient Data CRUD Operations
- Implemented monthly consumption retrieval, yearly data filtering, and automatic integration of latest meter readings
- Ensured data continuity by automatically loading previous month’s meter readings

Automated Gas Usage Calculation with Real-Time Validation

Real-time Input Validation and Error Prevention
- Implemented immediate error alerts and input blocking when current meter readings are lower than previous readings
- Created real-time field validation UI using TextInputLayout’s errorEnabled property
- Provided instant feedback for missing required fields, minimizing user input errors
Developed automated billing calculation system
- Implemented consistent fee calculation using PAYMENT_COEFFICIENT constant (2.5)
- Enabled immediate result verification through real-time conversion between gas usage (㎥) and fees (pesos)
- Presented calculation results through formatted HTML display and AlertDialog interface

Interactive Data Visualization Using MPAndroidChart

Built annual and monthly consumption analysis charts
- Implemented BarChart visualization for monthly gas consumption patterns with animation effects, enhancing user experience
- Added peso/㎥ unit conversion filtering for multi-perspective data analysis
Created responsive chart interface
- Implemented responsive chart design that adapts to device orientation with optimized label spacing
- Integrated MonthPickerDialog for intuitive year selection interface

VideoView-based Educational Video Guide

Developed full-screen video player for meter reading tutorial
- Customized MediaController with full-screen button and screen rotation controls
- Implemented immersive viewing experience with automatic SystemUI hiding during orientation changes
- Built video playback position saving and restoration for uninterrupted user experience
Lifecycle-aware Media Management
- Prevented memory leaks through proper video resource management across onStart(), onStop(), and onPause() lifecycle events
- Added automatic portrait mode restoration and placeholder screen display when video completes
- Used raw resources for offline video playback, eliminating network dependencies

Customer Support Directory with Direct Communication

Built branch office contact directory
- Integrated contact information to streamline customer inquiry processes
- Implemented direct calling functionality using Intent.ACTION_CALL and SMS via Intent.ACTION_SENDTO
- Added dynamic CALL_PHONE permission handling with fallback to dialer app when permission is denied
- Built reusable view binding logic using @BindingAdapter

User Experience Optimization & Accessibility Improvements

Built Bottom Navigation with Fragment-based screen transitions
- Automated navigation state management using setupWithNavController()
- Added exit confirmation dialog through onBackPressed() override
Designed consistent Toolbar-based action bar
- Included option menus for quick access to features like History and About
Applied custom typography using segoe_ui and seguisb fonts for distinctive branding
Designed splash screen with company logo and brand colors
Integrated social media platform links for Facebook, Instagram, Twitter, Telegram, LinkedIn
Enabled access to external resources through browser integration with Intent.ACTION_VIEW

Development Best Practices and Code Quality

Applied Data Binding and ViewBinding
- Ensured type safety between XML layouts and Kotlin code while eliminating findViewById() calls
- Implemented declarative UI updates using @{viewModel.property} syntax
- Used executePendingBindings() for immediate binding processing to prevent UI flickering

🚀 Results and Impact

70% reduction in operational times: Significantly reduced gas company’s operational times through transition from manual to automated gas billing calculations
Offline-first design: All core features operate without network connectivity through Room local database
Enhanced user satisfaction: Video tutorials and intuitive UI/UX improved meter reading comprehension
Streamlined customer support: Integrated branch office contacts simplified customer inquiry handling and improved accessibility