📥 Downloader (Kotlin + Compose + OkHttp)

A modern Android file downloader built with Kotlin, Jetpack Compose, and OkHttp, featuring real-time progress tracking, clean architecture, and robust error handling.

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screenshot:

🚀 Features

• 📡 Download files from direct URLs (supports large files)
• 📊 Real-time progress tracking (0% → 100%)
• 🧠 Clean architecture (ViewModel + Repository pattern)
• ⚡ Coroutine + Flow-based streaming download
• ❌ Cancel download anytime
• ⚠️ Error handling with sealed classes
• 🎯 Modern UI built with Jetpack Compose (Material 3)
• 💾 Saves files to app-specific storage

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🧱 Tech Stack

• Kotlin
• Jetpack Compose
• AndroidX ViewModel
• Kotlin Coroutines + Flow
• OkHttp
• Material 3

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🏗 Architecture

UI (Jetpack Compose) ↓ ViewModel ↓ Repository ↓ OkHttp Client

Responsibilities:

• ViewModel

  • Manages UI state (progress, status, errors)
  • Handles user actions (start / cancel download)

• Repository

  • Handles network request (OkHttp)
  • Streams file bytes
  • Emits progress via Flow

• Flow

  • Provides real-time updates to UI

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📦 Download Flow

1. User clicks Start Download
2. ViewModel triggers Repository
3. OkHttp starts streaming file
4. File is written to disk chunk by chunk
5. Progress updates are emitted via Flow
6. UI updates instantly

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📊 Download States

sealed class DownloadResult {
    data class Progress(val percent: Float, val code: Int) : DownloadResult()
    object Success : DownloadResult()
    data class Error(val message: String) : DownloadResult()
}
States handled in app:
Downloading 📥
Completed ✅
Cancelled ❌
Failed ⚠️
📸 UI Preview

Add screenshots or GIFs here

Example UI elements:

Progress indicator
Download percentage
File size (MB)
Cancel button
Status badge
📂 Output Location

Downloaded file is saved in:

/Android/data/<package_name>/files/Download/calendar.apk
🧠 Key Concepts Used
Coroutine cancellation with Job
Cold Flow for streaming downloads
File I/O with buffering (ByteArray)
State management with StateFlow
Reactive UI with Jetpack Compose
⚙️ How to Run
1. Clone repository
git clone https://github.com/your-username/repository-name.git
2. Open in Android Studio
Latest stable version recommended
3. Run on emulator or physical device
Minimum SDK: (add your value here)
📌 TODO (Future Improvements)
 Pause / Resume download
 Multi-file downloader
 Background download service
 Notification progress bar
 Retry mechanism with exponential backoff
 Download speed indicator (KB/s, MB/s)
👨‍💻 Author

Ali Mahjoob

Android Developer
Kotlin • Jetpack Compose • Clean Architecture

⭐ Support

If you like this project:

⭐ Give it a star on GitHub
🍴 Fork it and improve it
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