SaveTo

SaveTo is a lightweight, single-purpose Android utility that integrates into the system-wide sharing sheet to save shared files, multiple documents, or text directly to any destination chosen via the Storage Access Framework (SAF).

  

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Visual Preview

1. Share Sheet Integration	2. Save Location Selection

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Key Features

• Seamless Share Target: Integrates directly with Android's system share sheet, registering for android.intent.action.SEND and android.intent.action.SEND_MULTIPLE across all MIME types (*/*).
• No Launcher Clutter: The application does not declare a launcher activity, keeping the launcher interface clean. It is active only when files are shared.
• Privacy & Security First: Zero dangerous storage permissions (such as READ_EXTERNAL_STORAGE or WRITE_EXTERNAL_STORAGE) are required. It relies entirely on temporary URI permissions granted dynamically via incoming Intents.
• Bulk Save support: When multiple files are shared, it lets you select a destination directory and saves all files in one operation with a progress tracking indicator.
• Text-to-File Conversion: Automatically detects shared text content, converts it into a .txt file, and prompts to save it.
• Robust Error Handling: Safely reports partial failures when bulk-saving multiple files, handles I/O exceptions, and cleans up temporary cache files.

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🛠️ Developer & Build Guide

Technical Architecture

The codebase is structured following clean Android architecture principles, utilizing Kotlin, Coroutines, and Android Jetpack Architecture Components.

graph TD
    Intent[Incoming Share Intent] --> |SEND / SEND_MULTIPLE| Activity[ShareActivity]
    Activity --> |Resolve Metadata| VM[SaveViewModel]
    Activity --> |Launch Picker| SAF[Storage Access Framework]
    SAF --> |Dest URI| VM
    VM --> |Coroutines IO Dispatcher| Save[Buffered Stream Write]

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Components

• AndroidManifest.xml: Configures the intent filters, theme settings, and application metadata. ShareActivity is configured with a translucent theme (Theme.Translucent.NoTitleBar) so that it overlays seamlessly onto the system share dialog.
• ShareActivity.kt: Manages UI, checks URI read access, interacts with the Android Storage Access Framework (using ActivityResultContracts.CreateDocument and OpenDocumentTree), and shows standard system alerts and progress dialogs.
• SaveViewModel.kt: Houses the business logic for resolving source file details, performing high-performance I/O operations using a buffered stream (8KB buffer size), managing state, and cleaning up cache files.
• strings.xml: Declares all UI string resources and error messages for user-facing localization.

Development & Build Requirements

• SDK Targets: Min SDK 23 (Android 6.0), Target SDK 35 (Android 15)
• Java Compatibility: JDK 17 toolchain
• Build Tool: Gradle Kotlin DSL

Code Styling and Design

This application strictly follows modern development standards:

• Coroutines for Asynchronous I/O: Offloads stream writing tasks to Dispatchers.IO and uses ensureActive() inside loops to respect lifecycle cancellation.
• No Force Unwraps: Handles null values gracefully and relies on defensive typing contracts to prevent runtime crashes.
• Resource Cleanup: Employs use { ... } blocks for Kotlin Closeable objects, ensuring input and output streams are safely closed under all circumstances.

Building the Project

Ensure you have a valid keystore.properties file configured in the root directory prior to building. Run the following command from the project root to compile a release build:

./gradlew assembleRelease