PDF Meta Viewer — Android

An Android application that extracts and exports metadata from PDF documents using Apache Tika, serializes the results to JSON via Jackson, and presents them through a clean MVVM-architected UI.

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Features

• Parse any PDF file and extract all embedded metadata (author, title, creation date, content type, and more)
• Optionally include the full document text content alongside the metadata
• Export results as a structured JSON file to a configurable output path
• Clean bottom-navigation UI with three tabs (Home, Dashboard, Notifications)
• Reactive UI powered by LiveData — no manual view refreshes required

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Architecture

MVVM + Repository pattern with Android Navigation Component (single-activity, multi-fragment).

com.example.pdfmetaviewerandroid
├── MainActivity                  # Single activity — hosts NavController + BottomNavigationView
├── ui/
│   ├── home/                     # HomeFragment + HomeViewModel (primary PDF interaction)
│   ├── dashboard/                # DashboardFragment + DashboardViewModel
│   └── notifications/            # NotificationsFragment + NotificationsViewModel
├── extractor/
│   └── PDFExtractor              # Apache Tika integration — parses PDF, returns metadata Map
├── repository/
│   ├── DocumentRepository        # Coordinates extraction and writes JSON to disk
│   └── DocumentRecord            # Data model: id, metadata map, document text
├── converters/
│   └── ConvertJavaMapToJson      # Jackson-based Map → JSON string conversion
└── utilities/
    └── PdfMetaViewerConstants    # File paths and UI state strings

Data flow:

Fragment → ViewModel (LiveData) → DocumentRepository → PDFExtractor (Tika) → JSON file (Jackson)

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Tech Stack

Library	Version	Purpose
Apache Tika Core	2.8.0	PDF parsing engine
Apache Tika Parsers Standard	2.8.0	Full format parser package
Apache Tika XMP	2.8.0	XMP metadata support
Jackson Databind	2.15.2	Map-to-JSON serialization
SLF4J	2.0.9	Logging facade (required by Tika)
log4j-to-slf4j	2.21.0	Logging bridge
AndroidX Navigation	—	Fragment navigation
AndroidX Lifecycle / LiveData / ViewModel	—	MVVM components
View Binding	—	Type-safe view access

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Requirements

• Android SDK: Min API 28 (Android 9.0 Pie), Target/Compile SDK 34
• Java: Source and target compatibility Java 8
• Android Studio: Hedgehog (2023.1.1) or newer recommended

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Getting Started

Clone the repository

git clone https://github.com/your-username/PdfMetaViewerAndroid.git
cd PdfMetaViewerAndroid

Build and run

Open the project in Android Studio and run on a device or emulator (API 28+), or use Gradle from the command line:

# Build debug APK
./gradlew assembleDebug

# Build release APK
./gradlew assembleRelease

# Clean build
./gradlew clean assembleDebug

The debug APK is output to app/build/outputs/apk/debug/.

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Usage

1. Place a PDF file at the path defined by PdfMetaViewerConstants.RESOURCES_EXAMPLE_PATH
   (default: src/main/res/Amazon-S3-Tutorial.pdf).
2. Run the app and navigate to the Home tab.
3. Metadata is extracted and written as JSON to the path defined by PdfMetaViewerConstants.RESOURCES_PATH
   (default: src/main/res/metadata.json).
4. To include the full document text in the output, pass isContentIncluded = true when calling
   PDFExtractor.storeDocumentRecordAs(...).

Output format (example)

{
  "Content-Type": "application/pdf",
  "Author": "Amazon Web Services",
  "Creation-Date": "2021-06-15T10:30:00Z",
  "dc:title": "Amazon S3 Tutorial",
  "pdf:PDFVersion": "1.5",
  "xmpTPg:NPages": "42"
}

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Testing

# Run unit tests (JVM — no device needed)
./gradlew test

# Run a single test class
./gradlew test --tests "com.example.pdfmetaviewerandroid.ExampleUnitTest"

# Run instrumented tests (requires connected device or emulator)
./gradlew connectedAndroidTest

# Run lint checks
./gradlew lint

Test dependencies: TestNG 7.8.0, AssertJ 3.24.2, Mockito 5.8.0, Espresso 3.5.1.

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Project Structure (files)

PdfMetaViewerAndroid/
├── app/
│   ├── src/
│   │   ├── main/
│   │   │   ├── java/com/example/pdfmetaviewerandroid/
│   │   │   ├── res/
│   │   │   │   ├── layout/          # Fragment and activity layouts
│   │   │   │   ├── navigation/      # Navigation graph
│   │   │   │   ├── menu/            # Bottom navigation menu
│   │   │   │   └── values/          # Colors, strings, themes
│   │   │   └── AndroidManifest.xml
│   │   ├── test/                    # Unit tests
│   │   └── androidTest/             # Instrumented tests
│   └── build.gradle.kts
├── build.gradle.kts
├── settings.gradle.kts
└── README.md

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License

This project is provided for educational and demonstration purposes.