🚀 Comprehensive CLI Application with Quarkus & Picocli

This project demonstrates a powerful command-line interface built with **Qua### **Standard JAR Package** The application can be packaged using:

$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn package

This produces the quarkus-run.jar file in the target/quarkus-app/ directory. Dependencies are copied into the target/quarkus-app/lib/ directory.

Run with: java -jar target/quarkus-app/quarkus-run.jar [command] [options]

Uber JAR Package

To build an über-jar with all dependencies included:

$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn package -Dquarkus.package.jar.type=uber-jar

Run with: java -jar target/*-runner.jar [command] [options]onic Subatomic Java Framework) and Picocli (a modern framework for building feature-rich command line applications).

🎯 Application Overview

A multi-command CLI application showcasing various enterprise patterns:

• Multi-command architecture with organized subcommands
• Rich option support including enums, required parameters, and boolean flags
• Multiple output formats (JSON, CSV, Table)
• Interactive features with progress indicators and styled output
• Comprehensive help system with automatic documentation

📋 Available Commands

1. Greet Command - Interactive greeting with styling options

java -jar target/quarkus-app/quarkus-run.jar greet Alice --style WOW --timestamp

Features:

• Style options: NORMAL, EXCITED, WOW
• Optional timestamp display
• Personalized messaging

2. User Management - CRUD operations with multiple output formats

# List users in different formats
java -jar target/quarkus-app/quarkus-run.jar user list --format JSON
java -jar target/quarkus-app/quarkus-run.jar user list --format CSV
java -jar target/quarkus-app/quarkus-run.jar user list --format TABLE

# Create new user
java -jar target/quarkus-app/quarkus-run.jar user create johndoe --email john@example.com --role ADMIN

# Delete user
java -jar target/quarkus-app/quarkus-run.jar user delete alice

Features:

• Multiple output formats (JSON/CSV/Table)
• Role-based user creation (USER, ADMIN, MODERATOR)
• Simulated database operations

3. File Operations - File processing and management tools

# Analyze file contents
java -jar target/quarkus-app/quarkus-run.jar file analyze document.txt --lines --words --chars

# Process files with operations
java -jar target/quarkus-app/quarkus-run.jar file process --input data.csv --operation TRANSFORM --output result.csv

# Backup multiple files
java -jar target/quarkus-app/quarkus-run.jar file backup "file1.txt" "file2.txt" "config.json" -d "C:\backups"

Features:

• File analysis with statistics
• Processing pipeline with operations: COPY, MOVE, TRANSFORM, COMPRESS, DECOMPRESS, ENCRYPT, DECRYPT
• Batch backup operations with progress indicators

4. System Information - System monitoring and diagnostics

# Show system information
java -jar target/quarkus-app/quarkus-run.jar system --info

# Display memory usage
java -jar target/quarkus-app/quarkus-run.jar system --memory

# Show system properties
java -jar target/quarkus-app/quarkus-run.jar system --properties

# Combine multiple options
java -jar target/quarkus-app/quarkus-run.jar system --info --memory --properties

Features:

• OS and Java version information
• Real-time memory usage monitoring
• System properties inspection

🏗️ Architecture Patterns Demonstrated

Command Structure

• Top-level command with @TopCommand annotation
• Subcommands organized by functional domain
• Nested subcommands for complex operations
• Help integration with automatic documentation

Option Types

• Boolean flags (--verbose, --timestamp)
• Required options (--input, --email)
• Optional parameters with defaults
• Enum choices for controlled input
• Multi-value parameters for file lists

Output Formatting

• Structured data with JSON/CSV export
• Tabular display with aligned columns
• Progress indicators for long operations
• Styled output with emojis and colors
• Error handling with user-friendly messages

If you want to learn more about Quarkus, please visit its website: https://quarkus.io/.

🚀 Running the Application

Development Mode (Hot Reloading)

For development with live coding enabled:

# Use regular Maven (recommended)
$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn quarkus:dev

# Or use Maven wrapper (may have Java version conflicts)
./mvnw quarkus:dev

NOTE: Quarkus ships with a Dev UI available in dev mode at http://localhost:8080/q/dev/

Running with Arguments in Dev Mode

Pass CLI arguments during development:

mvn quarkus:dev -Dquarkus.args='greet Alice --style WOW'
mvn quarkus:dev -Dquarkus.args='user list --format JSON'

Production Build & Run

Build and run the optimized application:

# Build the application
$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn package -DskipTests

# Run the CLI application
java -jar target/quarkus-app/quarkus-run.jar [command] [options]

# Show all available commands
java -jar target/quarkus-app/quarkus-run.jar --help

📦 Building Different Package Types

The application can be packaged using:

./mvnw package

It produces the quarkus-run.jar file in the target/quarkus-app/ directory. Be aware that it’s not an über-jar as the dependencies are copied into the target/quarkus-app/lib/ directory.

The application is now runnable using java -jar target/quarkus-app/quarkus-run.jar.

If you want to build an über-jar, execute the following command:

./mvnw package -Dquarkus.package.jar.type=uber-jar

The application, packaged as an über-jar, is now runnable using java -jar target/*-runner.jar.

⚡ Native Executable (GraalVM)

With GraalVM Installed

Create a native executable for ultra-fast startup:

$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn package -Dnative

Using Container Build

Build native executable without local GraalVM installation:

$env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn package -Dnative -Dquarkus.native.container-build=true

Execute native binary: ./target/code-with-quarkus-1.0.0-SNAPSHOT-runner [command] [options]

🛠️ Troubleshooting

Java Version Issues

If you encounter dependency injection errors:

• Ensure Java 21 is installed and JAVA_HOME is set correctly
• Use regular Maven instead of Maven wrapper for better compatibility:

  $env:JAVA_HOME = "C:\Program Files\Java\jdk-21"; mvn [command]

Common Issues

• Maven wrapper conflicts: Use mvn instead of ./mvnw
• Plugin compatibility: Ensure Quarkus version matches plugin versions
• Native build requirements: GraalVM or Docker required for native builds

💡 Extension Ideas

This CLI application can be extended with:

• Configuration Management - Load/save settings from YAML/JSON files
• Database Integration - JPA entities with H2/PostgreSQL persistence
• REST API Client - Commands for calling external services
• Workflow Automation - Multi-step process orchestration
• Plugin System - Dynamically loadable command modules
• Interactive Mode - REPL-style command interface
• Scheduled Tasks - Cron-like job execution
• Report Generation - PDF/Excel export capabilities

📚 Technical Stack

• Quarkus 3.8.6 - Supersonic Subatomic Java Framework
• Picocli 4.7.6 - Modern CLI framework with rich features
• Jakarta CDI - Dependency injection and context management
• Java 21 - Latest LTS version with modern language features
• Maven 3.9.6 - Build automation and dependency management

📖 Related Guides

• Quarkus Picocli Guide - Develop command line applications with Picocli
• Quarkus Maven Tooling - Learn about building native executables
• Picocli Documentation - Comprehensive Picocli framework documentation

🎯 Example Usage Scenarios

Data Processing Pipeline

# Process and transform data files
java -jar target/quarkus-app/quarkus-run.jar file process --input raw-data.csv --operation TRANSFORM --output clean-data.csv

# Analyze results
java -jar target/quarkus-app/quarkus-run.jar file analyze clean-data.csv --lines --words --chars

User Management Workflow

# Create multiple users
java -jar target/quarkus-app/quarkus-run.jar user create admin --email admin@company.com --role ADMIN
java -jar target/quarkus-app/quarkus-run.jar user create manager --email manager@company.com --role MODERATOR

# Export user list
java -jar target/quarkus-app/quarkus-run.jar user list --format JSON > users-backup.json

System Monitoring

# Quick system check
java -jar target/quarkus-app/quarkus-run.jar system --info --memory

# Detailed diagnostics
java -jar target/quarkus-app/quarkus-run.jar system --info --memory --properties

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Built with ❤️ using Quarkus and Picocli