QQ Farm is a simplified multiplayer farming game implemented using Java Socket Programming, Multithreading, and JavaFX. Each player owns a 4×4 farm grid where they can plant crops, harvest them, and steal from other players' farms. The project focuses on concurrent programming, thread safety, and synchronization among multiple clients connected to a common server.

• Planting: Spend 5 coins to plant crops that mature in 10 seconds
• Harvesting: Collect 12 coins when crops are ripe
• Stealing: Steal up to 25% of yield from other players' ripe crops (only when they're away)
• Farm Visiting: Visit friends' farms to view their progress and potentially steal

• Multi-threaded Server: Handles multiple concurrent clients
• Real-time Synchronization: All clients see updates instantly
• Crash Recovery: Server persists farm states and recovers after crashes
• Disk Persistence: Farm states are saved to disk, enabling recovery across server restarts, going beyond basic in-memory management.
• Thread-safe Operations: Atomic plant/harvest/steal operations prevent race conditions
• Graceful Error Handling: Network failures handled without UI crashes

• java JDK: openjdk-22 (Oracle OpenJDK 22.0.2)
• javafx-fxml: 22.0.1
• javafx-controls: 22.0.1
• maven: 3.8.5
• Socket Programming for client-server communication
• Multithreading with ExecutorService and ScheduledExecutorService
• File I/O for persistent game state
• CSS Styling for modern UI

src/main/java/org/example/demo/
├── Application.java # JavaFX application entry point
├── Controller.java # GUI controller and network handler
├── Game.java # Farm state management
├── Server.java # Multi-threaded game server
├── StealBot.java # Concurrency testing bot
src/main/resources/org/example/demo/
├── board.fxml # GUI layout definition
└── styles.css # UI styling

• Java 17 or higher
• JavaFX SDK configured

• In IntelliJ, run the Server.java file

• In IntelliJ, run the Application.java file for each client
• Make sure to allow multiple instances:
  • Go to Run > Modify Run Configurations...
  • Select the configuration for Application.java
  • Click Modify options > Allow multiple instances

• Enter a unique player name
• Click plots to select them
• Use Plant/Harvest/Steal buttons
• Visit friends by entering their name

• plant <row> <col>
• harvest <row> <col>
• steal <targetPlayer> <row> <col>
• visit <friendName>
• back
• resync

• planted <row> <col> <newCoins>
• harvested <row> <col> <amountEarned> <newCoins>
• stole <amount> <newCoins>
• stolen <row> <col> <amount>
• mature <row> <col>
• visit <friendName> <coins> <farmState>
• view_update <owner> <row> <col> <state> <yield>

• Client Handler Threads: Fixed thread pool (10 threads) for network I/O
• Growth Scheduler: Separate thread pool for crop maturation timers
• JavaFX Thread: Dedicated UI thread with Platform.runLater() for updates

• Each player's Game object is synchronized during critical operations
• Stealing uses victim-first locking to prevent deadlocks
• Atomic yield deduction ensures no over-stealing

• All farm operations are thread-safe with synchronized blocks
• Real-time state synchronization via view_update broadcasts
• Persistent storage with automatic crash recovery

• Graceful disconnect detection
• Automatic reconnection with state resynchronization
• UI remains responsive during network outages

• Farm states persisted to disk every operation
• Growth timers resume after server restart
• Clients automatically reconnect and resync

• Server detects disconnections and releases resources
• Farm state preserved for returning players
• Visitors automatically returned to their farms

• StealBot for Concurrency Testing

• Multiple crop types with different costs/growth times
• Friend lists and gift systems
• Crop market with dynamic pricing
• Mobile client using the same protocol
• Database backend for scalability
• Anti-theft items and protection systems

• JavaFX not found: Ensure JavaFX SDK path is correct
• Port in use: Kill existing Java processes or change port
• Connection refused: Verify server is running
• Name already taken: Choose unique player names

• Check server logs for thread activity and lock acquisition
• Monitor client console for network errors
• Verify farm files in farms/ directory for persistence

• Concurrency Stress Test Procedure: For the concurrency stress test demo, please refer to concurrency_test_procedure.md.
• Failure Recovery Demonstration: For the failure recovery demonstration, please refer to failure_recovery_demo.md.

If you have any questions or need further assistance, feel free to contact me [email protected] :)