🏦 Core Banking Back-Office System (Java, JavaFX)

A production-grade core banking back-office application built with Java, featuring both CLI and JavaFX desktop interfaces.

Features • Architecture • Installation • Usage • Testing

📋 Overview

A comprehensive Banking Employee Back-Office System implemented in Java, designed using clean Object-Oriented Programming (OOP) principles and a layered architecture. The system features strong validation, custom exception handling, audit logging, automated testing, CSV export, and a full JavaFX Desktop GUI.

This project simulates how bank employees manage customers, accounts, and transactions through:

Interface	Description
🖥️ CLI Application	Console-based interface for terminal users
🪟 JavaFX Desktop GUI	Modern desktop application with rich UI
🧪 JUnit 5 Test Suite	Comprehensive automated testing
📤 CSV Export System	Transaction history export with multiple modes
🔐 RBAC Security	Role-Based Access Control

⚠️ Scope Notice: This system represents employee-assisted banking operations only. No customer self-service, online banking, or external transfers.

ATS-Friendly Project Description

Core Banking Back-Office System (Java, JavaFX) is a layered enterprise banking application for employee operations, built with Java 17, JavaFX, Maven, and JUnit 5. It implements customer onboarding, account lifecycle management, deposits/withdrawals with business-rule validation, role-based access control (RBAC), audit-ready transaction history, and CSV export workflows. The project demonstrates clean OOP design, custom exception handling, test-driven validation of business logic, and maintainable architecture patterns (Facade, Repository, Singleton, MVC) commonly used in production banking software.

🛠️ Tech Stack

Category	Technology	Version
Language	Java	17 (LTS)
GUI Framework	JavaFX	21.0.2
Build Tool	Maven	3.x
Testing	JUnit Jupiter	5.10.1
Architecture	Layered / MVC	-
Data Storage	PostgreSQL with JDBC	15+
Connection Pool	HikariCP	5.1.0

✨ Features

🔐 Authentication & Authorization

Role	Code	Permissions
Customer Service	`CS`	Create customers, Open accounts
Teller	`TELLER`	Deposit, Withdraw, View transactions
Manager	`MANAGER`	Full system access (all operations)

Employee login with username/password validation
Role-based access control enforced at service layer
Secure session management (login/logout)
Authorization checks on every operation

👤 Customer Management

Create customers with Egyptian National ID validation
Comprehensive National ID validation:
- 14-digit format validation
- Birth date extraction and validation
- Governorate code verification (35 valid codes)
- Century detection (2xxx = 1900s, 3xxx = 2000s)
Prevent duplicate customers (unique National ID)
List customers with account count
Search customers by National ID

💳 Account Management

Account Type	Overdraft	Withdrawal Limit
Savings Account	❌ No	Limited to balance
Current Account	✅ Yes	Configurable limit

16-digit account numbers (system-generated)
Multiple accounts per customer supported
Account numbers masked in display (e.g., XXXXXXXXXXXX3456)
Account validation with custom exceptions

💰 Transaction System

Feature	Description
Deposit	Add funds to any account (no fee)
Withdrawal	Remove funds with 1% fee
Fee Calculation	Real-time fee display in GUI
Balance Validation	Polymorphic rules per account type

Transaction Record (Immutable):

├── Transaction ID (unique)
├── Type (DEPOSIT / WITHDRAWAL)
├── Amount
├── Fee (1% for withdrawals)
├── Total (Amount + Fee)
├── Balance After
├── Timestamp
├── Account Number
└── Audit Trail
    ├── Employee ID
    ├── Employee Name
    └── Employee Role

📤 CSV Export System

Three Export Modes:

Mode	Trigger	File Pattern
By Customer	Filter by National ID	`transactions_customer_{nationalId}.csv`
All Transactions	Show All view	`transactions_all_{timestamp}_by_{employee}.csv`
By Account	Legacy/API	`transactions_account_{accountNumber}.csv`

Export Features:

Incremental export (append-only, no duplicates)
Excel-compatible CSV format
Automatic exports/ directory creation
Timestamp tracking per export key

CSV Format:

AccountNumber,Type,Amount,BalanceAfter,PerformedBy,Role,Timestamp,TransactionId

🇪🇬 Egyptian National ID Validation

The system validates Egyptian National IDs according to official format:

Position:  1  | 2-3 | 4-5 | 6-7 | 8-9  | 10-13 | 14
Content:   C  | YY  | MM  | DD  | GOV  | SEQ   | CHECK

Component	Description
Century (C)	`2` = 1900s, `3` = 2000s
Year (YY)	Birth year (00-99)
Month (MM)	Birth month (01-12)
Day (DD)	Birth day (01-31)
Governorate (GOV)	35 valid codes (01-35)
Sequence (SEQ)	Unique identifier
Check (CHECK)	Validation digit

🏗️ Architecture

┌─────────────────────────────────────────────────────────────┐
│                    PRESENTATION LAYER                       │
├─────────────────────────────┬───────────────────────────────┤
│      CLI (Console)          │       JavaFX (Desktop)        │
│  ┌─────────────────────┐    │    ┌─────────────────────┐    │
│  │ BankEmployeeCLI     │    │    │ MainApp             │    │
│  │ LoginView           │    │    │ LoginController     │    │
│  │ MenuView            │    │    │ DashboardController │    │
│  │ CustomerView        │    │    │ CustomerFormCtrl    │    │
│  │ AccountView         │    │    │ AccountFormCtrl     │    │
│  │ TransactionView     │    │    │ TransactionFormCtrl │    │
│  └─────────────────────┘    │    └─────────────────────┘    │
├─────────────────────────────┴───────────────────────────────┤
│                      SERVICE LAYER                          │
│  ┌─────────────────────────────────────────────────────┐    │
│  │ BankService (Facade + Singleton)                    │    │
│  │ ├── AuthenticationService                           │    │
│  │ ├── AuthorizationService                            │    │
│  │ ├── AccountService                                  │    │
│  │ └── TransactionService                              │    │
│  └─────────────────────────────────────────────────────┘    │
├─────────────────────────────────────────────────────────────┤
│                    REPOSITORY LAYER                         │
│  ┌─────────────────────────────────────────────────────┐    │
│  │CustomerRepository │ AccountRepository │ TxRepository│    │
│  └─────────────────────────────────────────────────────┘    │
├─────────────────────────────────────────────────────────────┤
│                      DOMAIN LAYER                           │
│  ┌─────────────────────────────────────────────────────┐    │
│  │ Person ← Customer, Employee                         │    │
│  │ Account ← SavingsAccount, CurrentAccount            │    │
│  │ Transaction, TransactionType, AccountType           │    │
│  │ EmployeeRole                                        │    │
│  └─────────────────────────────────────────────────────┘    │
├─────────────────────────────────────────────────────────────┤
│                      UTILITY LAYER                          │
│  ┌─────────────────────────────────────────────────────┐    │
│  │ NationalIdValidator │ AccountValidator │ IdGenerator│    │
│  │ NumberFormatter │ TransactionPrinter                │    │
│  └─────────────────────────────────────────────────────┘    │
└─────────────────────────────────────────────────────────────┘

📚 Documentation

Architecture & Design

PostgreSQL JDBC Migration Plan — PostgreSQL_JDBC_Plan.md outlines the transition from in-memory data structures to persistent database storage using JDBC

Database Persistence Layer

Recent Transformation (v2.0.0):

The repository layer has been migrated from in-memory collections to PostgreSQL database persistence with JDBC connectivity:

Component	Previous	Current
CustomerRepository	`HashMap<String, Customer>`	PostgreSQL via JDBC + HikariCP pooling
AccountRepository	`HashMap<String, Account>`	PostgreSQL via JDBC + HikariCP pooling
TransactionRepository	`ArrayList<Transaction>`	PostgreSQL via JDBC + HikariCP pooling

Benefits of Migration:

✅ Data Durability — Customer, account, and transaction records persist across application restarts
✅ Concurrent Access — Multi-session support with proper connection pooling via HikariCP
✅ Database-Level Constraints — Unique key enforcement (National ID, account numbers) at the database layer
✅ Query Flexibility — JDBC enables advanced filtering, pagination, and reporting capabilities
✅ Audit Trail — Transaction history remains intact indefinitely
✅ Backward Compatibility — Public repository interfaces remain unchanged; service layer workflows are unaffected

Database Configuration: Located in com.finance.bank.config.DatabaseConfig:

JDBC URL: jdbc:postgresql://localhost:5432/finance_bank
Connection Pool: HikariCP with max 10 connections, min 2 idle connections
Driver: PostgreSQL JDBC driver
See DatabaseConfig.java for details

Schema Setup: Refer to the PostgreSQL JDBC Plan documentation for DDL scripts and schema initialization.

📌 Documentation Index

PostgreSQL JDBC Plan — Database migration and schema design
REFACTORING.md — Code refactoring notes
Action Plan — Development roadmap

📂 Project Structure

banking-system/
│
├── pom.xml                          # Maven configuration
├── README.md                        # This file
│
├── docs/                            # Documentation
│   └── PostgreSQL_JDBC_Plan.md      # Database migration plan
|  └── REFACTORING.md                # Code refactoring notes
|  └── Action plan.md                # Development roadmap
│
├── exports/                         # CSV export output directory
│   ├── transactions_customer_*.csv
│   └── transactions_all_*.csv
│
├── src/
│   ├── main/
│   │   ├── java/com/finance/bank/
│   │   │   │
│   │   │   ├── app/                 # Entry Points
│   │   │   │   ├── BankEmployeeCLI.java
│   │   │   │   └── MainApp.java
│   │   │   │
│   │   │   ├── model/               # Domain Models
│   │   │   │   ├── Person.java
│   │   │   │   ├── Customer.java
│   │   │   │   ├── Employee.java
│   │   │   │   ├── EmployeeRole.java
│   │   │   │   ├── Account.java
│   │   │   │   ├── SavingsAccount.java
│   │   │   │   ├── CurrentAccount.java
│   │   │   │   ├── AccountType.java
│   │   │   │   ├── Transaction.java
│   │   │   │   └── TransactionType.java
│   │   │   │
│   │   │   ├── repository/          # Data Access Layer
│   │   │   │   ├── CustomerRepository.java
│   │   │   │   ├── AccountRepository.java
│   │   │   │   └── TransactionRepository.java
│   │   │   │
│   │   │   ├── service/             # Business Logic
│   │   │   │   ├── BankService.java
│   │   │   │   ├── AuthenticationService.java
│   │   │   │   ├── AuthorizationService.java
│   │   │   │   ├── AccountService.java
│   │   │   │   └── TransactionService.java
│   │   │   │
│   │   │   ├── exception/           # Custom Exceptions
│   │   │   │   ├── InvalidNationalIdException.java
│   │   │   │   ├── DuplicateNationalIdException.java
│   │   │   │   ├── InvalidAccountException.java
│   │   │   │   ├── DuplicateAccountException.java
│   │   │   │   ├── InvalidAmountException.java
│   │   │   │   ├── InsufficientAmountException.java
│   │   │   │   ├── AuthenticationException.java
│   │   │   │   ├── UnauthorizedException.java
│   │   │   │   ├── AccessDeniedException.java
│   │   │   │   └── ResourceNotFoundException.java
│   │   │   │
│   │   │   ├── util/                # Utilities
│   │   │   │   ├── NationalIdValidator.java
│   │   │   │   ├── AccountValidator.java
│   │   │   │   ├── IdGenerator.java
│   │   │   │   ├── NumberFormatter.java
│   │   │   │   └── TransactionPrinter.java
│   │   │   │
│   │   │   ├── view/                # CLI Views
│   │   │   │   ├── LoginView.java
│   │   │   │   ├── MenuView.java
│   │   │   │   ├── CustomerView.java
│   │   │   │   ├── AccountView.java
│   │   │   │   ├── TransactionView.java
│   │   │   │   └── InputValidator.java
│   │   │   │
│   │   │   └── presentation/        # JavaFX Layer
│   │   │       ├── controllers/
│   │   │       │   ├── LoginController.java
│   │   │       │   ├── DashboardController.java
│   │   │       │   ├── DashboardHomeController.java
│   │   │       │   ├── CustomerFormController.java
│   │   │       │   ├── CustomerListController.java
│   │   │       │   ├── AccountFormController.java
│   │   │       │   ├── AccountListController.java
│   │   │       │   ├── TransactionFormController.java
│   │   │       │   ├── TransactionHistoryController.java
│   │   │       │   └── EmployeeAware.java
│   │   │       └── util/
│   │   │           ├── NavigationManager.java
│   │   │           ├── SessionManager.java
│   │   │           └── AlertHelper.java
│   │   │
│   │   └── resources/com/finance/bank/presentation/
│   │       ├── views/               # FXML Files
│   │       │   ├── login.fxml
│   │       │   ├── dashboard.fxml
│   │       │   ├── dashboard_home.fxml
│   │       │   ├── customer_form.fxml
│   │       │   ├── customer_list.fxml
│   │       │   ├── account_form.fxml
│   │       │   ├── account_list.fxml
│   │       │   ├── transaction_form.fxml
│   │       │   └── transaction_history.fxml
│   │       └── css/
│   │           └── bank-theme.css   # Custom Theme
│   │
│   └── test/java/com/finance/bank/test/
│       └── BankingSystemTest.java   # JUnit 5 Tests
│
└── target/                          # Build output
    └── banking-system-2.0.0.jar

❗ Custom Exceptions

Exception	Scenario
`InvalidNationalIdException`	National ID format/validation failed
`DuplicateNationalIdException`	Customer already exists
`InvalidAccountException`	Account validation failed
`DuplicateAccountException`	Account number already exists
`InvalidAmountException`	Amount ≤ 0 or invalid format
`InsufficientAmountException`	Balance/overdraft limit exceeded
`AuthenticationException`	Login credentials invalid
`UnauthorizedException`	Employee lacks permission
`AccessDeniedException`	Access to resource denied
`ResourceNotFoundException`	Requested resource not found

🧠 Design Patterns

Pattern	Implementation	Purpose
Singleton	`BankService`	Single point of access to business logic
Facade	`BankService`	Simplified API for complex subsystems
Repository	`*Repository` classes	Abstract data storage operations
MVC	JavaFX Controllers + FXML	Separation of concerns in GUI
Strategy	`Account.withdraw()`	Different withdrawal rules per account type
Template Method	`Account` abstract class	Common behavior with customization points
Factory	`IdGenerator`	Centralized ID generation
Observer	JavaFX Property Bindings	Real-time UI updates

🔒 Security Features

Feature	Implementation
Role-Based Access Control	`AuthorizationService` checks on every operation
Immutable Transactions	All `Transaction` fields are `final`
Masked Account Numbers	Display as `XXXXXXXXXXXX3456`
Input Validation	Custom validators for all user input
Exception-Driven Security	Custom exceptions for all error scenarios
Audit Trail	Every transaction records employee details
Session Management	`SessionManager` for secure employee sessions
Defensive Copying	Unmodifiable collections returned from repositories

🪟 JavaFX Desktop Application

Screenshots & Features

🔑 Login Screen

Employee authentication
Role detection and display
Secure session initialization

📊 Dashboard

Role-based navigation sidebar
Dynamic content loading
Employee info display
Quick action buttons

👤 Customer Management

Create customer form with validation
Customer list with search
Account count per customer

💳 Account Management

Open Savings/Current accounts
Configurable overdraft limits
Account list with filtering

💰 Transactions

Deposit/Withdraw forms
Real-time fee calculation
Dynamic fee information card
Transaction receipt display
Transaction history with filters
Export to CSV

UI Components

Custom CSS theme (bank-theme.css)
Responsive sidebar navigation
Alert system for feedback
Form validation with visual feedback
Data tables with sorting
Masked sensitive data display

🖥️ CLI Application

Complete console-based workflow:

┌─────────────────────────────────────────┐
│           FINANCE BANK CLI              │
├─────────────────────────────────────────┤
│  1. Login                               │
│  2. Create Customer                     │
│  3. Open Account                        │
│  4. Deposit                             │
│  5. Withdraw                            │
│  6. Transaction History                 │
│  7. Export CSV                          │
│  8. Logout                              │
│  0. Exit                                │
└─────────────────────────────────────────┘

🧪 Automated Testing

Test Coverage

Category	Tests
Authentication	Login success/failure, invalid credentials
Authorization	Role-based access, permission denied
Customer	Creation, validation, duplicates
Account	Opening, validation, types
Transactions	Deposit, withdraw, fees, overdraft
Exceptions	All custom exception scenarios

Running Tests

# Run all tests
mvn test

# Run with verbose output
mvn test -Dtest=BankingSystemTest

# Run specific test method
mvn test -Dtest=BankingSystemTest#testDeposit

Test Isolation

@BeforeEach
void setUp() {
    BankService.getInstance().reset();  // Clean state for each test
}

🚀 Installation

Prerequisites

Java 17 or higher
Maven 3.x
JavaFX SDK 21 (handled by Maven)

Clone & Build

# Clone repository
git clone https://github.com/omar-abdullah-dev/Core-Banking-Backoffice-Java.git
cd BankSystemWIthExceptions

# Build project
mvn clean install

# Run tests
mvn test

🎮 How to Run

JavaFX Desktop Application (Recommended)

mvn javafx:run

CLI Application

# Using Maven
mvn exec:java -Dexec.mainClass="com.finance.bank.app.BankEmployeeCLI"

# Or run directly from IDE
# Main class: com.finance.bank.app.BankEmployeeCLI

Default Test Credentials

Username	Password	Role
`ahmed`	`ahmedPass!`	Manager
`mohamed`	`mohamedPass!`	Teller
`omar`	`omarPass!`	CS

📊 Example Workflow

1. Login as Manager (ahmed/ahmedPass!)
2. Create Customer (Enter valid Egyptian National ID)
3. Open Savings Account for customer
4. Deposit EGP 10,000
5. Withdraw EGP 1,000 (Fee: EGP 10, Total: EGP 1,010)
6. View Transaction History
7. Export to CSV
8. Logout

📌 Project Status

Component	Status
CLI Application	✅ Complete
JavaFX GUI	✅ Complete
Unit Tests	✅ Complete
CSV Export	✅ Complete
Documentation	✅ Complete
Code Quality	✅ Production-Ready

🔮 Future Improvements

Database Persistence — ✅ Migrated to PostgreSQL with JDBC (v2.0.0) — See PostgreSQL JDBC Plan
Password Hashing — BCrypt encryption for employee credentials
Spring Boot API — RESTful web services for mobile/external clients
Web Frontend — React/Angular customer portal
Microservices — Service decomposition for scalability
Logging Framework — SLF4J + Logback integration
Docker Support — Containerization for deployment
CI/CD Pipeline — GitHub Actions automated builds and tests

📄 License

This project is open-source and intended for educational purposes.

👨‍💻 Author

Omar Abdullah Moharam

Built with ❤️ to demonstrate clean Java architecture, OOP principles, and production-quality code.

Name		Name	Last commit message	Last commit date
Latest commit History 101 Commits
.idea		.idea
docs		docs
exports		exports
src		src
target		target
.gitignore		.gitignore
BankSystemWIthExceptions.iml		BankSystemWIthExceptions.iml
README.md		README.md
core-banking-backoffice-system.iml		core-banking-backoffice-system.iml
pom.xml		pom.xml

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🏦 Core Banking Back-Office System (Java, JavaFX)

📋 Overview

ATS-Friendly Project Description

🛠️ Tech Stack

✨ Features

🔐 Authentication & Authorization

👤 Customer Management

💳 Account Management

💰 Transaction System

📤 CSV Export System

🇪🇬 Egyptian National ID Validation

🏗️ Architecture

📚 Documentation

Architecture & Design

Database Persistence Layer

📌 Documentation Index

📂 Project Structure

❗ Custom Exceptions

🧠 Design Patterns

🔒 Security Features

🪟 JavaFX Desktop Application

Screenshots & Features

UI Components

🖥️ CLI Application

🧪 Automated Testing

Test Coverage

Running Tests

Test Isolation

🚀 Installation

Prerequisites

Clone & Build

🎮 How to Run

JavaFX Desktop Application (Recommended)

CLI Application

Default Test Credentials

📊 Example Workflow

📌 Project Status

🔮 Future Improvements

📄 License

👨‍💻 Author

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