🏦 Banking System (OOPs Project in Java)

A console-based banking system built using Object-Oriented Programming (OOP) principles in Java.
This project simulates basic banking operations such as creating accounts, depositing money, withdrawing money, viewing balance, and viewing transaction history — with proper exception handling and clean separation of concerns.

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🚀 Features

• Create a new bank account
• Deposit money
• Withdraw money (with rules)
• View account balance
• View transaction history
• Robust exception handling
• Uses cents instead of floating-point values for money accuracy

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🧠 OOP Concepts Used

• Encapsulation

  • Account data (balance, account number) is private and accessed via methods.

• Abstraction

  • Business rules are handled by the service layer.

• Separation of Concerns

  • model → domain objects
  • service → business logic
  • Main → user interaction

• Exception Handling

  • Custom and built-in runtime exceptions are used for rule violations.

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📂 Project Structure

com.bank com.bank ├── Main.java

├── exception

│ ├── AccountNotFoundException.java

│ ├── InsufficientBalanceException.java

│ └── InvalidAmountException.java

├── model

│ ├── Account.java

│ └── Transaction.java

└── service

| └── BankService.java

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⚠️ Business Rules Implemented

• Deposit amount must be positive
• Withdraw amount must be:
  • Positive
  • Less than the maximum withdraw limit
  • Leave at least minimum balance in the account
• Account must exist for any operation

Violations of these rules throw runtime exceptions.

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❗ Exception Handling Design

• Service Layer

  • Throws exceptions when rules are violated
  • Does not print messages

• Main Class

  • Catches exceptions
  • Displays user-friendly messages

Example:

try {
    service.deposit(accNo, amount);
    System.out.println("Deposit successful!");
} catch (RuntimeException e) {
    System.out.println(e.getMessage());
}