ATM Simulation System

A beginner-friendly and real-world style ATM Simulation System built using Core Java and Object-Oriented Programming (OOP) principles.
This project simulates basic ATM operations such as secure login using Account Number + PIN, balance inquiry, deposit, withdrawal, and PIN change.

---

🚀 Features

• Multiple account support
• Login using Account Number + PIN
• Check account balance
• Deposit money
• Withdraw money
• Change PIN
• Withdrawal limit validation
• Input validation using try-catch
• Beginner-friendly modular code structure

---

🛠️ Technologies Used

• Core Java
• OOP Concepts
• Java Packages
• Exception Handling
• Console-Based Application

---

📂 Project Structure

ATM-Simulation-System/ │ ├── interfaces/ │ └── ATMService.java │ ├── models/ │ ├── BankAccount.java │ └── SavingAccount.java │ ├── services/ │ └── ATMServiceImpl.java │ └── ATMApp.java

---

💡 OOP Concepts Used

1. Abstraction

Used through the ATMService interface.

2. Encapsulation

Used in the BankAccount class with private fields like:

• accountNumber
• balance
• pin

3. Inheritance

SavingAccount extends BankAccount.

4. Polymorphism

ATMService reference is used with ATMServiceImpl object.

Example:

ATMService atm = new ATMServiceImpl(selectedAccount);