Building a Java Bank Account System: A Step-by-Step Guide

Creating a Bank Account System in Java

Explore our comprehensive Java banking system development guide. This guide is designed to provide assistance and help with your Java assignment, offering step-by-step instructions for building a fully functional banking system in Java. Whether you're a student or a programming enthusiast, our resource equips you with the knowledge and skills to excel in Java programming and tackle complex assignments with confidence. Additionally, you'll gain a deep understanding of object-oriented programming principles and design patterns, making it a valuable resource for honing your programming skills.

Block 1: Bank Class

Our banking system begins with the Bank class, which acts as the heart of the operation. It provides a centralized location for managing a variety of accounts, offering several core functionalities:

Add Account: Use the addAccount method to seamlessly integrate new accounts into the bank's system.
Retrieve Account: The getAccount method allows you to retrieve specific account details by providing its unique ID.
Deposit Funds: With the deposit method, you can conveniently add money to any account.
Withdraw Funds: The withdraw method lets you withdraw money from an account while ensuring that all transactions are accurately recorded.
Account List: Retrieve a comprehensive list of all accounts held by the bank.
Interest Calculation: The pass method allows for the systematic passing of interest to all accounts for a specified number of months, making it a crucial component of the banking system.


```java
import java.util.ArrayList;
import java.util.List;
public class Bank {
private List

accounts = new ArrayList<>();
public void addAccount(Account account) {
accounts.add(account);
}
public Account getAccount(int id) {
for (Account account : accounts) {
if (account.getId() == id) {
return account;
}
}
return null;
}
public void deposit(int id, int amount) {
Account account = getAccount(id);
if (account != null) {
account.deposit(amount);
}
}
public void withdraw(int id, int amount) {
Account account = getAccount(id);
if (account != null) {
account.withdraw(amount);
}
}
public List

getAccounts() {
return accounts;
}
public void pass(int months) {
for (int i = 0; i < months; i++) {
for (Account account : accounts) {
account.addInterest(account.calculateInterest());
}
}
}
}
```

The `Bank` class represents a bank and contains a list of `Account` objects. It provides methods to add accounts, retrieve accounts by ID, deposit money, withdraw money, get a list of accounts, and pass interest to accounts.

Block 2: Account Class (Abstract)

The core of our banking system is the Account class, which acts as a blueprint for various account types. This class provides the following essential features:

ID and Balance: Every account is assigned a unique ID and maintains a balance field.
APR (Annual Percentage Rate): The apr field allows the annual interest rate for each account type to be specified.
Transaction History: An internal list records all deposit, withdrawal, and transfer activities.
Deposit and Withdrawal: Using the deposit and withdraw methods, you can add or withdraw funds from an account.
Transfer Funds: The transferTo and transferFrom methods facilitate the transfer of money between accounts.
Interest Calculation: Subclasses must implement the calculateInterest method to calculate interest specific to the account type.
Account Closure: An account is considered closed if its balance falls to zero or below, ensuring proper account management.


```java
import java.util.List;
import java.util.ArrayList;
public abstract class Account {
private int id;
private double balance;
private double apr;
private List

history;
protected Account(int id, double apr) {
this.id = id;
this.apr = apr;
history = new ArrayList<>();
}
public int getId() {
return id;
}
public double getBalance() {
return balance;
}
public void deposit(int amount) {
balance += amount;
history.add("Deposit " + id + " " + amount);
}
public void withdraw(int amount) {
balance -= amount;
history.add("Withdraw " + id + " " + amount);
if (balance < 0) {
balance = 0;
}
}
public void transferTo(int amount, int account) {
balance -= amount;
history.add("Transfer " + id + " " + account + " " + amount);
}
public void transferFrom(int amount, int account) {
balance += amount;
history.add("Transfer " + account + " " + id + " " + amount);
}
public abstract double calculateInterest();
public double getApr() {
return this.apr;
}
public List

getHistory() {
return history;
}
public void addInterest(double interest) {
balance += interest;
}
public boolean isClosed() {
return balance <= 0.0;
}
}
```

The `Account` class is an abstract class that serves as the base for different types of bank accounts (e.g., savings, checking, CD). It contains fields for ID, balance, annual percentage rate (APR), and a history list. The class has methods for depositing, withdrawing, transferring funds, calculating interest (abstract), and managing the account's history.

Block 3: PassValidator Class


```java
public class PassValidator {
public boolean validate(String command) {
String[] tokens = command.toLowerCase().split("\\s+");
if (tokens.length != 2) {
return false;
}
try {
int months = Integer.parseInt(tokens[1]);
if (months < 1 || months > 60) {
throw new IllegalArgumentException();
}
return true;
} catch (Exception e) {
return false;
}
}
}
```

The `PassValidator` class is responsible for validating commands related to passing interest to accounts. It checks if the command format is correct and if the specified number of months is within a valid range (1 to 60 months).

Block 4: CreateAccountValidator Class


```java
public class CreateAccountValidator {
private Bank bank;
public CreateAccountValidator(Bank bank) {
this.bank = bank;
}
public boolean validate(String command) {
try {
String[] tokens = command.split(" ");
if (tokens.length < 2) {
return false;
}
String action = tokens[0].toLowerCase();
if (!action.equals("create")) {
return false;
}
String type = tokens[1].toLowerCase();
if (!type.equals("savings") && !type.equals("checking") && !type.equals("cd")) {
return false;
}
String id = tokens[2];
if (id.length() != 8 || !id.matches("[0-9]{8}")) {
return false;
}
// Check if the account exists
if (bank.getAccount(Integer.valueOf(id)) != null) {
return false;
}
Double apr = Double.parseDouble(tokens[3]);
if (apr < 0 || apr > 10) {
return false;
}
double cdAmount = 0;
if (type.equals("cd")) {
String amount = tokens[4];
cdAmount = Double.parseDouble(amount);
if (cdAmount < 1000 || cdAmount > 10000) {
return false;
}
}
return true;
} catch (Exception e) {
return false;
}
}
}
```

The CreateAccountValidator class is responsible for validating commands associated with the creation of new accounts. It thoroughly checks multiple criteria, including:

Correct command format.
Supported account types (savings, checking, CD).
Valid ID format (eight digits).
Non-existence of an account with the same ID.
APR and CD amount within valid ranges (APR: 0 to 10, CD amount: 1000 to 10000).

Conclusion

By following this guide and understanding the various components of this banking system implementation, you'll gain valuable insights into creating and managing bank accounts within a programming environment. Whether you're working on a homework assignment, aspiring to build your own financial software, or exploring the world of financial applications, this system is a valuable resource to help you master the art of Java programming. With your newfound skills and knowledge, you're well-prepared to embark on exciting projects, streamline financial processes, and contribute to the dynamic world of banking technology. Get ready to build your very own Bank Account Management System and enjoy the journey of coding mastery! Happy coding!

Developing a Bank Account Management System in Java