What Needs to be Done
Before jumping into writing the code, it’s important to make sure that you are completely clear of the requirements that the application is going to possess. At the heart of any banking software, these operations should be there:
1. Account Creation
When a user wants to create a new account in a bank, this must be provided in the application. For this an account holder’s name, account category (savings or checking) and the amount that will be deposited into the account have to be filled.
2. Depositing Funds
A user should have the ability to put money into the account. In this function, the account balance will automatically change every time the user deposits some funds in order to keep it accurate.
3. Withdrawing Funds
Also, a user should be able to withdraw funds from his/her account. Before permitting the operation to be carried out, it is necessary to check if the account has a sufficient balance in it.
4. Checking Account Balance
The user should be enabled to check the account balance in the system whenever he or she feels like doing so.
5. Transfer Between Accounts
Another feature that a simple banking app may provide is that users may transfer amounts from one account to another, which will require using a number of the accounts at the same time.
Defining the Classes and Objects
In OOP, a class specifies a basic description of an object, its attributes and operations. In the case of banking applications, we may begin by implementing a `BankAccount` class. This class is supposed to implement the bank account, and its properties can include account holder name, account number, and account balance.
The `BankAccount` class will encapsulate all the actions that can be done with money accounts. Methods like `deposit()`, `increaseAmount(…)`, `withdraw()`, `decreaseAmount(…)`, `checkBalance()`, and `viewAccount(…)` would refer to depositing money, taking out some money, seeing how much was available, and so on.
A new class can be called, for instance, `Bank` allowing combining multiple `BankAccount` objects together. This class can also offer opening of new accounts, searching for accounts by numbers and support several operations such as money transfer between the existing accounts.
Implementing Core Functionalities
1. Account Creation:
For opening an account in a bank, the application has to get requisite information from the user. In most cases, the user will give their names, type of the account and how much will be deposited there. Then, with the provided information, the application creates and adds a new `BankAccount` object and assigns a unique number to it. This information can be kept in structures (such as a list or a map) to ensure that all accounts have been accounted for.
2. Depositing Money:
The `deposit()` method will enable the user to put in money in their account. The deposits put in the particular account can change the balance amount of that account as well. However, the input requires validation, that is, the amount which is to be put in as deposit should be a number greater than zero.
3. Withdrawing Money:
The `withdraw()` function grants the ability to withdraw but treats it as a financial transaction first, therefore scanning if there is a sufficient balance in the account. If the account balance is good, then the request gets approved and the record is changed correspondingly. If no funds are available, a message should be displayed indicating that the account has no sufficient funds.
4. Balance in the Account:
In order to know the amount that an account holds, a `checkBalance()` function has been defined which displays a number. This function is very easy to execute because it simply requires looking up the balance kept in the account.
5. Moving The Funds Between Accounts:
Transferring funds from one account to another could be enabled via this transfer feature. The transfer method is mainly composed of checking both accounts: the transferring account for adequate funds, and the receiving account for existence. After verifying that all the conditions are satisfied, the system prompts for deducting the amount from the sender's account, and adding it to the receiver's account.
User Data As An Interface
The need for user data is strong as the application is aimed at the end user, therefore user data management needs to be handled thoughtfully. Generally in this category, a user of the application will be prompted to provide information such as their name, account number, how much they would like to deposit and how much they would like to withdraw.
In a banking simulation, a user can work with the application using the command line while a mouse stays idle. The Java programming language has a `Scanner` class that allows reading data entered in the console. For instance, you can ask the user to give you their account number and fetch the input using `nextInt()` or `nextLine()` methods.
Error Handling and Validation
As in every application, the issue of handling errors is also important in the banking application. Invalid outputs or potentially illegal operations offers have to be checked and properly managed. For instance, a negative number should never be used as a transfer or withdrawal amount and the funds transferred must not be greater than what is available to the sender in his account.
Then, it is crucial to address also such situations when a user tries to do operations that require funds from an unrelated account or accepts other illicit actions such as withdrawing cash in excess of the balance. These mistakes are also accompanied by user-friendly messages that provide the necessary information to the user.
UI for Simple Banking Application
We can design the UI for this simple banking application in a very basic form. If you are designing for a console, perhaps a better approach would be to design a menu system that lets the end user select the operations to be performed. The application could show the following form:
- Register new bank account
- Put in some funds
- Take out some cash
- Send some funds
- Check how much cash is left in
- Leave the application.
The user clicks on a radio button, and the application calls the method that corresponds to the radio button that has been selected. If you want to work more, you may later focus on how to design a GUI with JavaFX or Swing that allows you to design forms, buttons and textboxes for better interaction.
For Typical Banking Application
In normal applications, information is maintained in a database so that the users and their transaction details are not lost after the session ends. But for this simple banking application, it is alright to use some of the built-in structures in Java like arrays, lists or maps to hold the account details during the session.
It is possible to save the accounts on a Map as follows: the key is the account number and the value is the `BankAccount` object. This way you can easily access the accounts and request actions on them.
Security
As simple as this might be a banking application, it is crucial to mention security practices during the design of such a system. While this may be too intricate for the current version of the system, one would want to implement measures to ensure that users' information is not exposed and that the passwords are well secured.
For this minimal demo version of the application, you may want to pretend that there is security such that the user first has to enter their account number correctly and then pass an identity verification procedure (e.g., a pin or a password) before they access actions such as withdrawal of funds or transfer of funds.
