Console Applications

Personal Expense Tracker

Build a console application that records income and expenses, organizes transactions by category, calculates the current balance, and displays a financial summary.

Intermediate120 minutes0 features

What you will build

Build a robust CLI expense tracker from scratch that manages finances and persists data to a local file.

Learning objectives

After completing the project, the learner should understand:
Master file I/O operations by reading from and writing structured data to text/CSV files
Design and implement custom data models (classes/structs) to represent real-world entities
Manage application state and dynamic collections (arrays, lists, vectors) in memory
Build a robust, interactive command-line interface with a continuous menu loop
Implement data aggregation algorithms (calculating totals and filtering records by category/date)
Handle edge cases and parse user input safely to prevent application crashes
Apply Object-Oriented Programming (OOP) principles like encapsulation and separation of concerns

Prerequisites

Basic understanding of variables, loops, and conditional statements
Familiarity with creating functions/methods and passing arguments
Basic knowledge of classes/objects (if using an Object-Oriented language)
Understanding of standard console input and output (reading from keyboard, printing to screen)

Core requirements

Project milestones

Create the menu
Create the main menu and repeatedly ask the user to select an option, rejecting invalid inputs and exiting safely.
Design a transaction
Define the information stored for each transaction (ID, Type, Amount, Category, Description, Date) using a Class, Record, Structure, or Object.
Add income and expenses
Create the workflow for entering and validating transaction details (Amount > 0, Category not blank, Valid date format).
Store multiple transactions
Use an appropriate collection (ArrayList, vector, List, Array) to store the transaction objects in memory.
Calculate the summary
Loop through all transactions and calculate total income, total expenses, and current balance using decimal-safe money types.
Group expenses by category
Accumulate expenses separately for each category using a Map or Dictionary.
Add search and deletion
Allow the user to filter by type/category, find by ID, and securely delete a transaction from the list.
Add file persistence
Load existing transactions on startup and save them after a change. Ensure the app doesn't crash if the file is missing.

Sample interaction

========================================
PERSONAL EXPENSE TRACKER
========================================

1. Add income
2. Add expense
3. View all transactions
4. View financial summary
5. View expenses by category
6. Search transactions
7. Delete a transaction
8. Save transactions
9. Exit

Choose an option:

Testing checklist

Add a new expense and verify it immediately appears when viewing the list
Enter an invalid menu option (e.g., '9') and ensure the program doesn't crash
Enter text (like "abc") when the program asks for an expense amount and verify the error is handled gracefully
Close the program entirely, restart it, and verify that previously saved expenses are loaded correctly
View the summary and verify that the math for the total sum is 100% correct
Try deleting an expense ID that doesn't exist and ensure the program handles it properly

Choose an implementation

Build with JavaStarter files and reference solution

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