Split Expense System (Java - LLD Project)

This is a Java-based command-line application for managing and tracking shared expenses between users. The system supports adding expenses, calculating split amounts (Equal, Exact, Percent), and viewing net balances. Built using clean object-oriented design and low-level design principles, this project models real-world expense sharing similar to platforms like Splitwise.

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Overview

This project allows users to:

• Create users and assign expenses
• Share expenses using different split types:
  • Equal
  • Exact
  • Percent
• Track how much each user owes or is owed
• View individual or overall balances
• Scale easily with new expense types or group features

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Primary Classes

• User.java
  Represents a user with a unique ID and name.

• Balance.java
  Tracks how much one user owes another.

• Expenses.java
  Represents a single expense, with payer, amount, splits, and type.

• Split.java (Abstract class/interface)
  Base for all split strategies.

• SplitEqual.java, SplitExact.java, SplitPercent.java
  Implement different strategies for splitting expenses.

• SplitType.java
  Enum to represent supported split types: EQUAL, EXACT, PERCENT.

• ExpenseService.java
  Handles the core business logic: adding expenses, calculating balances, managing users.

• SplitExpense.java
  Entry point / main class that reads command-line input and routes to ExpenseService.

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Tech Stack

• Java SE 17+

• Java Collections (Map, List)

• Console-based input

• Modular object-oriented design

Author

• Jeevitha Shree T