What is IOU?

A desktop application that helps two people keep track of money owed to each other. It would typically be useful to a couple, roommates, or any two people that incur shared expenses and/or lend money to each other. IOU keeps a record of all transactions and calculates the current balance (shown in red below).

Should I use it?

Probably not. This project is not actively maintained, and there are web-based solutions to this problem that are far superior, e.g. Spliit or Splitwise.

If you have the technical skills to get IOU up-and-running, and don't mind these drawbacks:

• It can only be accessed via the same desktop/laptop it's installed on
• The only client (user interface) is an ugly desktop application
• It can only track money owed between two people

then go right ahead, but I wouldn't particularly recommend it.

How does it work?

IOU supports two types of transactions: payments and expenses.

Expenses

Shared expenses are recorded in the right-hand table. It is assumed that all shared expenses should be split 50/50. For example, if Ann and Bob have a current balance of $0 (neither owes the other anything), then they receive a gas bill for $100 of which Ann pays $20 and Bob pays $80. This expense should be entered like so:

After this expense is saved, the current balance will indicate that Ann owes Bob $30.

Payments

A payment occurs when one party gives money directly to the other. Typically, a payment will either be a loan or repayment of an outstanding debt. For example, following payment of the gas bill mentioned above, Ann owes Bob $30. Ann repays this debt by giving Bob $30. This should be entered as a payment like so:

After this payment is saved, the current balance will indicate that neither Ann nor Bob owes the other anything.

Archive

By default, all payments and expenses entered since the beginning of time are displayed by IOU. When an archive is performed all payments and expenses that were entered prior to the archive are permanently hidden, but the current balance is carried forward. In other words, an archive clears the list of payments and expenses shown in IOU without affecting the current balance.

Installation

Prerequisites

If using macOS or Linux it is recommended to use either Homebrew or SDKMAN to install the following dependencies.

• Java, version 17 and above.
  • Running the application from source requires a full Java Development Kit (JDK)
  • Running the executable JAR requires only a Java Runtime Environment (JRE)
• MySQL, version 8 and above
• Maven, version 3

Configuration

The steps below only need to be performed once, before you run the application for the first time:

• Create a MySQL database named iou. If the MySQL server is not running on the default port (3306) on localhost (or you didn't name the database iou), make the appropriate changes to the jdbc.url config parameter in resources/config.properties
• Create the database table and triggers via the SQL script src/main/resources/schema.sql
• Create two MySQL users that have read-write access to the iou database
• In config.properties set ann.username to the MySQL login of one of the users and set bob.username to the MySQL login of the other user
• In the same file, set ann.name and bob.name to the names that IOU will display for each of these users
• If $ is not used as the currency symbol in your locale, also set currency.symbol to whatever you wish to use instead

Database Initialization Example

Assuming the following:

• We are using the default database name "iou"
• We are using the default names for both MySQL users ("ann" and "bob")
• Both database users are using the password "secret"
• The current directory is set to the root of this project

The database initialization steps described in the previous section can be performed by logging into MySQL as the root user and executing the following commands

mysql> create database iou;
mysql> use iou;
mysql> source src/main/resources/schema.sql
mysql> create user ann@localhost identified by 'secret';
mysql> create user bob@localhost identified by 'secret';
mysql> grant all on iou.* to ann@localhost;
mysql> grant all on iou.* to bob@localhost;

Run IOU

Run the application either by downloading and launching the executable JAR or build and run from source.

Download executable

Download iou.jar from the releases and launch it with

java -jar iou.jar

When the application starts, the selected user should use their MySQL password to login.

Build and run from source

To build and run the application from source with Maven, execute the command below from the project's root directory:

mvn compile exec:java -Dexec.mainClass=iou.gui.AppLauncher

When the application starts, the selected user should use their MySQL password to login.