Phoenix Calculator

A desktop calculator built with JavaFX 25 and Java 25: a frameless, draggable window styled with CSS, a pure calculator engine built on records, sealed types and pattern matching, and native installers for Windows, macOS and Linux.

Download

Get the latest package from Releases. Every package bundles its own Java runtime, so you don't need Java installed.

OS	Package	How to run
Windows (x64)	.msi installer or portable .zip	Run the installer, or unzip and start PhoenixCalculator.exe
macOS (Apple Silicon)	.dmg	Open the image and drag the app to Applications
Linux (x64)	.deb or portable .tar.gz	sudo apt install ./PhoenixCalculator-*.deb, or extract and run PhoenixCalculator/bin/PhoenixCalculator

The packages are not code-signed. On first launch:

• Windows SmartScreen shows a warning. Choose More info → Run anyway.
• macOS Gatekeeper may block the app. Right-click it and choose Open, or allow it in System Settings → Privacy & Security.

Features

• Arithmetic: addition, subtraction, multiplication, division, percent and sign change, with a decimal comma.
• Expression line: shows the calculation above the result, e.g. 1000 + 24 =.
• Repeat: pressing = again repeats the last operation (1 + 2 = = gives 5).
• Precision: results keep 16 significant digits. Very large and very small numbers switch to scientific notation.
• Errors: division by zero shows undefined until you enter a new number or clear.
• Keyboard: full keyboard support, with the pressed button animating as if clicked.
• Window: frameless and transparent with its own minimize and close buttons; drag it anywhere to move it.
• Startup: shows a splash screen through a JavaFX Preloader.

Keyboard shortcuts

Key	Action
0–9, numpad digits	Digit
,, numpad decimal point	Decimal comma
+ (Shift+=, numpad +)	Add
-, numpad -	Subtract
* (Shift+8, numpad *)	Multiply
/, numpad /	Divide
% (Shift+5)	Percent
Enter, =	Result
Backspace	Delete the last character of the number being typed
Esc, Delete	Clear

Shift combinations assume a US keyboard layout. Sign change (+/-) is button-only.

Build from source

You need JDK 25 or newer (JAVA_HOME must point to it). The Maven Wrapper downloads Maven itself.

./mvnw javafx:run        # run the app
./mvnw verify            # build and run the tests

To build native packages for your OS into target/release:

packaging/package.sh 1.0.0

On Windows, run the script from Git Bash. Building an .msi also needs WiX 5 with its UI and Util extensions:

dotnet tool install --global wix --version 5.0.2
wix extension add -g WixToolset.Util.wixext/5.0.2 WixToolset.UI.wixext/5.0.2

Releasing

Push a version tag, for example git tag v1.0.0 && git push origin v1.0.0. The Release workflow then tests and packages the app on Windows, macOS and Linux and publishes a GitHub Release with all packages attached.

Architecture

eu.mapidev.calculator.phoenix
├── ApplicationLauncher, ApplicationLoader   JavaFX Application + Preloader (splash screen)
├── MainController                           FXML controller: window controls, buttons, keyboard
├── CalculatorViewModel                      observable state for the view
├── CalculatorKeyBindings                    key event -> calculator input
└── engine                                   pure calculator logic, no JavaFX dependency
    ├── CalculatorInput    sealed interface: CalculatorDigit | ArithmeticOperation | Command
    ├── CalculatorState    immutable record: display, memory line, operands, last input
    ├── CalculatorEngine   apply(state, input) -> new state
    └── DisplayFormat      BigDecimal <-> display text

• Engine. The engine is a pure function, CalculatorEngine.apply(CalculatorState, CalculatorInput).

  • An exhaustive pattern-matching switch over the sealed CalculatorInput handles every input.
  • Each step returns a new immutable CalculatorState, which makes the logic easy to test.

• View model. CalculatorViewModel keeps the state in a JavaFX property and exposes the result and memory line with ObservableValue.map. MainController binds the labels to them.

  • The view model uses only javafx.base, so its tests need no UI toolkit.

• Buttons. Each button in main-view.fxml carries its input token in userData, for example userData="+/-". Button labels are free text and don't drive the logic.

• Tests. The behaviour is specified by CalculatorScenarioTest, a table of key sequences with the expected result and memory line:

  # keys                  | result    | memory
  2 0 0 + 1 0 = 5 x 2 =   | 10        | 5 x 2 =
  1 / 0 =                 | undefined | ''
  

Tech stack

Area	Tools
Language	Java 25 (records, sealed interfaces, pattern-matching switch)
UI	JavaFX 25 (FXML, CSS, properties and bindings, Preloader)
Build and tests	Maven Wrapper, JUnit 6 with parameterized tests
Packaging and CI	jlink and jpackage, GitHub Actions (CI plus release builds on three OSes)

Author

mperor