JavaFX Calculator for beginners

A modern calculator with a polished interface, written in JavaFX. It supports keyboard and mouse input, features a dark theme, and follows a professional architecture.

Modern JavaFX calculator with a dark theme

---

Features

Functionality

• Basic operations: addition, subtraction, multiplication, division
• Additional functions: percentage (%), sign toggle (±), clear (C)
• Keyboard control: full support for keyboard and Numpad input
• Error handling: division by zero, invalid input
• Correct rounding: automatic removal of trailing zeros

Design

• Dark theme: modern, minimalist design
• Animations: hover and press effects
• Responsive layout: fixed size of 400×600 px
• Professional color scheme: orange operators, gray digits

Controls

• Mouse: click all buttons
• Keyboard: digits, Enter, Escape, Backspace
• Numpad: full numeric keypad support
• Keyboard shortcuts:
  • Enter or = — calculate
  • Escape or Delete — clear
  • Backspace — delete a character
  • Shift + = — plus sign

---

Project Structure

calculator/
├── src/main/java/ru/levitsky/calculator/
│   ├── Calculator.java              # Main application class
│   ├── constants/
│   │   ├── CalculatorConstants.java # Mathematical constants
│   │   ├── UIConstants.java         # Colors and UI constants
│   │   └── UIStyleConstants.java    # Styles and dimensions
│   └── util/
│       └── Utils.java               # Helper utilities
├── pom.xml                          # Maven configuration
└── README.md                        # Documentation

---

Quick Start

Prerequisites

• Java 25 (JDK 25 or higher)
• JavaFX SDK 21.0.6 (automatically downloaded via Maven)
• Maven 3.8+

Run from IDE (IntelliJ IDEA / Eclipse)

1. Clone the repository
2. Open the project in your IDE
3. Ensure JavaFX SDK is configured
4. Run Calculator.java

Run from Command Line

Build with Maven:

mvn clean compile
mvn javafx:run

---

Developer Setup

Maven Configuration (pom.xml)

<dependencies>
    <dependency>
        <groupId>org.openjfx</groupId>
        <artifactId>javafx-controls</artifactId>
        <version>21</version>
    </dependency>
    <dependency>
        <groupId>org.openjfx</groupId>
        <artifactId>javafx-fxml</artifactId>
        <version>21</version>
    </dependency>
</dependencies>

---

How to Use

Basic Calculations

1. Enter the first number (e.g., 123.45)
2. Press an operator (+, -, ×, ÷)
3. Enter the second number (e.g., 67.89)
4. Press = or Enter to get the result

Notes

• Decimal point: automatically added only once
• Clear: C resets all calculations
• Sign toggle: ± inverts the sign of the current number
• Percentage: % divides the number by 100

---

Testing

The calculator has been tested with the following scenarios:

• Basic arithmetic operations
• Division by zero (shows an error message)
• Decimal number handling
• Keyboard input
• Large number processing
• Correct rounding behavior

---

Architectural Decisions

Separation of Responsibilities

• Calculator.java: controller and view
• Constants: separate classes for UI and logic
• Utilities: reusable helper functions

Event Handling

// Two-level event handling system
addEventFilter(KeyEvent.KEY_TYPED, this::handleKeyTyped);       // Typed characters
addEventFilter(KeyEvent.KEY_PRESSED, this::handleSpecialKeys); // Special keys

State Management

private double num1, num2;          // Operands
private String operator;            // Current operation
private boolean startNewNumber;     // Start new number flag
private boolean calculationDone;    // Calculation completed flag

---

Roadmap

Version 2.0 (in progress)

• Calculation history
• Memory buttons (M+, M-, MR, MC)
• Ctrl+C / Ctrl+V copy & paste support

Version 3.0 (planned)

• Scientific mode (sin, cos, sqrt, powers)
• Unit converter
• Light / dark theme toggle
• Expression support

---

Contributing

Pull requests are welcome! For major changes, please open an Issue first to discuss your ideas.

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

---

License

This project is licensed under the MIT License. See the LICENSE file for details.

---

Author

Levitsky

• GitHub: Anatoliy Levitsky
• Project: JavaFX Calculator