Java Swing Calculator

A lightweight desktop calculator built with Java Swing. The project demonstrates graphical user-interface construction, event-driven programming, input parsing, and basic error handling in a compact Java application.

Features

• Addition, subtraction, multiplication, and division
• Button-based input for digits and operators
• Clear (C) and calculate (=) actions
• Support for multi-digit values
• Decimal results through double arithmetic
• Validation for malformed expressions
• Explicit handling of division by zero
• Swing event handling through a shared ActionListener

Technologies

• Java
• Java Swing
• AWT event handling

No third-party dependencies are required.

Requirements

• JDK 8 or newer
• A desktop environment capable of displaying Swing applications

Run locally

Clone the repository:

git clone https://github.com/andreiboscu/java-swing-calculator.git
cd java-swing-calculator

Compile the application:

javac -d out Calculator.java

Run it:

java -cp out lab7.Calculator

You can also import Calculator.java into IntelliJ IDEA, Eclipse, or another Java IDE and run the main method.

Usage

Enter an expression using the calculator buttons, then press =.

Example:

123 + 7

The calculator expects one operation at a time in the form:

number operator number

Press C to clear the display. Invalid input produces an error message, while division by zero is reported separately.

Project structure

.
├── Calculator.java
├── LICENSE
├── README.md
└── .gitignore

Concepts demonstrated

Java · Swing · GUI Development · ActionListener · Event-Driven Programming · Input Validation · Exception Handling

Possible future improvements

• Add decimal-point and backspace buttons
• Support chained calculations
• Improve keyboard input
• Use layout managers for responsive resizing
• Separate calculation logic from the graphical interface
• Add automated unit tests
• Package the application as an executable JAR

License

This project is available under the MIT License.