📱 Calculator Demo – Android Calculator App Using Kotlin

This project is a simple yet functional calculator application developed using the Kotlin programming language in Android Studio. The application consists of two main parts: a user interface (AnasayfaFragment) and a backend logic handler (Operations).

🚀 Features

• Basic arithmetic operations supported: ➕ ➖ ✖️ ➗
• Real-time display of the current input
• Invalid input detection (e.g., prevents entering two operation symbols consecutively)
• Division-by-zero error handling
• Persistent state with SharedPreferences

🧩 Application Structure

🧱 AnasayfaFragment.kt

• Manages UI buttons and interactions.
• Updates the islem string with user input.
• On pressing the equals button (buttonesit), the input is passed to the Operations class for processing.
• Uses SharedPreferences to save the last operation string when the app is paused or stopped.

🧠 Operations.kt

• parcalama(islem: String): Splits the input string into numbers and operators.
• getNumbers() / getIsaretler(): Returns parsed numbers and operators.
• kontrolFonksiyonu(islem: String): Checks for invalid sequences like multiple consecutive operators.

📂 File Structure

hesapmakinesidemo/
├── AnasayfaFragment.kt       # UI and interaction logic
├── Operations.kt             # Parsing and calculation logic
├── fragment_anasayfa.xml     # UI layout (linked via ViewBinding)

🛠️ Setup

To run the project on your local machine:

1. Clone the repository:

   git clone https://github.com/emrullah-enis-ctnky/CalculatorAppAssignment.git
   

2. Open the project in Android Studio.
3. Ensure all SDKs and dependencies are installed.
4. Run on an emulator or a physical device.

⚙️ Technologies Used

• Kotlin
• Android SDK
• ViewBinding
• Fragment architecture
• SharedPreferences

🧠 What You'll Learn

By reviewing this project, you'll gain experience in:

• Fragment management in Kotlin
• Safe UI handling with ViewBinding
• Parsing user input for arithmetic evaluation
• Persisting state with SharedPreferences

🖼️ Screenshots

👤 Developer

Emrullah Enis Çetinkaya
🎓 Turkish-German University – Computer Engineering
🔗 GitHub Profile

📝 License

This project is licensed under the MIT License. For more information, see the LICENSE file.

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💡 Feel free to open a pull request if you'd like to contribute, report an issue, or suggest improvements!