Calculator App

This project is an Android-based calculator app that performs basic arithmetic and power calculations. The app features a clean user interface and supports expressions with parentheses, decimal values, and exponents. Below is a detailed description of the app and instructions for building and running it.

Features

1. Basic Arithmetic Operations:

   • Addition (+)
   • Subtraction (-)
   • Multiplication (*)
   • Division (/)

2. Exponentiation:

   • The ^ operator is used to calculate powers. It is converted internally to Math.pow() for accurate results.

3. Parentheses Handling:

   • Users can add parentheses ( and ) for complex expressions.
   • Bracket balancing is enforced to avoid invalid inputs.

4. Backspace Functionality:

   • Users can remove the last entered character using the backspace button.

5. Clear Button:

   • Resets the entire input and result display.

6. Scientific Notation Support:

   • Results are displayed in scientific notation (E format) if necessary.

7. Error Handling:

   • Detects and handles invalid expressions (e.g., unmatched parentheses, invalid syntax).

8. Formatted Results:

   • Results are formatted to display up to 8 significant digits for precision and clarity.

User Interface

• A screenshot of the calculator app's interface is included in the repository.
• The UI consists of the following components:
  • Workings TextView: Displays the user-entered expression.
  • Results TextView: Displays the calculated result.
  • Buttons: Number keys (0-9), operators, parentheses, clear, backspace, and equals.

Video

Screenrecorder-2025-01-05-01-17-48-565.mp4

Code Overview

The app is built using Java for Android. Below is an overview of the key files:

MainActivity.java

• Handles the logic for the calculator's functionality.
• Includes methods to handle button clicks and update the display.
• Uses the ScriptEngine from Java's javax.script package to evaluate mathematical expressions.

Key Methods

1. setWorkings(String givenValue):

   • Updates the expression displayed in the workings TextView.

2. equalOnClick(View view):

   • Evaluates the current expression and displays the result.
   • Converts the ^ operator to Math.pow() for power calculations.

3. checkForPowerOf():

   • Processes the input expression to identify and replace the ^ operator with Math.pow() syntax.

4. changeFormula(Integer index):

   • Handles parentheses and numeric extraction for the ^ operator.
   • Ensures proper syntax for power calculations.

5. findClosingParenthesis(int openIndex) and findOpeningParenthesis(int closeIndex):

   • Identify matching parentheses for complex expressions.

6. backSpaceOnClick(View view):

   • Removes the last character from the input expression.

activity_main.xml

• Defines the layout of the calculator app.
• Includes buttons for digits, operators, and other controls.

Build and Run Instructions

1. Prerequisites:

   • Android Studio installed on your computer.
   • Java Development Kit (JDK) configured.

2. Clone the Repository:

   git clone <repository_url>
   cd <repository_folder>

3. Open in Android Studio:

   • Open Android Studio.
   • Select "Open an Existing Project" and navigate to the cloned repository.

4. Build the Project:

   • Click on "Build" > "Make Project" or press Ctrl+F9.

5. Run the App:

   • Connect an Android device or start an emulator.
   • Click the "Run" button or press Shift+F10.

Usage

• Enter a mathematical expression using the buttons.
• Use = to calculate the result.
• Use C to clear all input, or the backspace button to remove the last character.

Example Expressions

• 7 + 3 * (10 / (12 / (3 + 1) - 1))
• 2^3
• 5 + (6 * 7) - 8 / 4

Screenshots

         

Limitations

• Currently, the app supports only basic arithmetic and power operations.
• Advanced mathematical functions (e.g., trigonometry, logarithms) are not included.

Future Enhancements

1. Add support for additional operators and functions (e.g., sin, cos, log).
2. Provide an option to switch between E and 10^ notations.
3. Improve error messages for invalid input.
4. Enhance UI for better usability on different screen sizes.

License

This project is licensed under the MIT License - see the (https://en.wikipedia.org/wiki/MIT_License#:~:text=The%20MIT%20License%20is%20a,therefore%20has%20high%20license%20compatibility.) for details.

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Feel free to suggest improvements or report issues by creating a new issue in the repository!