AdvancedCalculator.java

// Essential imports for GUI components, event handling, and utilities
// Includes Swing/AWT for interface elements and event listeners
// Collections from java.util for data structures (ArrayList, HashSet)

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;

// Main calculator class extending JFrame for GUI window and implementing ActionListener for button events
public class AdvancedCalculator extends JFrame implements ActionListener {
    private JTextField display;          // Text field to show input and results
    private StringBuilder input;         // Stores the current input expression
    private ArrayList<String> history;   // Keeps track of past calculations
    private double memory;               // Stores value for memory recall (MR) function
    private static final Set<String> UNARY_FUNCTIONS = new HashSet<>();  // Set of supported math functions

// Static initializer block to populate the set of unary mathematical functions
// Adds trigonometric functions (sin, cos, tan, cot, sec, csc) and other operations (log, sqrt)
// These functions will be available as single-operand operations in the calculator
static {
    UNARY_FUNCTIONS.add("sin");
    UNARY_FUNCTIONS.add("cos");
    UNARY_FUNCTIONS.add("tan");
    UNARY_FUNCTIONS.add("log");
    UNARY_FUNCTIONS.add("sqrt");
    UNARY_FUNCTIONS.add("cot");
    UNARY_FUNCTIONS.add("sec");
    UNARY_FUNCTIONS.add("csc");
}


public AdvancedCalculator() {
    setTitle("Advanced Calculator");                           // Sets the window title
    setSize(600, 700);                             // Sets window dimensions
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);            // Defines window close behavior
    setLayout(new BorderLayout());                             // Sets the main layout manager
    getContentPane().setBackground(new Color(38, 38, 38));       // Sets dark background color

    // Get the screen dimensions
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();   // Gets screen resolution
    // Get the frame dimensions
    Dimension frameSize = getSize();                                      // Gets calculator window size
    // Center the frame
    setLocation(                                                         // Centers the window on screen
            (screenSize.width - frameSize.width) / 2,                    // Calculates x position
            (screenSize.height - frameSize.height) / 2                   // Calculates y position
    );

    input = new StringBuilder();                                  // Initializes input buffer
    history = new ArrayList<>();                                  // Initializes calculation history
    memory = 0.0;                                                 // Initializes memory function

    display = new JTextField();                                   // Creates display field
    display.setFont(new Font("SansSerif", Font.BOLD, 60));        // Sets display font
    display.setHorizontalAlignment(JTextField.RIGHT);                // Right-aligns display text
    display.setForeground(Color.WHITE);                              // Sets text color to white
    display.setBackground(new Color(51, 51, 51));            // Sets display background
    display.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); // Adds padding
    display.setEditable(false);                                    // Makes display read-only
    add(display, BorderLayout.NORTH);                              // Adds display to top

    display.setCaretColor(new Color(240, 240, 240));              // Sets cursor color
    display.setSelectionColor(new Color(0, 240, 240, 240));    // Sets text selection color

    JPanel panel = new JPanel();                                  // Creates button panel
    panel.setLayout(new GridLayout(8, 4, 10, 10));               // Sets grid layout with gaps
    panel.setBackground(new Color(38, 38, 38));                               // Sets panel background
    panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); // Adds panel padding

    // Array of button labels arranged in a 8x4 grid layout:
    String[] buttons = {
            "sin", "cos", "tan", "cot",
            "sec", "csc", "sqrt", "log",
            "^", "M+", "MR", "H",
            "(", ")", "DEL", "AC",
            "7", "8", "9", "/",
            "4", "5", "6", "x",
            "1", "2", "3", "-",
            "0", ".", "+", "="
    };

    for (String text : buttons) {                                        // Iterate through button labels
        JButton button = new RoundedButton(text);                        // Create custom rounded button
        button.setFont(new Font("JetBrains Mono", Font.BOLD, 30));     // Set button font style and size
        button.addActionListener(this);                                // Add click event handler

        if (Arrays.asList(buttons).indexOf(text) < 8) {
            button.setForeground(new Color(0, 162, 255)); // Light blue for first two rows
        } else if (text.equals("DEL") || text.equals("AC")) {
            button.setForeground(new Color(255, 69, 58)); // Red for DEL and AC
        } else if (text.equals("M+") || text.equals("MR") || text.equals("H")) {
            button.setForeground(new Color(243, 209, 24)); // Red for DEL and AC
        } else {
            button.setForeground(new Color(240, 240, 240)); // White for all other buttons
        }
        if (text.equals("=")) {
            button.setBackground(new Color(37, 175, 236));       // Sets light blue background for equals button
        } else {
            button.setBackground(new Color(77, 77, 77));         // Sets dark gray background for other buttons
        }
        button.setFocusPainted(false);                             // Removes focus border/highlight
        button.putClientProperty("JButton.buttonType", "roundRect"); // Sets button shape to rounded rectangle
        panel.add(button);                                         // Adds the configured button to panel
    }

    add(panel, BorderLayout.CENTER);           // Adds the button panel to center of calculator window
    setVisible(true);                          // Makes the calculator window visible on screen
}

@Override
public void actionPerformed(ActionEvent e) {
    String command = e.getActionCommand();                    // Get the text from the button that was clicked

    if (command.equals("AC")) {                              // All Clear button pressed
        input.setLength(0);                                  // Clear the input buffer
        display.setText("");                                 // Clear the display
    } else if (command.equals("DEL")) {                     // Delete button pressed
        if (!input.isEmpty()) {                             // If there's input to delete
            input.delete(input.length() - 1, input.length());// Remove last character
            display.setText(input.toString());               // Update display
        }
    } else if (command.equals("=")) {                       // Equals button pressed
        try {
            double result = evaluateExpression(input.toString());    // Calculate result
            history.add(input.toString() + " = " + result);          // Add to history
            display.setText(String.format("%.6f", result));          // Show result with 6 decimals
            input.setLength(0);                                      // Clear input buffer
        } catch (Exception ex) {
            display.setText("Error");                                // Show error on invalid expression
            input.setLength(0);                                      // Clear input buffer
        }
    } else if (command.equals("M+")) {                      // Memory store button pressed
        try {
            memory = Double.parseDouble(display.getText());  // Store current display value in memory
        } catch (NumberFormatException ex) {
            display.setText("Error");                        // Show error if value invalid
        }
    } else if (command.equals("MR")) {                      // Memory recall button pressed
        display.setText(String.valueOf(memory));            // Show stored memory value
    } else if (command.equals("H")) {                       // History button pressed
        JOptionPane.showMessageDialog(this,          // Show history dialog
            String.join("\n", history),                 // Join history entries with newlines
            "Calculation History",                      // Dialog title
            JOptionPane.INFORMATION_MESSAGE);           // Dialog type
    } else {
        input.append(command);                              // Add button text to input
        display.setText(input.toString());                  // Update display with new input
    }
}

private double evaluateExpression(String expression) throws Exception {
        return evaluatePostfix(infixToPostfix(expression));    // Convert infix to postfix and evaluate
    }

private String infixToPostfix(String expression) {
    StringBuilder output = new StringBuilder();                    // Store postfix expression
    Stack<String> operators = new Stack<>();                       // Stack for operators
    // Split expression keeping operators and parentheses separate
    String[] tokens = expression.split("(?<=[-+x/^()])|(?=[-+x/^()])");

    for (String token : tokens) {
        token = token.trim();                                      // Remove whitespace
        if (token.matches("\\d+(\\.\\d+)?")) {                    // If token is a number
            output.append(token).append(" ");                      // Add to output
        } else if (UNARY_FUNCTIONS.contains(token) || token.equals("(")) {  // If function or open parenthesis
            operators.push(token);                                 // Push to operator stack
        } else if (token.equals(")")) {                           // If closing parenthesis
            while (!operators.isEmpty() && !operators.peek().equals("(")) {  // Until matching open parenthesis
                output.append(operators.pop()).append(" ");        // Pop operators to output
            }
            operators.pop();                                       // Remove open parenthesis
        } else {                                                  // If operator
            // Pop operators with higher/equal precedence
            while (!operators.isEmpty() && precedence(token.charAt(0)) <= precedence(operators.peek().charAt(0))) {
                output.append(operators.pop()).append(" ");
            }
            operators.push(token);                                 // Push current operator
        }
    }

    while (!operators.isEmpty()) {                                // Pop remaining operators
        output.append(operators.pop()).append(" ");
    }

    return output.toString();
}

private double evaluatePostfix(String postfix) throws Exception {
    Stack<Double> stack = new Stack<>();                          // Stack for operands
    for (String token : postfix.split(" ")) {                    // Process each token
        if (token.isEmpty()) continue;                           // Skip empty tokens
        try {
            stack.push(Double.parseDouble(token));               // Try to parse as number
        } catch (NumberFormatException e) {                      // If token is operator/function
            double a = stack.pop();                              // Pop operand
            switch (token) {
                case "sin": stack.push(Math.sin(Math.toRadians(a))); break;  // Sine function
                case "cos": stack.push(Math.cos(Math.toRadians(a))); break;  // Cosine function
                case "tan": stack.push(Math.tan(Math.toRadians(a))); break;  // Tangent function
                case "log": stack.push(Math.log10(a)); break;                // Log base 10
                case "sqrt": stack.push(Math.sqrt(a)); break;               // Square root
                case "cot": stack.push(1 / Math.tan(Math.toRadians(a))); break;  // Cotangent
                case "sec": stack.push(1 / Math.cos(Math.toRadians(a))); break;  // Secant
                case "csc": stack.push(1 / Math.sin(Math.toRadians(a))); break;  // Cosecant
                case "+": stack.push(stack.pop() + a); break;               // Addition
                case "-": stack.push(stack.pop() - a); break;               // Subtraction
                case "x": stack.push(stack.pop() * a); break;               // Multiplication
                case "/": stack.push(stack.pop() / a); break;               // Division
                case "^": stack.push(Math.pow(stack.pop(), a)); break;      // Exponentiation
                default: throw new Exception("Invalid Operator");           // Unknown operator
            }
        }
    }
    return stack.pop();                                          // Return final result
}

private int precedence(char operator) {
    return switch (operator) {
        case '+', '-' -> 1;      // Lowest precedence for addition and subtraction
        case 'x', '/' -> 2;      // Medium precedence for multiplication and division
        case '^' -> 3;           // Highest precedence for exponentiation
        default -> 0;            // Default precedence for other characters
    };
}


class RoundedButton extends JButton {
    public RoundedButton(String text) {
        super(text);                        // Call parent constructor with button text
        setContentAreaFilled(false);        // Disable default button fill
        setFocusPainted(false);            // Remove focus border/highlight
        setBorderPainted(false);            // Remove button border
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D) g.create();    // Create graphics context for custom painting
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,    // Enable antialiasing
                RenderingHints.VALUE_ANTIALIAS_ON);             // for smoother edges

        g2.setColor(getBackground());               // Set default background color

        if (getModel().isPressed()) {              // If button is being pressed
            g2.setColor(getBackground().darker());  // Darken the background
        } else if (getModel().isRollover()) {      // If mouse is over button
            g2.setColor(new Color(100, 100, 100)); // Use hover color
        }

        // Draw rounded rectangle for button shape (40px corner radius)
        g2.fillRoundRect(0, 0, getWidth(), getHeight(), 40, 40);
        g2.dispose();                              // Clean up graphics context

        super.paintComponent(g);                   // Paint button text/icon
    }
}
        
    public static void main(String[] args) {
        new AdvancedCalculator();    // Create and display calculator window
    }
}