MyJavaCalculator/SwingCalculator.java at main · aryansh77/MyJavaCalculator · GitHub

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import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class SwingCalculator extends JFrame implements ActionListener {
    private JTextField display;
    private StringBuilder currentInput = new StringBuilder();
    private double result = 0;
    private String lastOperator = "=";

    public SwingCalculator() {
        setTitle("Swing Calculator");
        setSize(350, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setResizable(false);

        // Display panel
        display = new JTextField();
        display.setFont(new Font("Arial", Font.BOLD, 32));
        display.setHorizontalAlignment(SwingConstants.RIGHT);
        display.setEditable(false);
        display.setBackground(Color.WHITE);
        display.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        add(display, BorderLayout.NORTH);

        // Button panel
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(5, 4, 5, 5));
        panel.setBackground(Color.DARK_GRAY);
        String[] buttons = {
            "C", "←", "%", "/",
            "7", "8", "9", "*",
            "4", "5", "6", "-",
            "1", "2", "3", "+",
            "±", "0", ".", "="
        };

        for (String text : buttons) {
            JButton btn = new JButton(text);
            btn.setFont(new Font("Arial", Font.BOLD, 24));
            btn.setForeground(Color.WHITE);
            btn.setBackground(Color.GRAY);
            btn.setFocusPainted(false);
            btn.addActionListener(this);
            panel.add(btn);
        }

        add(panel, BorderLayout.CENTER);
        getContentPane().setBackground(Color.BLACK);
        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand();

        if (cmd.matches("[0-9]") || cmd.equals(".")) {
            currentInput.append(cmd);
            display.setText(currentInput.toString());
        } else if (cmd.equals("C")) {
            currentInput.setLength(0);
            display.setText("");
            result = 0;
            lastOperator = "=";
        } else if (cmd.equals("←")) {
            if (currentInput.length() > 0) {
                currentInput.deleteCharAt(currentInput.length() - 1);
                display.setText(currentInput.toString());
            }
        } else if (cmd.equals("±")) {
            if (currentInput.length() > 0) {
                if (currentInput.charAt(0) == '-') {
                    currentInput.deleteCharAt(0);
                } else {
                    currentInput.insert(0, '-');
                }
                display.setText(currentInput.toString());
            }
        } else if (cmd.equals("=")) {
            calculate(Double.parseDouble(currentInput.toString()));
            display.setText(String.valueOf(result));
            currentInput.setLength(0);
            lastOperator = "=";
        } else { // operators +, -, *, /, %
            if (currentInput.length() > 0) {
                calculate(Double.parseDouble(currentInput.toString()));
                currentInput.setLength(0);
            }
            lastOperator = cmd;
        }
    }

    private void calculate(double number) {
        switch (lastOperator) {
            case "+": result += number; break;
            case "-": result -= number; break;
            case "*": result *= number; break;
            case "/": result /= number; break;
            case "%": result %= number; break;
            case "=": result = number; break;
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(SwingCalculator::new);
    }
}