Calcswing.java

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

public class Calcswing extends JFrame implements ActionListener {
    private final JTextField display;
    private String operator;
    private double firstOperand, secondOperand, result;
    private boolean startNewNumber = true;

    public Calcswing() {
        setTitle("Calcswing");
        setSize(360, 520);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout(10, 10));
        getContentPane().setBackground(new Color(20, 20, 20));
        setResizable(false);

        display = new JTextField("0") {
            protected void paintComponent(Graphics g) {
                Graphics2D g2 = (Graphics2D) g;
                g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                GradientPaint gp = new GradientPaint(0, 0, new Color(45, 45, 45), 0, getHeight(), new Color(25, 25, 25));
                g2.setPaint(gp);
                g2.fillRect(0, 0, getWidth(), getHeight());
                super.paintComponent(g);
            }
        };
        display.setFont(new Font("Poppins", Font.BOLD, 38));
        display.setHorizontalAlignment(SwingConstants.RIGHT);
        display.setEditable(false);
        display.setForeground(new Color(255, 255, 255));
        display.setCaretColor(Color.WHITE);
        display.setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));
        display.setOpaque(false);
        add(display, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel(new GridLayout(5, 4, 10, 10));
        buttonPanel.setBackground(new Color(20, 20, 20));
        add(buttonPanel, BorderLayout.CENTER);

        String[] buttons = {
            "C", "←", "÷", "×",
            "7", "8", "9", "-",
            "4", "5", "6", "+",
            "1", "2", "3", "=",
            "0", ".", "+/-", "%"
        };

        for (String text : buttons) {
            JButton b = createButton(text);
            buttonPanel.add(b);
        }

        setLocationRelativeTo(null);
    }

    private JButton createButton(String text) {
        JButton b = new JButton(text);
        b.setFont(new Font("Poppins", Font.BOLD, 22));
        b.setFocusPainted(false);
        b.setForeground(Color.WHITE);
        b.setBackground(isOperator(text) ? new Color(255, 140, 0) : new Color(50, 50, 50));
        b.setBorder(BorderFactory.createLineBorder(new Color(30, 30, 30), 1, true));
        b.setCursor(new Cursor(Cursor.HAND_CURSOR));
        b.setOpaque(true);
        b.setBorderPainted(false);
        b.setActionCommand(text);
        b.addActionListener(this);

        b.addMouseListener(new MouseAdapter() {
            public void mouseEntered(MouseEvent e) {
                if (isOperator(text)) {
                    b.setBackground(new Color(255, 160, 0));
                    b.setBorder(BorderFactory.createLineBorder(new Color(255, 190, 90), 2, true));
                    // Swing doesn't support a shadow layer on JButton; skip custom shadow
                } else {
                    b.setBackground(new Color(70, 70, 70));
                    b.setBorder(BorderFactory.createLineBorder(new Color(200, 200, 200, 80), 2, true));
                }
            }
            public void mouseExited(MouseEvent e) {
                b.setBackground(isOperator(text) ? new Color(255, 140, 0) : new Color(50, 50, 50));
                b.setBorder(BorderFactory.createLineBorder(new Color(30, 30, 30), 1, true));
            }
        });
        return b;
    }

    private boolean isOperator(String t) {
        return t.equals("+") || t.equals("-") || t.equals("×") || t.equals("÷") || t.equals("=");
    }

    private void animateDisplay(String newText) {
        Timer timer = new Timer(10, null);
        final float[] alpha = {0f};
        timer.addActionListener(e -> {
            alpha[0] += 0.1f;
            if (alpha[0] >= 1f) {
                alpha[0] = 1f;
                ((Timer) e.getSource()).stop();
            }
            display.setForeground(new Color(255, 255, 255, (int) (alpha[0] * 255)));
            display.setText(newText);
        });
        timer.start();
    }

    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand();
        if (cmd.matches("[0-9]") || cmd.equals(".")) {
            if (startNewNumber) {
                animateDisplay(cmd.equals(".") ? "0." : cmd);
                startNewNumber = false;
            } else {
                if (!(cmd.equals(".") && display.getText().contains(".")))
                    animateDisplay(display.getText() + cmd);
            }
        } else if (isOperator(cmd) && !cmd.equals("=")) {
            operator = cmd;
            firstOperand = Double.parseDouble(display.getText());
            startNewNumber = true;
        } else if (cmd.equals("=")) {
            // if no operator was selected, do nothing
            if (operator == null || operator.isEmpty()) {
                // keep current display
                startNewNumber = true;
                return;
            }
            secondOperand = Double.parseDouble(display.getText());
            switch (operator) {
                case "+": result = firstOperand + secondOperand; break;
                case "-": result = firstOperand - secondOperand; break;
                case "×": result = firstOperand * secondOperand; break;
                case "÷": result = secondOperand != 0 ? firstOperand / secondOperand : Double.NaN; break;
                default: result = secondOperand; break;
            }
            animateDisplay(formatResult(result));
            startNewNumber = true;
        } else if (cmd.equals("C")) {
            animateDisplay("0");
            operator = null;
            firstOperand = secondOperand = result = 0;
            startNewNumber = true;
        } else if (cmd.equals("←")) {
            String text = display.getText();
            if (text.length() > 1)
                animateDisplay(text.substring(0, text.length() - 1));
            else
                animateDisplay("0");
        } else if (cmd.equals("+/-")) {
            double val = Double.parseDouble(display.getText());
            animateDisplay(formatResult(-val));
        } else if (cmd.equals("%")) {
            double val = Double.parseDouble(display.getText());
            animateDisplay(formatResult(val / 100));
        }
    }

    private String formatResult(double val) {
        if (val == (long) val) return String.format("%d", (long) val);
        return String.format("%.6f", val).replaceAll("0+$", "").replaceAll("\\.$", "");
    }

    public static void main(String[] args) {
        try { UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel"); } catch (Exception ignored) {}
        SwingUtilities.invokeLater(() -> new Calcswing().setVisible(true));
    }
}