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


public class SimpleCalculator extends JFrame {

    private JTextField display;
    private JPanel panel;
    private double operand1 = 0;
    private double operand2 = 0;
    private char operator;
    private boolean userIsTypingSecondNumber = false;

    public SimpleCalculator() {
        setTitle("Simple Calculator");
        setSize(400, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        // Display text field
        display = new JTextField();
        display.setEditable(false);
        display.setHorizontalAlignment(SwingConstants.RIGHT);
        add(display, BorderLayout.NORTH);

        // Panel for buttons
        panel = new JPanel();
        panel.setLayout(new GridLayout(5, 4, 10, 10));

        // Add numbers and operations to panel
        String[] buttons = {
                "7", "8", "9", "/",
                "4", "5", "6", "*",
                "1", "2", "3", "-",
                "0", ".", "=", "+",
                "C"
        };

        for (String text : buttons) {
            JButton button = new JButton(text);
            button.setFont(new Font("Verdana", Font.PLAIN, 24));
            button.setFocusable(false);
            panel.add(button);
            button.addActionListener(new ButtonClickListener());
        }

        add(panel, BorderLayout.CENTER);
    }