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

public class Code extends JFrame implements ActionListener {
    private JTextField display;
    private String operator;
    private double firstNumber, secondNumber, result;

    public Code() {
        // 设置窗口标题
        setTitle("jisuanqi");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        // 创建显示屏
        display = new JTextField();
        display.setFont(new Font("Arial", Font.BOLD, 24));
        display.setHorizontalAlignment(SwingConstants.RIGHT);
        display.setEditable(false);

        // 创建按钮面板
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4, 10, 10));

        String[] buttonLabels = {
            "7", "8", "9", "/",
            "4", "5", "6", "*",
            "1", "2", "3", "-",
            "0", ".", "=", "+"
        };

        for (String label : buttonLabels) {
            JButton button = new JButton(label);
            button.setFont(new Font("Arial", Font.BOLD, 20));
            button.addActionListener(this);
            buttonPanel.add(button);
        }

        // 添加组件到主窗口
        setLayout(new BorderLayout());
        add(display, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.CENTER);
    }

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

        if (command.charAt(0) >= '0' && command.charAt(0) <= '9' || command.equals(".")) {
            display.setText(display.getText() + command);
        } else if (command.equals("=")) {
            secondNumber = Double.parseDouble(display.getText());
            switch (operator) {
                case "+":
                    result = firstNumber + secondNumber;
                    break;
                case "-":
                    result = firstNumber - secondNumber;
                    break;
                case "*":
                    result = firstNumber * secondNumber;
                    break;
                case "/":
                    result = secondNumber != 0 ? firstNumber / secondNumber : 0;
                    break;
            }
            display.setText(String.valueOf(result));
        } else {
            firstNumber = Double.parseDouble(display.getText());
            operator = command;
            display.setText("");
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            Code calculator = new Code();
            calculator.setVisible(true);
        });
    }
}