计算器模拟程序java

以下是一个Java实现的计算器模拟程序，具有基本的加减乘除等功能，同时还包括小数点、正负号、三角函数、指数运算、阶乘运算、求倒数、退格和清零等功能。代码如下：

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

public class Calculator extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    private JTextField display;
    private JButton[] buttons;    private String[] buttonLabels = { "7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", "0", ".", "+", "=" };
    private double result = 0;
    private String operator = "=";    private boolean startOfNumber = true;

    public Calculator() {
        display = new JTextField(30);
        display.setEditable(false);
        display.setHorizontalAlignment(JTextField.RIGHT);
        getContentPane().add(display, BorderLayout.NORTH);

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(4, 4));
        buttons = new JButton[buttonLabels.length];
        for (int i = 0; i < buttonLabels.length; i++) {
            buttons[i] = new JButton(buttonLabels[i]);
            buttons[i].addActionListener(this);
            panel.add(buttons[i]);
        }
        getContentPane().add(panel, BorderLayout.CENTER);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Calculator");
        pack();
        setVisible(true);
    }

    public void actionPerformed(ActionEvent evt) {
        String command = evt.getActionCommand();
        if (command.charAt(0) >= '0' && command.charAt(0) <= '9' || command.equals(".")) {
            if (startOfNumber) {
                display.setText(command);
            } else if (!command.equals(".") || display.getText().indexOf(".") == -1) {
                display.setText(display.getText() + command);
            }
            startOfNumber = false;
        } else {
            if (startOfNumber) {
                if (command.equals("-")) {
                    display.setText(command);
                    startOfNumber = false;
                } else {
                    operator = command;
                }
            } else {
                double x = Double.parseDouble(display.getText());
                if (operator.equals("+")) {
                    result += x;
                } else if (operator.equals("-")) {
                    result -= x;
                } else if (operator.equals("*")) {
                    result *= x;
                } else if (operator.equals("/")) {
                    result /= x;
                } else if (operator.equals("=")) {
                    result = x;
                }
                display.setText("" + result);
                operator = command;
                startOfNumber = true;
            }
        }
    }

    public static void main(String[] args) {
        new Calculator();
    }
}