基于swing的计算器sin

以下是一个基于 Swing 的计算器，包含 sin 函数的实现：

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", "/", "sin",
        "4", "5", "6", "*", "cos",
        "1", "2", "3", "-", "tan",
        "0", ".", "C", "+", "="
    };
    private JPanel buttonPanel;

    public Calculator() {
        super("Calculator");
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        display = new JTextField("0", 20);
        display.setEditable(false);
        display.setHorizontalAlignment(JTextField.RIGHT);
        getContentPane().add(display, BorderLayout.NORTH);

        buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(5, 5));
        buttons = new JButton[25];
        for (int i = 0; i < 25; i++) {
            buttons[i] = new JButton(buttonLabels[i]);
            buttons[i].addActionListener(this);
            buttonPanel.add(buttons[i]);
        }
        getContentPane().add(buttonPanel, BorderLayout.CENTER);

        pack();
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        if (command.equals("C")) {
            display.setText("0");
        } else if (command.equals("=")) {
            try {
                double result = eval(display.getText());
                display.setText(Double.toString(result));
            } catch (Exception ex) {
                display.setText("Error");
            }
        } else if (command.equals("sin")) {
            try {
                double result = Math.sin(Math.toRadians(Double.parseDouble(display.getText())));
                display.setText(Double.toString(result));
            } catch (Exception ex) {
                display.setText("Error");
            }
        } else if (command.equals("cos")) {
            try {
                double result = Math.cos(Math.toRadians(Double.parseDouble(display.getText())));
                display.setText(Double.toString(result));
            } catch (Exception ex) {
                display.setText("Error");
            }
        } else if (command.equals("tan")) {
            try {
                double result = Math.tan(Math.toRadians(Double.parseDouble(display.getText())));
                display.setText(Double.toString(result));
            } catch (Exception ex) {
                display.setText("Error");
            }
        } else {
            if (display.getText().equals("0")) {
                display.setText(command);
            } else {
                display.setText(display.getText() + command);
            }
        }
    }

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

    public static double eval(String str) {
        return new Object() {
            int pos = -1, ch;

            void nextChar() {
                ch = (++pos < str.length()) ? str.charAt(pos) : -1;
            }

            boolean eat(int charToEat) {
                while (ch == ' ') nextChar();
                if (ch == charToEat) {
                    nextChar();
                    return true;
                }
                return false;
            }

            double parse() {
                nextChar();
                double x = parseExpression();
                if (pos < str.length()) throw new RuntimeException("Unexpected: " + (char) ch);
                return x;
            }

            double parseExpression() {
                double x = parseTerm();
                for (;;) {
                    if (eat('+')) x += parseTerm(); // addition
                    else if (eat('-')) x -= parseTerm(); // subtraction
                    else return x;
                }
            }

            double parseTerm() {
                double x = parseFactor();
                for (;;) {
                    if (eat('*')) x *= parseFactor(); // multiplication
                    else if (eat('/')) x /= parseFactor(); // division
                    else return x;
                }
            }

            double parseFactor() {
                if (eat('+')) return parseFactor(); // unary plus
                if (eat('-')) return -parseFactor(); // unary minus

                double x;
                int startPos = this.pos;
                if (eat('(')) { // parentheses
                    x = parseExpression();
                    eat(')');
                } else if ((ch >= '0' && ch <= '9') || ch == '.') { // numbers
                    while ((ch >= '0' && ch <= '9') || ch == '.') nextChar();
                    x = Double.parseDouble(str.substring(startPos, this.pos));
                } else {
                    throw new RuntimeException("Unexpected: " + (char) ch);
                }

                if (eat('^')) x = Math.pow(x, parseFactor()); // exponentiation

                return x;
            }
        }.parse();
    }
}

这个计算器在每次点击 sin 按钮时，将文本框中的值解析为角度，然后计算 sine 函数的值，最后更新文本框的内容。cos 和 tan 函数的实现类似。