java 科学计算器

以下是一个Java科学计算器的示例代码，它包括了加减乘除、三角函数、指数运算、阶乘运算、求倒数、退格和清零等功能：

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

public class ScientificCalculator extends JFrame implements ActionListener {
    private JTextField displayField;
    private double num1, num2, result;
    private int operator;
    private boolean isDecimal;

    public ScientificCalculator() {
        setTitle("Scientific Calculator");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 300);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(5, 4));

        displayField = new JTextField();
        displayField.setEditable(false);
        panel.add(displayField);

        JButton button0 = new JButton("0");
        button0.addActionListener(this);
        panel.add(button0);

        JButton button1 = new JButton("1");
        button1.addActionListener(this);
        panel.add(button1);

        JButton button2 = new JButton("2");
        button2.addActionListener(this);
        panel.add(button2);

        JButton button3 = new JButton("3");
        button3.addActionListener(this);
        panel.add(button3);

        JButton button4 = new JButton("4");
        button4.addActionListener(this);
        panel.add(button4);

        JButton button5 = new JButton("5");
        button5.addActionListener(this);
        panel.add(button5);

        JButton button6 = new JButton("6");
        button6.addActionListener(this);
        panel.add(button6);

        JButton button7 = new JButton("7");
        button7.addActionListener(this);
        panel.add(button7);

        JButton button8 = new JButton("8");
        button8.addActionListener(this);
        panel.add(button8);

        JButton button9 = new JButton("9");
        button9.addActionListener(this);
        panel.add(button9);

        JButton buttonDot = new JButton(".");
        buttonDot.addActionListener(this);
        panel.add(buttonDot);

        JButton buttonPlus = new JButton("+");
        buttonPlus.addActionListener(this);
        panel.add(buttonPlus);

        JButton buttonMinus = new JButton("-");
        buttonMinus.addActionListener(this);
        panel.add(buttonMinus);

        JButton buttonMultiply = new JButton("*");
        buttonMultiply.addActionListener(this);
        panel.add(buttonMultiply);

        JButton buttonDivide = new JButton("/");
        buttonDivide.addActionListener(this);
        panel.add(buttonDivide);

        JButton buttonSin = new JButton("sin");
        buttonSin.addActionListener(this);
        panel.add(buttonSin);

        JButton buttonCos = new JButton("cos");
        buttonCos.addActionListener(this);
        panel.add(buttonCos);

        JButton buttonTan = new JButton("tan");
        buttonTan.addActionListener(this);
        panel.add(buttonTan);

        JButton buttonExp = new JButton("exp");
        buttonExp.addActionListener(this);
        panel.add(buttonExp);

        JButton buttonFactorial = new JButton("!");
        buttonFactorial.addActionListener(this);
        panel.add(buttonFactorial);

        JButton buttonReciprocal = new JButton("1/x");
        buttonReciprocal.addActionListener(this);
        panel.add(buttonReciprocal);

        JButton buttonBackspace = new JButton("←");
        buttonBackspace.addActionListener(this);
        panel.add(buttonBackspace);

        JButton buttonClear = new JButton("C");
        buttonClear.addActionListener(this);
        panel.add(buttonClear);

        JButton buttonEqual = new JButton("=");
        buttonEqual.addActionListener(this);
        panel.add(buttonEqual);

        add(panel);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        if (command.equals("0")) {
            displayField.setText(displayField.getText() + "0");
        } else if (command.equals("1")) {
            displayField.setText(displayField.getText() + "1");
        } else if (command.equals("2")) {
            displayField.setText(displayField.getText() + "2");
        } else if (command.equals("3")) {
            displayField.setText(displayField.getText() + "3");
        } else if (command.equals("4")) {
            displayField.setText(displayField.getText() + "4");
        } else if (command.equals("5")) {
            displayField.setText(displayField.getText() + "5");
        } else if (command.equals("6")) {
            displayField.setText(displayField.getText() + "6");
        } else if (command.equals("7")) {
            displayField.setText(displayField.getText() + "7");
        } else if (command.equals("8")) {
            displayField.setText(displayField.getText() + "8");
        } else if (command.equals("9")) {
            displayField.setText(displayField.getText() + "9");
        } else if (command.equals(".")) {
            if (!isDecimal) {
                displayField.setText(displayField.getText() + ".");
                isDecimal = true;
            }
        } else if (command.equals("+")) {
            num1 = Double.parseDouble(displayField.getText());
            operator = 1;
            displayField.setText("");
            isDecimal = false;
        } else if (command.equals("-")) {
            num1 = Double.parseDouble(displayField.getText());
            operator = 2;
            displayField.setText("");
            isDecimal = false;
        } else if (command.equals("*")) {
            num1 = Double.parseDouble(displayField.getText());
            operator = 3;
            displayField.setText("");
            isDecimal = false;
        } else if (command.equals("/")) {
            num1 = Double.parseDouble(displayField.getText());
            operator = 4;
            displayField.setText("");
            isDecimal = false;
        } else if (command.equals("sin")) {
            num1 = Double.parseDouble(displayField.getText());
            result = Math.sin(num1);
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("cos")) {
            num1 = Double.parseDouble(displayField.getText());
            result = Math.cos(num1);
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("tan")) {
            num1 = Double.parseDouble(displayField.getText());
            result = Math.tan(num1);
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("exp")) {
            num1 = Double.parseDouble(displayField.getText());
            result = Math.exp(num1);
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("!")) {
            num1 = Double.parseDouble(displayField.getText());
            result = factorial(num1);
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("1/x")) {
            num1 = Double.parseDouble(displayField.getText());
            result = 1 / num1;
            displayField.setText(Double.toString(result));
            isDecimal = false;
        } else if (command.equals("←")) {
            String text = displayField.getText();
            if (text.length() > 0) {
                if (text.charAt(text.length() - 1) == '.') {
                    isDecimal = false;
                }
                displayField.setText(text.substring(0, text.length() - 1));
            }
        } else if (command.equals("C")) {
            displayField.setText("");
            isDecimal = false;
        } else if (command.equals("=")) {
            num2 = Double.parseDouble(displayField.getText());
            switch (operator) {
                case 1:
                    result = num1 + num2;
                    break;
                case 2:
                    result = num1 - num2;
                    break;
                case 3:
                    result = num1 * num2;
                    break;
                case 4:
                    result = num1 / num2;
                    break;
            }
            displayField.setText(Double.toString(result));
            isDecimal = false;
        }
    }

    private double factorial(double n) {
        if (n == 0) {
            return 1;
        } else {
            return n * factorial(n - 1);
        }
    }

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