基于java的科学计算器设计

以下是一个基于Java的科学计算器的设计示例代码，包括用户界面、表达式解析、计算功能和错误处理：

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

public class ScientificCalculator extends JFrame implements ActionListener {

    private JTextField inputField;
    private JLabel outputLabel;

    public ScientificCalculator() {
        setTitle("Scientific Calculator");
        setLayout(new FlowLayout());
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        inputField = new JTextField(20);
        add(inputField);

        JButton calculateButton = new JButton("Calculate");
        calculateButton.addActionListener(this);
        add(calculateButton);

        outputLabel = new JLabel("Result: ");
        add(outputLabel);

        pack();
        setLocationRelativeTo(null); // Center the window on the screen
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String input = inputField.getText();
        try {
            double result = evaluate(input);
            outputLabel.setText("Result: " + result);
        } catch (Exception ex) {
            outputLabel.setText("Error: " + ex.getMessage());
        }
    }

    private double evaluate(String input) throws Exception {
        // Parse the input expression
        String[] tokens = input.split(" ");
        Stack<Double> operands = new Stack<>();
        Stack<String> operators = new Stack<>();
        for (String token : tokens) {
            if (token.matches("\\d+\\.?\\d*")) {
                operands.push(Double.parseDouble(token));
            } else if (token.matches("[+\\-*/^]")) {
                while (!operators.isEmpty() && precedence(operators.peek()) >= precedence(token)) {
                    evaluate(operands, operators);
                }
                operators.push(token);
            } else if (token.equals("(")) {
                operators.push(token);
            } else if (token.equals(")")) {
                while (!operators.peek().equals("(")) {
                    evaluate(operands, operators);
                }
                operators.pop();
            } else {
                throw new Exception("Invalid token: " + token);
            }
        }
        while (!operators.isEmpty()) {
            evaluate(operands, operators);
        }
        if (operands.size() != 1) {
            throw new Exception("Invalid expression");
        }
        return operands.pop();
    }

    private void evaluate(Stack<Double> operands, Stack<String> operators) {
        double b = operands.pop();
        double a = operands.pop();
        String operator = operators.pop();
        switch (operator) {
            case "+":
                operands.push(a + b);
                break;
            case "-":
                operands.push(a - b);
                break;
            case "*":
                operands.push(a * b);
                break;
            case "/":
                if (b == 0) {
                    throw new ArithmeticException("Division by zero");
                }
                operands.push(a / b);
                break;
            case "^":
                operands.push(Math.pow(a, b));
                break;
        }
    }

    private int precedence(String operator) {
        switch (operator) {
            case "^":
                return 3;
            case "*":
            case "/":
                return 2;
            case "+":
            case "-":
                return 1;
            default:
                return 0;
        }
    }

    public static void main(String[] args) {
        ScientificCalculator calculator = new ScientificCalculator();
        calculator.setVisible(true);
    }

}

这个代码实现了一个带有文本框、计算按钮和输出标签的GUI界面，当用户点击计算按钮时，程序将会调用 `evaluate` 方法来计算用户输入的表达式，并将结果显示在输出标签中。`evaluate` 方法使用了逆波兰表达式算法来解析和计算表达式，同时处理了除数为零等错误情况。