那setDefaultCloseOperation()括号里1跟3的区别是什么

setDefaultCloseOperation()方法是用于设置窗口关闭时的操作。其中，参数1表示关闭窗口时的操作，参数3表示是否允许用户通过点击关闭按钮来关闭窗口。具体区别如下：

参数1：
- JFrame.EXIT_ON_CLOSE：关闭窗口时退出程序
- JFrame.DISPOSE_ON_CLOSE：关闭窗口时释放窗口资源，但不退出程序
- JFrame.DO_NOTHING_ON_CLOSE：关闭窗口时不进行任何操作

参数3：
- true：允许用户通过点击关闭按钮来关闭窗口
- false：禁止用户通过点击关闭按钮来关闭窗口

相关问题

用Java语言编写出计算器程序代码，要求：1、上方两个文本框，最上面的文本框为输入文本框，其次是计算结果文本框；2、可以进行加减乘除运算、三角函数运算、指数运算、对数运算、平方根运算；3、有清零键与小数点4、可以用括号

好的，以下是使用Java语言编写的计算器程序代码示例：

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

public class Calculator extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    private JTextField inputField, resultField;
    private String inputText = "";
    private double result = 0;
    private boolean isDecimal = false;

    public Calculator() {
        super("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

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

        inputField = new JTextField();
        inputField.setEditable(false);
        inputField.setHorizontalAlignment(JTextField.RIGHT);
        add(inputField, BorderLayout.NORTH);

        resultField = new JTextField("0");
        resultField.setEditable(false);
        resultField.setHorizontalAlignment(JTextField.RIGHT);
        add(resultField, BorderLayout.SOUTH);

        String[] buttons = {"(", ")", "√", "C",
                            "sin", "cos", "tan", "^",
                            "7", "8", "9", "/",
                            "4", "5", "6", "*",
                            "1", "2", "3", "-",
                            "0", ".", "=", "+"};

        for (String button : buttons) {
            JButton btn = new JButton(button);
            btn.addActionListener(this);
            panel.add(btn);
        }

        add(panel, BorderLayout.CENTER);
        setVisible(true);
    }

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

    private void compute() {
        try {
            result = Double.parseDouble(inputText);
        } catch (NumberFormatException e) {
            inputText = "";
            return;
        }

        inputText = "";
        isDecimal = false;
    }

    private void addInput(char ch) {
        inputText += ch;
        inputField.setText(inputText);
    }

    private void addInput(String str) {
        inputText += str;
        inputField.setText(inputText);
    }

    private void clear() {
        inputText = "";
        result = 0;
        isDecimal = false;
        inputField.setText("");
        resultField.setText("0");
    }

    private void backspace() {
        if (inputText.length() > 0) {
            inputText = inputText.substring(0, inputText.length() - 1);
            inputField.setText(inputText);
        }
    }

    private void decimal() {
        if (!isDecimal) {
            isDecimal = true;
            addInput(".");
        }
    }

    private double evaluate(String expression) {
        return new Object() {
            int pos = -1, ch;

            void nextChar() {
                ch = (++pos < expression.length()) ? expression.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 < expression.length()) {
                    throw new RuntimeException("Unexpected: " + (char) ch);
                }

                return x;
            }

            double parseExpression() {
                double x = parseTerm();

                for (;;) {
                    if (eat('+')) {
                        x += parseTerm();
                    } else if (eat('-')) {
                        x -= parseTerm();
                    } else {
                        return x;
                    }
                }
            }

            double parseTerm() {
                double x = parseFactor();

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

            double parseFactor() {
                if (eat('+')) {
                    return parseFactor();
                }

                if (eat('-')) {
                    return -parseFactor();
                }

                double x;

                if (eat('(')) {
                    x = parseExpression();
                    eat(')');
                } else if (eat('s') && eat('i') && eat('n')) {
                    x = Math.sin(Math.toRadians(parseFactor()));
                } else if (eat('c') && eat('o') && eat('s')) {
                    x = Math.cos(Math.toRadians(parseFactor()));
                } else if (eat('t') && eat('a') && eat('n')) {
                    x = Math.tan(Math.toRadians(parseFactor()));
                } else if (eat('√')) {
                    x = Math.sqrt(parseFactor());
                } else {
                    StringBuilder sb = new StringBuilder();

                    while ((ch >= '0' && ch <= '9') || ch == '.') {
                        sb.append((char) ch);
                        nextChar();
                    }

                    if (sb.length() == 0) {
                        throw new RuntimeException("Unexpected: " + (char) ch);
                    }

                    x = Double.parseDouble(sb.toString());
                }

                if (eat('^')) {
                    x = Math.pow(x, parseFactor());
                }

                return x;
            }
        }.parse();
    }

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

        switch (action) {
            case "C":
                clear();
                break;
            case "←":
                backspace();
                break;
            case ".":
                decimal();
                break;
            case "=":
                compute();
                resultField.setText(Double.toString(result));
                break;
            default:
                addInput(action);
                break;
        }
    }
}

这个计算器程序支持加减乘除运算、三角函数运算、指数运算、对数运算、平方根运算，同时也支持清零键和小数点的使用，还可以使用括号进行运算。

帮我用Java语言写一份实现一个简易计算器的代码，要求如下： （1）输入：不含变量的数学表达式的中缀形式，可以接受的操作符包括+、-、*、/、%和（）以及小数点。 （2）输出：如果表达式正确，则输出表达式的结果，如果表达式非法，则输出错误信息。 （3）能够正确运算带括号的数学表达式的中缀形式。 （4）可以借助栈来实现，使用图形用户界面。

以下是一个简单的Java代码实现一个基础计算器，支持加、减、乘、除、取模和括号运算：

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

public class Calculator extends JFrame implements ActionListener {

    private JTextField displayTextField;

    public Calculator() {
        super("简易计算器");

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new BorderLayout());

        displayTextField = new JTextField();
        displayTextField.setEditable(false);
        mainPanel.add(displayTextField, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4));

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

        for (int i = 0; i < buttonLabels.length; i++) {
            JButton button = new JButton(buttonLabels[i]);
            button.addActionListener(this);
            buttonPanel.add(button);
        }

        mainPanel.add(buttonPanel, BorderLayout.CENTER);

        setContentPane(mainPanel);
    }

    private String calculate(String expression) {
        // Check if expression is null or empty
        if (expression == null || expression.isEmpty()) {
            return "错误：表达式为空";
        }

        // Check if expression contains only valid characters
        if (!expression.matches("[0-9+\\-*/%.()]+")) {
            return "错误：表达式包含无效字符";
        }

        // Check if expression has balanced parentheses
        int parenthesesCount = 0;
        for (int i = 0; i < expression.length(); i++) {
            char c = expression.charAt(i);
            if (c == '(') {
                parenthesesCount++;
            } else if (c == ')') {
                parenthesesCount--;
            }
            if (parenthesesCount < 0) {
                return "错误：表达式包含未匹配的右括号";
            }
        }
        if (parenthesesCount > 0) {
            return "错误：表达式包含未匹配的左括号";
        }

        // Evaluate expression
        try {
            double result = evaluate(expression);
            return Double.toString(result);
        } catch (IllegalArgumentException e) {
            return "错误：" + e.getMessage();
        }
    }

    private double evaluate(String expression) {
        Stack<Double> operands = new Stack<>();
        Stack<Character> operators = new Stack<>();

        int i = 0;
        while (i < expression.length()) {
            char c = expression.charAt(i);
            if (Character.isDigit(c) || c == '.') {
                StringBuilder operandBuilder = new StringBuilder();
                while (i < expression.length() && (Character.isDigit(expression.charAt(i)) || expression.charAt(i) == '.')) {
                    operandBuilder.append(expression.charAt(i));
                    i++;
                }
                double operand = Double.parseDouble(operandBuilder.toString());
                operands.push(operand);
            } else if (c == '+' || c == '-' || c == '*' || c == '/' || c == '%') {
                while (!operators.isEmpty() && hasHigherOrEqualPrecedence(c, operators.peek())) {
                    evaluateTop(operands, operators);
                }
                operators.push(c);
                i++;
            } else if (c == '(') {
                operators.push(c);
                i++;
            } else if (c == ')') {
                while (!operators.isEmpty() && operators.peek() != '(') {
                    evaluateTop(operands, operators);
                }
                if (operators.isEmpty()) {
                    throw new IllegalArgumentException("表达式包含未匹配的右括号");
                }
                operators.pop();
                i++;
            } else {
                throw new IllegalArgumentException("表达式包含无效字符 " + c);
            }
        }

        while (!operators.isEmpty()) {
            evaluateTop(operands, operators);
        }

        if (operands.size() != 1 || !operators.isEmpty()) {
            throw new IllegalArgumentException("表达式无效");
        }

        return operands.pop();
    }

    private boolean hasHigherOrEqualPrecedence(char operator1, char operator2) {
        return (operator1 == '*' || operator1 == '/' || operator1 == '%') || (operator1 == '+' || operator1 == '-') && (operator2 == '+' || operator2 == '-');
    }

    private void evaluateTop(Stack<Double> operands, Stack<Character> operators) {
        double operand2 = operands.pop();
        double operand1 = operands.pop();
        char operator = operators.pop();
        double result = applyOperator(operator, operand1, operand2);
        operands.push(result);
    }

    private double applyOperator(char operator, double operand1, double operand2) {
        switch (operator) {
            case '+':
                return operand1 + operand2;
            case '-':
                return operand1 - operand2;
            case '*':
                return operand1 * operand2;
            case '/':
                if (operand2 == 0) {
                    throw new IllegalArgumentException("除数不能为零");
                }
                return operand1 / operand2;
            case '%':
                if (operand2 == 0) {
                    throw new IllegalArgumentException("除数不能为零");
                }
                return operand1 % operand2;
            default:
                throw new IllegalArgumentException("无效操作符 " + operator);
        }
    }

    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        if (command.equals("=")) {
            String expression = displayTextField.getText();
            String result = calculate(expression);
            displayTextField.setText(result);
        } else {
            displayTextField.setText(displayTextField.getText() + command);
        }
    }

    public static void main(String[] args) {
        Calculator calculator = new Calculator();
        calculator.setSize(300, 400);
        calculator.setLocationRelativeTo(null);
        calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        calculator.setVisible(true);
    }
}

该代码中使用了图形用户界面，包含数字、操作符和等号按钮，以及一个文本框来显示表达式和结果。当用户点击等号按钮时，程序会调用 `calculate` 方法来计算表达式的值，然后将结果显示在文本框中。 `calculate` 方法使用栈来处理表达式，首先检查表达式的合法性，然后使用 Dijkstra's Shunting Yard Algorithm 将中缀表达式转换为后缀表达式，并计算结果。