窗体完成Java的加减乘除功能

好的，我可以为您提供一个简单的Java窗体实现加减乘除功能的示例代码。您可以在窗体中输入数字和操作符，然后点击“=”按钮得到计算结果。以下是示例代码：

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

public class Calculator extends JFrame implements ActionListener {
    private JTextField textField;
    private JButton button0, button1, button2, button3, button4,
            button5, button6, button7, button8, button9, buttonAdd,
            buttonSub, buttonMul, buttonDiv, buttonDot, buttonEqual,
            buttonClear, buttonBackspace;

    private double num1 = 0.0, num2 = 0.0;
    private String operator = "";

    public Calculator() {
        setTitle("Calculator");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        setSize(250, 300);
        setLocationRelativeTo(null);

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

        textField = new JTextField(20);
        textField.setEditable(false);
        panel.add(textField);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        add(panel);
        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == buttonClear) {
            num1 = 0.0;
            num2 = 0.0;
            operator = "";
            textField.setText("");
        } else if (e.getSource() == buttonBackspace) {
            String text = textField.getText();
            if (!text.isEmpty()) {
                text = text.substring(0, text.length() - 1);
                textField.setText(text);
            }
        } else if (e.getSource() == buttonAdd || e.getSource() == buttonSub
                || e.getSource() == buttonMul || e.getSource() == buttonDiv) {
            num1 = Double.parseDouble(textField.getText());
            operator = e.getActionCommand();
            textField.setText("");
        } else if (e.getSource() == buttonEqual) {
            num2 = Double.parseDouble(textField.getText());
            double result = 0.0;
            switch (operator) {
                case "+":
                    result = num1 + num2;
                    break;
                case "-":
                    result = num1 - num2;
                    break;
                case "*":
                    result = num1 * num2;
                    break;
                case "/":
                    if (num2 == 0) {
                        JOptionPane.showMessageDialog(this, "Cannot divide by zero!", "Error", JOptionPane.ERROR_MESSAGE);
                        return;
                    } else {
                        result = num1 / num2;
                        break;
                    }
            }
            textField.setText(String.valueOf(result));
        } else {
            textField.setText(textField.getText() + e.getActionCommand());
        }
    }

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

这个程序实现了基本的加、减、乘、除运算，以及清空输入框、删除最后一个字符等功能。您可以根据需要自行扩展。