利用JAVA编写一个简单的单选窗口计算器

以下是一个简单的单选窗口计算器的JAVA代码，它可以进行加、减、乘、除四则运算：

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

public class Calculator extends JFrame implements ActionListener {

    private JTextField inputField;
    private JButton addButton, subtractButton, multiplyButton, divideButton, equalsButton, clearButton;
    private double num1, num2;
    private char operator;

    public Calculator() {
        // 设置窗口标题
        setTitle("Calculator");
        // 设置窗口大小
        setSize(300, 300);
        // 设置窗口位置
        setLocationRelativeTo(null);
        // 设置窗口关闭按钮操作
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 创建输入框
        inputField = new JTextField(20);
        inputField.setEditable(false);

        // 创建按钮
        addButton = new JButton("+");
        subtractButton = new JButton("-");
        multiplyButton = new JButton("*");
        divideButton = new JButton("/");
        equalsButton = new JButton("=");
        clearButton = new JButton("C");

        // 添加按钮事件监听器
        addButton.addActionListener(this);
        subtractButton.addActionListener(this);
        multiplyButton.addActionListener(this);
        divideButton.addActionListener(this);
        equalsButton.addActionListener(this);
        clearButton.addActionListener(this);

        // 创建面板并添加组件
        JPanel panel = new JPanel(new GridLayout(4, 2));
        panel.add(inputField);
        panel.add(addButton);
        panel.add(subtractButton);
        panel.add(multiplyButton);
        panel.add(divideButton);
        panel.add(equalsButton);
        panel.add(clearButton);

        // 将面板添加到窗口中
        add(panel);

        // 显示窗口
        setVisible(true);
    }

    // 按钮事件处理方法
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == addButton) {
            num1 = Double.parseDouble(inputField.getText());
            operator = '+';
            inputField.setText("");
        } else if (e.getSource() == subtractButton) {
            num1 = Double.parseDouble(inputField.getText());
            operator = '-';
            inputField.setText("");
        } else if (e.getSource() == multiplyButton) {
            num1 = Double.parseDouble(inputField.getText());
            operator = '*';
            inputField.setText("");
        } else if (e.getSource() == divideButton) {
            num1 = Double.parseDouble(inputField.getText());
            operator = '/';
            inputField.setText("");
        } else if (e.getSource() == equalsButton) {
            num2 = Double.parseDouble(inputField.getText());
            double result = 0;
            switch (operator) {
                case '+':
                    result = num1 + num2;
                    break;
                case '-':
                    result = num1 - num2;
                    break;
                case '*':
                    result = num1 * num2;
                    break;
                case '/':
                    result = num1 / num2;
                    break;
            }
            inputField.setText(Double.toString(result));
        } else if (e.getSource() == clearButton) {
            inputField.setText("");
        }
    }

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

运行该程序，将会显示一个带有输入框和按钮的窗口，用户可以在输入框中输入数字，并通过单击按钮执行四则运算。