利用JAVA编写一个简单的单选窗口计算器，要求数字通过点击得到，运算符也是通过点击选择

以下是一个简单的单选窗口计算器的JAVA代码，运用了Swing库：

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

public class Calculator extends JFrame implements ActionListener {

    private JTextField num1, num2, result;
    private JButton add, subtract, multiply, divide;

    public Calculator() {
        setTitle("Calculator");
        setSize(400, 180);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new GridLayout(4, 2));

        num1 = new JTextField();
        num2 = new JTextField();
        result = new JTextField();
        result.setEditable(false);

        add = new JButton("+");
        subtract = new JButton("-");
        multiply = new JButton("*");
        divide = new JButton("/");

        add.addActionListener(this);
        subtract.addActionListener(this);
        multiply.addActionListener(this);
        divide.addActionListener(this);

        add(new JLabel("Num1:"));
        add(num1);
        add(new JLabel("Num2:"));
        add(num2);
        add(new JLabel("Result:"));
        add(result);
        add(add);
        add(subtract);
        add(multiply);
        add(divide);
    }

    public void actionPerformed(ActionEvent e) {
        double n1 = Double.parseDouble(num1.getText());
        double n2 = Double.parseDouble(num2.getText());
        double res = 0;

        if (e.getSource() == add) {
            res = n1 + n2;
        } else if (e.getSource() == subtract) {
            res = n1 - n2;
        } else if (e.getSource() == multiply) {
            res = n1 * n2;
        } else if (e.getSource() == divide) {
            res = n1 / n2;
        }

        result.setText(Double.toString(res));
    }

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

这个计算器界面包括两个文本框用于输入数字，一个文本框用于显示结果，以及四个按钮用于选择运算符。每个按钮都绑定了一个事件监听器，点击按钮后会根据选择的运算符计算结果并显示在结果文本框中。