模拟实现一个可视化的简单计算器，至少提供包括加法、减法、乘法、除法等基本操作，希望能支持包括正负号、平方根、清零等其他功能

好的，这是一个简单的GUI程序，需要使用Java Swing库来实现。以下是一个实现的例子：

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

public class Calculator extends JFrame implements ActionListener {
    private JTextField inputField;
    private JLabel resultLabel;
    private double num1, num2;
    private String operator;

    public Calculator() {
        // 设置窗口属性
        setTitle("计算器");
        setSize(300, 300);
        setLocationRelativeTo(null);
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 添加组件
        JPanel panel = new JPanel(new GridLayout(5, 4, 5, 5));
        inputField = new JTextField();
        panel.add(inputField);

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

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

        JButton signButton = new JButton("+/-");
        signButton.addActionListener(this);
        panel.add(signButton);

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

        JButton num7Button = new JButton("7");
        num7Button.addActionListener(this);
        panel.add(num7Button);

        JButton num8Button = new JButton("8");
        num8Button.addActionListener(this);
        panel.add(num8Button);

        JButton num9Button = new JButton("9");
        num9Button.addActionListener(this);
        panel.add(num9Button);

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

        JButton num4Button = new JButton("4");
        num4Button.addActionListener(this);
        panel.add(num4Button);

        JButton num5Button = new JButton("5");
        num5Button.addActionListener(this);
        panel.add(num5Button);

        JButton num6Button = new JButton("6");
        num6Button.addActionListener(this);
        panel.add(num6Button);

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

        JButton num1Button = new JButton("1");
        num1Button.addActionListener(this);
        panel.add(num1Button);

        JButton num2Button = new JButton("2");
        num2Button.addActionListener(this);
        panel.add(num2Button);

        JButton num3Button = new JButton("3");
        num3Button.addActionListener(this);
        panel.add(num3Button);

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

        JButton num0Button = new JButton("0");
        num0Button.addActionListener(this);
        panel.add(num0Button);

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

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

        resultLabel = new JLabel();
        panel.add(resultLabel);

        add(panel);
        setVisible(true);
    }

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

        switch (action) {
            case "C":
                clear();
                break;
            case "+/-":
                changeSign();
                break;
            case "√":
                sqrt();
                break;
            case "+":
            case "-":
            case "*":
            case "/":
                setOperator(action);
                break;
            case "=":
                calculate();
                break;
            default:
                appendNumber(action);
        }
    }

    private void clear() {
        inputField.setText("");
        resultLabel.setText("");
        num1 = 0;
        num2 = 0;
        operator = null;
    }

    private void changeSign() {
        String input = inputField.getText();
        if (input.startsWith("-")) {
            inputField.setText(input.substring(1));
        } else {
            inputField.setText("-" + input);
        }
    }

    private void sqrt() {
        String input = inputField.getText();
        double num = Double.parseDouble(input);
        double result = Math.sqrt(num);
        inputField.setText(String.valueOf(result));
    }

    private void setOperator(String op) {
        String input = inputField.getText();
        num1 = Double.parseDouble(input);
        operator = op;
        inputField.setText("");
    }

    private void appendNumber(String num) {
        String input = inputField.getText();
        inputField.setText(input + num);
    }

    private void calculate() {
        String input = inputField.getText();
        num2 = Double.parseDouble(input);
        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;
        }

        resultLabel.setText(String.valueOf(result));
        inputField.setText("");
    }

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

这个程序使用了JFrame和JPanel来创建窗口和组件，并使用了GridLayout来布局组件。使用JTextField和JLabel来实现文本框和标签。实现逻辑是在按钮点击事件中进行相应操作，并将结果显示在标签中。支持的操作包括清零、正负号、平方根、加法、减法、乘法、除法等基本操作。