Java swing简易计算器

以下一个简单的Java Swing计算器示例代码：

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

public class SimpleCalculator implements ActionListener {

    private JFrame frame;
    private JTextField textField;
    private JButton[] buttons;
    private JPanel buttonPanel;

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

    private double result = 0;
    private String operator = "";
    private boolean startOfNumber = true;

    public SimpleCalculator() {
        frame = new JFrame("Simple Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(250, 200);

        textField = new JTextField();
        textField.setHorizontalAlignment(JTextField.RIGHT);
        textField.setEditable(false);

        buttons = new JButton[buttonLabels.length];
        buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4));

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

        frame.add(textField, BorderLayout.NORTH);
        frame.add(buttonPanel, BorderLayout.CENTER);
        frame.setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        String buttonText = e.getActionCommand();

        if (buttonText.matches("[0-9.]")) {
            if (startOfNumber) {
                textField.setText(buttonText);
                startOfNumber = false;
            } else {
                textField.setText(textField.getText() + buttonText);
            }
        } else {
            if (startOfNumber) {
                if (buttonText.equals("-")) {
                    startOfNumber = false;
                    textField.setText(buttonText);
                } else {
                    operator = buttonText;
                }
            } else {
                double number = Double.parseDouble(textField.getText());
                if (operator.equals("+")) {
                    result += number;
                } else if (operator.equals("-")) {
                    result -= number;
                } else if (operator.equals("*")) {
                    result *= number;
                } else if (operator.equals("/")) {
                    result /= number;
                }
                operator = buttonText;
                textField.setText("" + result);
                startOfNumber = true;
            }
        }
    }

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

该计算器具有基本的加、减、乘、除功能，并且可以处理小数。它还具有一个清除按钮，以便可以清除当前输入的数字。可以通过单击“=”按钮获取结果。