Java Swing：JRadioButton 选中项转换为字符串的正确姿势

categorystring = group.getSelection().toString();

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.*;
import javax.swing.event.ChangeEvent; // 导入 ChangeEvent
import javax.swing.event.ChangeListener; // 导入 ChangeListener

@SuppressWarnings("serial")
public class JRadioButtonSelectionExample extends JPanel {
    private static final String[] BUTTON_TEXTS = {"星期一", "星期二", "星期三", "星期四", "星期五"};
    private ButtonGroup buttonGroup = new ButtonGroup();
    private JTextField resultField = new JTextField(15); // 增加文本框宽度

    public JRadioButtonSelectionExample() {
        // 结果显示面板
        JPanel topPanel = new JPanel();
        topPanel.add(new JLabel("当前选择:"));
        topPanel.add(resultField);
        resultField.setFocusable(false); // 禁止用户直接编辑

        // 单选按钮面板
        JPanel radioPanel = new JPanel(new GridLayout(0, 1)); // 垂直排列
        for (String buttonText : BUTTON_TEXTS) {
            JRadioButton radioBtn = new JRadioButton(buttonText);
            // 关键步骤1: 为JRadioButton设置动作命令
            radioBtn.setActionCommand(buttonText);

            // 添加ChangeListener来实时更新结果
            radioBtn.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    // 关键步骤2: 获取ButtonModel并从中获取动作命令
                    ButtonModel buttonModel = buttonGroup.getSelection();
                    if (buttonModel != null) { // 确保有选中项
                        String selectedText = buttonModel.getActionCommand();
                        resultField.setText(selectedText);
                    } else {
                        resultField.setText("无选择"); // 如果没有选中项
                    }
                }
            });

            radioPanel.add(radioBtn);
            buttonGroup.add(radioBtn); // 将按钮添加到ButtonGroup
        }

        // 布局主面板
        setLayout(new BorderLayout());
        add(topPanel, BorderLayout.PAGE_START);
        add(radioPanel, BorderLayout.CENTER);
    }

    public static void main(String[] args) {
        // 在事件分发线程中创建和显示GUI
        SwingUtilities.invokeLater(() -> {
            JRadioButtonSelectionExample mainPanel = new JRadioButtonSelectionExample();

            JFrame frame = new JFrame("JRadioButton 选中项获取示例");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(mainPanel);
            frame.pack(); // 根据组件的首选大小调整窗口大小
            frame.setLocationRelativeTo(null); // 窗口居中显示
            frame.setVisible(true);
        });
    }
}