如何使用流检查所有JComponents是否为空

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

public class ComponentChecker {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Component Checker");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 300);

        // 创建一个面板
        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout());

        // 添加一些组件到面板中
        panel.add(new JLabel("Label"));
        panel.add(new JTextField(10));
        panel.add(new JButton("Button"));
        panel.add(new JCheckBox("Checkbox"));
        panel.add(new JRadioButton("Radio Button"));

        // 检查所有组件是否为空
        checkComponents(panel);

        // 将面板添加到框架中
        frame.getContentPane().add(panel);
        frame.setVisible(true);
    }

    public static void checkComponents(Container container) {
        Component[] components = container.getComponents();
        for (Component component : components) {
            if (component instanceof JComponent) {
                if (component instanceof Container) {
                    checkComponents((Container) component);
                }
                if (component instanceof JTextComponent) {
                    JTextComponent textComponent = (JTextComponent) component;
                    if (textComponent.getText().isEmpty()) {
                        System.out.println("Text component is empty: " + component.getName());
                    }
                } else if (component instanceof JComboBox) {
                    JComboBox comboBox = (JComboBox) component;
                    if (comboBox.getSelectedItem() == null) {
                        System.out.println("Combo box is empty: " + component.getName());
                    }
                } else if (component instanceof JList) {
                    JList list = (JList) component;
                    if (list.getSelectedValue() == null) {
                        System.out.println("List is empty: " + component.getName());
                    }
                } else if (component instanceof JTable) {
                    JTable table = (JTable) component;
                    if (table.getRowCount() == 0) {
                        System.out.println("Table is empty: " + component.getName());
                    }
                } else if (component instanceof JTree) {
                    JTree tree = (JTree) component;
                    if (tree.getSelectionCount() == 0) {
                        System.out.println("Tree is empty: " + component.getName());
                    }
                }
            }
        }
    }
}