未显示JList - list的JTextField输入

JFrame frame = new JFrame("JList Example");
JTextField textField = new JTextField();
JList<String> list = new JList<>();

DefaultListModel<String> listModel = new DefaultListModel<>();
list.setModel(listModel);

textField.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        String input = textField.getText();
        listModel.addElement(input);
        textField.setText("");
    }
});

frame.setLayout(new BorderLayout());
frame.add(textField, BorderLayout.NORTH);
frame.add(new JScrollPane(list), BorderLayout.CENTER);
frame.setSize(300, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);