java - 将JScrollBar添加到JTextArea

我正在尝试制作一个GUI服务器到客户端消息程序。我写了网络端，那与问题无关。我正在尝试使用JScrollBar使JTextArea滚动。我该怎么做？这是我给客户端的代码（大部分网络代码已删除）：

public class MyClient extends JFrame
{

    public Client client;
    public static Scanner scanner;
    public JTextField textField;
    public JLabel label;
    public static String string;
    public static JTextArea textArea;
    public String username;
    public JScrollBar scrollBar;
    public JScrollPane scrollPane;

    public MyClient()
    {
        setTitle("Client");
        setSize(800, 600);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLayout(new FlowLayout());
        textArea = new JTextArea("");
        scrollBar = new JScrollBar();
        label = new JLabel("Please enter your message");
        add(label);
        textField = new JTextField(70);
        add(textField);
        textField.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                textArea.append(username + ": " + textField.getText() + "\n");                  textField.setText(null);
            }
        });

        add(textArea);
        add(scrollBar, BorderLayout.EAST);
        string = textField.getText();
        scanner = new Scanner(System.in);
    }

     class MyAdjustmentListener implements AdjustmentListener
     {

            public void adjustmentValueChanged(AdjustmentEvent e)
            {
               label.setText("    New Value is " + e.getValue() + "      ");
               repaint();
            }
        }

    public static void main(String[] args) throws IOException
    {
        SwingUtilities.invokeLater(new Runnable()
        {

            @Override
            public void run()
            {
                MyClient myClient = new MyClient();
                myClient.setVisible(true);
                myClient.setResizable(false);
            }

        });
    }
}

最佳答案

您需要一个JScrollPane而不是JScrollBar，请尝试以下代码：

JTextArea textArea = new JTextArea ("");

JScrollPane scroll = new JScrollPane (textArea,
   JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

在上面的代码中，您正在为textArea分配ScrollPane并使它滚动vertically和horizontally。

另一种方法是，创建包含TextArea的ScrollPane，然后将“ vertical scroll = always”设置为on：

JTextArea textArea= new JTextArea();
JScrollPane scroll= new JScrollPane(textArea);

scroll. setVerticalScrollBarPolicy( JScrollPane. VERTICAL_SCROLLBAR_ALWAYS );

在此处阅读教程：Tutorial Link