JScrollPane does not work with JTextArea

i create a little pop-up window. I have 2 input which are JTextField and JTextArea. I added JScrollPane to JTextArea. When i run to program, scrollpane is seen. But i couldnt use it. I share the image how it look like. I think i have to add height but i dont know what height

public class AddCommentDialog extends JDialog implements ShowableDialog, ActionListener {

    private static final long serialVersionUID = 1L;
    private static JTextField inputTitle = new JTextField();
    private static JTextArea inputComment = new JTextArea();
    private Rectangle rectangle = new Rectangle();
    private JLabel lblTitle = new JLabel("Başlık: ");
    private JLabel lblComment = new JLabel("Yorum: ");
    private JButton buttonSave = new JButton(" Kaydet ");
    private JButton buttonCancel = new JButton(" İptal ");

    // Kullanıcı tarafından girilen başlık ve yorum
    private String title, comment;


    /**
     * The constructor that sets the fields and the dialog.
     */
    public AddCommentDialog() {

        super(ImageViewerGui.getMainFrame(), "Yorum Ekle", true);

        JPanel panel = new JPanel(new BorderLayout(5, 5));
        // the input text fields
        JPanel northContainer = new JPanel(new BorderLayout(7, 7));

        JPanel labelPanel = new JPanel(new BorderLayout(5, 5));
        JPanel fieldPanel = new JPanel(new BorderLayout(5, 5));

        // the buttons
        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));

        buttonSave.addActionListener(this);
        buttonCancel.addActionListener(this);
        inputTitle.setPreferredSize(new Dimension(250, 25));
        inputComment.setPreferredSize(new Dimension(250, 75));
        buttonSave.setPreferredSize(new Dimension(90, 25));
        buttonCancel.setPreferredSize(new Dimension(90, 25));

        // Satır bitince alt satıra inmesi için
        inputComment.setLineWrap(true);
        JScrollPane scrollCommentArea = new JScrollPane(inputComment);
        scrollCommentArea.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

        try {

            labelPanel.add(lblTitle, BorderLayout.NORTH);
            labelPanel.add(lblComment, BorderLayout.CENTER);

            fieldPanel.add(inputTitle, BorderLayout.NORTH);
            fieldPanel.add(scrollCommentArea, BorderLayout.CENTER);
            buttonPanel.add(buttonCancel);
            buttonPanel.add(buttonSave);

            northContainer.add(labelPanel, BorderLayout.WEST);
            northContainer.add(fieldPanel, BorderLayout.CENTER);
            panel.add(northContainer, BorderLayout.NORTH);
            panel.add(buttonPanel, BorderLayout.SOUTH);
            panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
            inputTitle.setText("");
            inputComment.setText("");
            add(panel);
            this.setResizable(true);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

Solution

static is going to a potential issue, but inputComment.setPreferredSize(new Dimension(250, 75)); is definitely part of your core problem. Use setRows and setColumns instead.

inputComment.setRows(4);
inputComment.setColumns(38);

The basic problem is, JScrollPane relies on the components preferred size to determine if it should show the scroll bars or not (or if they actually do anything)