Scrollbars aren't appear in JLabel with huge image size.

Question

I use Jlabel to show image, but i have a problem with scrollbars now. Scrollbars don't appear. Let's I show my code:

   public AVFrame(String title, ArrayList<String> imageList) throws HeadlessException {
    super(title);
    this.imageList = imageList;

    AddRootPanel(imageList);

    //Config frame
    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    setSize(FRAME_WIDTH, FRAME_HEIGHT);
    addWindowListener(new WindowAdapter() {
        /**
         * Invoked when a window is in the process of being closed.
         * The close operation can be overridden at this point.
         */
        @Override
        public void windowClosing(WindowEvent e) {
            rp.stopListening();
            System.exit(0);
        }
    });

    //pack();
    //setResizable(false);
    setLocationRelativeTo(null); // center the window
    setVisible(true);
}

/**
 * Method add root panel into frame
 */
private void AddRootPanel(ArrayList<String> imageList) {
    rp = new RootPanel(imageList);
    Container container = getContentPane();
    container.add(rp);
}
    **
 * Creates a new <code>JPanel</code> with a double buffer
 * and a flow layout.
 */
public RootPanel(ArrayList imageList) {

    this.imageList = imageList;
    listener = new AVListener(this);
    controller = new Controller();
    controller.addListener(listener);

    addImageLabel();
    showImage((File) this.imageList.get(0));
}

private void addImageLabel() {
    imgLabel = new JLabel();
    JScrollPane scrollPane = new JScrollPane(imgLabel);
    scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
    scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    add(scrollPane);
}

public  void showImage(File imagePath) {
    try {
        bufferedImage = ImageIO.read(imagePath);
    } catch (IOException e) {
        e.printStackTrace();
    }
    ImageIcon icon = new ImageIcon(bufferedImage);
    imgLabel.setIcon(icon);

If anyone need my code see: https://github.com/VitaliyPetrov/AIR_WORK/tree/master/Air%20Viewer

P.S. My global idea is create app, that will be can resize, rotate images. If anyone, have suggestions or tips how improve my code. I'll be thankful.

Answer 1

Add JScrollPane directly into the JFrame's Content Pane instead of adding JScrollPane first into JPanel.

Do in this way

private void AddRootPanel(ArrayList<String> imageList) {
   rp = new RootPanel(imageList);
   Container container = getContentPane();
   container.add(rp.getScrollpane());
}

// Not require to extend JPanel for RootPanel class if it contains only single component
class RootPanel{
    private JScrollPane scrollpane;
    ...
    private void addImageLabel() {
        imgLabel = new JLabel();
        scrollPane= new JScrollPane(imgLabel);
        ...
    }
    public JScrollPane  getScrollpane(){
        return scrollPane;
    }
}