JScrollPane打开到面板的底部

Question

I have a JScrollPane on a panel (which has many panels inside of it) and when I open the frame with the scroll pane on it, the fame is scrolled to the bottom. Is there anyway I can avoid this?

Here are some facts:

• The panel the scroller is on contains multiple panels. Some of these panels have text fields. I have tried to set the carat of the text fields to 0 and this did not work.

• I know there should be actual code, but when I tried to make a mock pane (as the one I am using is intertwined with a lot of code) it is not replicating the issue.

• The panel that is being scrolled is being generated using a loop that generates a series of questions... so a text box, a said amount of buttons/answers, and a text box and label that shows the amount of points for each question.

• The last elements of my panel that is being scrolled are a JTextArea and a JLabel. Below is the code to declare those.

Is there anyone out there that could at least throw out an idea of what would be making the scroll pane automatically go to the bottom?

Here is the declaration of the pane and the panels inside/outside of it

JPanel newPanel = new JPanel(new BorderLayout(0, 0));
    JPanel showPanel = new JPanel();
    BoxLayout layout = new BoxLayout(showQuizPanel, BoxLayout.Y_AXIS);
    showQuizPanel.setLayout(layout);
    buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
    buttonPanel.setBackground(Color.white);
    newPanel.setBackground(Color.white);
    showPanel.setBackground(Color.white);
    populateButtonPanel();
    populateShowPanel(showPanel, buttonPanel);
    populateQuestions(showPanel);

    JScrollPane scrollPane = new JScrollPane(showPanel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    scrollPane.getViewport().setBackground(Color.WHITE);
    scrollPane.setAlignmentX(JScrollPane.CENTER_ALIGNMENT);
    scrollPane.getVerticalScrollBar().setUnitIncrement(16);
    scrollPane.getVerticalScrollBar().setValue(0);
    scrollPane.getViewport().setViewPosition(new Point(0,0));

    newPanel.add(scrollPane, BorderLayout.CENTER);
    return newPanel;

code to declare last elements on page

JPanel pPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
pPanel.setBackground(Color.WHITE);
pPanel.add(qValue);
pPanel.add(new JLabel("Points"));
qArea.add(pPanel);
qArea.add(Box.createVerticalStrut(50));
qValue.setCaretPosition(0);

Thanks!

Answer 1

I believe that when you add text to a text area when building the GUI, the scroll pane will scroll to make the text area visible.

So basically you need to reset the scroll pane to the top.

You can use code like the following after adding all components to the scroll pane:

SwingUtilities.invokeLater(new Runnable()
{
    public void run()
    {
        scrollPane.getViewport().setViewPosition( new Point(0, 0) );
    }
});

The invokeLater() adds the code to the end of the Event Dispatch Thread (EDT) so that it gets executed after the GUI is visible.

Of course this code assumes that you are creating the rest of the GUI properly on the EDT.