使用GroupLayout布置的面板使scrollRectToVisible起作用

Question

A rather minimal example: This lays out a JLabel in a JPanel , stuffs the JPanel into a JScrollPane , and sticks that in a JFrame . I then want the pane to scroll so as to make the JLabel visible, but it does not do so. I've tried calling scrollRectToVisible on the label and the panel, with no luck, messed around with viewports, with no luck, tried setting scrollbar values manually, with no luck. Clearly I'm doing something stupid, but I can't see what.

import java.awt.Dimension;
import java.awt.Rectangle;

import javax.swing.*;

public class SillyTest {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JPanel panel = new JPanel();
                GroupLayout layout = new GroupLayout(panel);
                panel.setLayout(layout);
                GroupLayout.SequentialGroup seq = layout
                        .createSequentialGroup();
                GroupLayout.ParallelGroup par = layout.createParallelGroup();
                JLabel fish = new JLabel("fish");
                seq.addGap(3000);
                seq.addComponent(fish);
                par.addComponent(fish);
                par.addGap(200);
                layout.setHorizontalGroup(par);
                layout.setVerticalGroup(seq);
                JScrollPane scrollPane = new JScrollPane(panel);
                JFrame frame = new JFrame("whatever this is about");
                frame.add(scrollPane);
                frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
                frame.pack();
                frame.setVisible(true);
                fish.scrollRectToVisible(fish.getBounds());
            }
        });
    }
}

Answer 1

Code works fine for me using JDK7 on Windows7.

If you have an issue on a different version then you can try:

SwingUtilities.invokeLater(new Runnable()
{
    public void run()
    {
        fish.scrollRectToVisible(fish.getBounds());
    }
});

This just makes sure the scrollRectToVisible() is added to the end of the EDT so it should be processed after all the initial logic to display the frame has occurred.