Panel sizing issues! IT'S TOO BIG FOR IT'S BOOTS!!!!!

Question

Hi there,
I have a Panel which I make the client of a ScrollPane. The ScrollPane is added onto a container. This is all fine. My challenge is that I have about eighteen components (labels - containing pictures, text areas, etc) on the one panel. The panel is set to BoxLayout (up and down style) which results in all the components being stacked one on top of the next. When the program runs the scrollPane is fine, and it has bars both horizontally and vertically. Ideally however I only want to have vertical scrollbars and no horizontal scrollbars because I want my content to be the width of the onscreen window. If I force the scrollPane's horizontal bar off then I can only see some of the content on the Panel because the Panel still takes up heaps of room. I have learned from this that it is not possible to control the size of the component that is the client of the scrollPane by playing with the scroll bars.
I figured the only logical way to get around my challenge is to control the size of the panel before it is made the client of the scrollPane. I set the size of the Panel explicitly with setSize(value1, value2) however the Panel still takes up a huge screen area.
Basically trying to explicitly set the Panel failed, the code compiled but there was no desirable outcomes. I really want to work out how to force the Panel to be a given size and then use only one scroll bar on the scrollPane. I figure that this is an issue related to BoxLayout, but I may be well of track with that hypothesis. My code is provided below if anybody can offer any clues they will be greatly appreciated.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HelpGUI extends JFrame implements ActionListener
  HelpGUI()
    Toolkit tk = Toolkit.getDefaultToolkit();
    Dimension sSize = tk.getScreenSize();
    /* Fonts created here. */
    Font mainhead = new Font("Tahoma",Font.BOLD,22);
    Font subhead = new Font("Arial Black",Font.PLAIN,16);
    /* Images and there associated accomodations (labels) */
    ImageIcon pic1 = new ImageIcon("Images/launch1a.jpg");
    ImageIcon pic2 = new ImageIcon("Images/launch1b.jpg");
    ImageIcon pic3 = new ImageIcon("Images/launch1c.jpg");
    ImageIcon pic5 = new ImageIcon("Images/launch1e.jpg");
    ImageIcon pic6 = new ImageIcon("Images/launch1f.jpg");
    ImageIcon pic7 = new ImageIcon("Images/launch1g.jpg");
    ImageIcon pic8 = new ImageIcon("Images/launch1h.jpg");
    ImageIcon pic9 = new ImageIcon("Images/launch1i.jpg");
    ImageIcon pic10 = new ImageIcon("Images/launch1j.jpg");
    ImageIcon pic11 = new ImageIcon("Images/launch1k.jpg");
    ImageIcon pic12 = new ImageIcon("Images/launch1l.jpg");
    ImageIcon pic13 = new ImageIcon("Images/launch1m.jpg");
    JLabel icon1 = new JLabel("",pic1,JLabel.LEFT);
    JLabel icon2 = new JLabel("",pic2,JLabel.LEFT);
    JLabel icon3 = new JLabel("",pic3,JLabel.LEFT);
    JLabel icon5 = new JLabel("",pic5,JLabel.LEFT);
    JLabel icon6 = new JLabel("",pic6,JLabel.LEFT);
    JLabel icon7 = new JLabel("",pic7,JLabel.LEFT);
    JLabel icon8 = new JLabel("",pic8,JLabel.LEFT);
    JLabel icon9 = new JLabel("",pic9,JLabel.LEFT);
    JLabel icon10 = new JLabel("",pic10,JLabel.LEFT);
    JLabel icon11 = new JLabel("",pic11,JLabel.LEFT);
    JLabel icon12 = new JLabel("",pic12,JLabel.LEFT);
    //Labels containing strings.
    JLabel heading = new JLabel("INSTRUCTIONS",JLabel.LEFT);
    heading.setFont(mainhead);
    JLabel addhead = new JLabel("Adding a shortcut to the toolbar.");
    addhead.setFont(subhead);
    JLabel delhead = new JLabel("Deleting a shortcut from the toolbar.");
    addhead.setFont(subhead);
    /* Text blocks describing program operation, used in conjunction with the
    labels and images instantiated above. */
    JTextArea intro = new JTextArea(
      "This toolbar contains two established shortcut buttons. It also contains "+
      "three empty shortcut buttons. The toolbar can be customised to your exact "+
      "requirements. Please follow the instructions below if you are uncertain of "+
      "how to enter a shortcut. Alternatively you can delete shortcuts from this "+
      "toolbar by following instructions provided further down this page.");
    intro.setLineWrap(true);
    intro.setWrapStyleWord(true);
    intro.setEditable(false);
    //intro.setBackground(this.getBackground());
    JTextArea inst1 = new JTextArea(
      "1). On the File menu click New.");
    inst1.setLineWrap(true);
    inst1.setWrapStyleWord(true);
    inst1.setEditable(false);
    //intro.setBackground(this.getBackground());
    JTextArea inst2 = new JTextArea(
      "2). In the Please Enter Shortcut Details window enter a Shortcut Name "+
      "for the new shortcut.");
    inst2.setLineWrap(true);
    inst2.setWrapStyleWord(true);
    inst2.setEditable(false);
    //inst2.setBackground(this.getBackground());
    JTextArea inst3 = new JTextArea(
      "3). Click on the Open button. This presents the file browser."+
      "4). Select a relevant subdirectory and click the Open button.");
    inst3.setLineWrap(true);
    inst3.setWrapStyleWord(true);
    inst3.setEditable(false);
    //inst3.setBackground(this.getBackground());
    JTextArea inst5 = new JTextArea(
      "5). Repeat step 4 if necessary.");
    inst5.setLineWrap(true);
    inst5.setWrapStyleWord(true);
    inst5.setEditable(false);
    //inst5.setBackground(this.getBackground());
    JTextArea inst6 = new JTextArea(
      "6). Repeat step 4 if necessary.");
    inst6.setLineWrap(true);
    inst6.setWrapStyleWord(true);
    inst6.setEditable(false);
    //inst6.setBackground(this.getBackground());
    JTextArea inst7 = new JTextArea(
      "7). Select the required executable file and press the Open button.");
    inst7.setLineWrap(true);
    inst7.setWrapStyleWord(true);
    inst7.setEditable(false);
    //inst7.setBackground(this.getBackground());
    JTextArea inst8 = new JTextArea(
      "8). Press the Ok button.");
    inst8.setLineWrap(true);
    inst8.setWrapStyleWord(true);
    inst8.setEditable(false);
    //inst8.setBackground(this.getBackground());
    JButton exitbtn = new JButton("Exit");
    JPanel panel = new JPanel();
    panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
    //panel.setSize(sSize.width*14/17,sSize.height*9/10);
    panel.setBackground(Color.CYAN);
    panel.add(heading);          //"INSTRUCTIONS" heading.
    panel.add(icon1);            //First picture of toolbar.
    panel.add(intro);            //First text block.
    panel.add(addhead);          //"Adding a shortcut ..." heading.
    panel.add(inst1);            //First instruction 1).
    panel.add(icon2);            //Picture for 1).
    panel.add(inst2);            //Second instruction 2).
    panel.add(icon5);            //Picture of 2).
    panel.add(inst3);            //3). and 4).
    panel.add(icon6);            //Picture for 3 and 4.
    panel.add(inst5);            //5).
    panel.add(icon7);            //Picture for instruction 5).
    panel.add(inst6);            //6).
    panel.add(icon8);            //Picture for instruction 6).
    panel.add(inst7);            //7).
    panel.add(icon9);            //Pic 7).
    panel.add(inst8);            //8).
    panel.add(icon10);           //Pic 8).
    Container c = getContentPane();
    JScrollPane scrollPane = new JScrollPane(panel);
    scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    //scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    c.add(scrollPane);
    setLocation(sSize.width*18/100,sSize.height*1/20);
    setSize(sSize.width*14/17,sSize.height*9/10);
    setTitle("Java QuickLaunch Toolbar");
    setVisible(true);
  public void actionPerformed(ActionEvent e)
}Thanks heaps

Answer 1

Interestingly enough, the preferredLayoutSize method of the layout manager attached to the JScrollPane never gets called when the scroll pane is resized horizontally, only vertically. I found this out by subclassing BoxLayout so that it printed a string when certain methods were called. I did that after noticing that I can resize your help window vertically with no problem, but horizontally is a different story -- when I increase the horizontal size, the JPanel grows to fit, but when I decrease the horizontal size, the JPanel stays the same size. Returning smaller Dimensions in preferredLayoutSize of my overrided BoxLayout class didn't help.
I investigated further and subclassed JPanel to print a message when setSize or setBounds was called. When I vertically resized the help window, JPanel.setBounds was called to resize the JPanel. I was expecting that. However, when I horizontally resized the help window, the JPanel size wasn't updated... at least not in the way I expected it to be. When I increased the horizontal size past the maximum horizontal size so far, the JPanel's horizontal size was increased to match. However, when I decreased the horizontal size, the JPanels horizontal size was not decreased to match.
So, here's what I found:
1) JScrollPane vertical size increased: Scrolled component vertical size increases to match.
2) JScrollPane vertical size decreased: Scrolled component vertical size decreases to match.
3) JScrollPane horizontal size increased: Scrolled component horizontal size increases to match.
4) JScrollPane horizontal size decreased: Scrolled component horizontal does not change.
So the scrolled component horizontal size gets increased, but never decreased. This is odd... perhaps it is a JScrollPane bug? I'll see if I can't figure out a way around it. Overriding the scroll pane's setBounds and setSize methods didn't work, perhaps I'll target the JViewport next.
Sorry I couldn't help right away, though. Lemme know if you figure it out.