Setting size JScrollPane inside a JSplitPane

Question

Hi,
In my program I want to have two panels, one above the other. The first panel will contain a row of objects that will be dynamically generated. These objects will have an unchangeable height, which I only know after construction. The second panel, below the first panel, will contain a column of objects, which will also be dynamically generated. These objects will take up almost the screen width.
The following code explains what I am trying to accomplish here.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JSplitPaneProblem extends JPanel
implements ActionListener {
     static Color background;
     static String [] csdEngineers = { "jdoe1", "jdoe2", "jdoe3", "jdoe4", "jdoe5",
          "jdoet", "amacadam" };
     static String [] engineers = { "Choose one", "jdoe1", "jdoe2", "jdoe3", "jdoe4", "jdoe5",
          "jdoet", "amacadam" };
     static int width;
     static int height;
     static int remainingWidth;
     static int insets;
     static int labelWidth;
     static JScrollPane problemPane;
     static JPanel problemPanel;
     static int BIGNUMBER = 1;
     public JSplitPaneProblem () {
          setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS));
          //Get the image to use.
          ImageIcon trafficLight = createImageIcon("trafficlight.gif");
          JLabel trafficLightLabel = new JLabel (trafficLight);
          if (trafficLight != null) {
               width = trafficLight.getIconWidth();
               height = trafficLight.getIconHeight();
          else {
               width = 100;
               height = 300;
          trafficLightLabel.setPreferredSize(new Dimension (width, height + 50));
          //Set up the scroll pane.
          JScrollPane trafficLightPane = new JScrollPane(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER,
                    ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
          JPanel trafficLightPanel = new JPanel();
          trafficLightPanel.setLayout(new BoxLayout(trafficLightPanel, BoxLayout.LINE_AXIS));
          for (int i=0; i < BIGNUMBER; i++) {
               trafficLight = createImageIcon("trafficlight.gif");
               trafficLightLabel = new JLabel (trafficLight);
               trafficLightPanel.add(trafficLightLabel);
          trafficLightPane.setViewportView(trafficLightPanel);
          trafficLightPane.setPreferredSize(new Dimension(width, height));
          trafficLightPane.setMinimumSize(new Dimension(width, height));
          Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
          width = dimension.width;
          height = 36;
          insets = 4; // Number of pixels to left and/or right of a component
          labelWidth = 40;
          setBounds (0, 0, dimension.width, dimension.height);
          // Set up the problem panel.
          JScrollPane problemPane = new JScrollPane (ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
                    ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
          problemPanel = new JPanel();
          // And a new problem pane, to which the problem panel is added
          problemPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
          problemPane.setViewportView(problemPanel);
          // Set up the JSlitPane
          JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,trafficLightPane,problemPane);
          splitPane.setOneTouchExpandable(true);
          add(splitPane);
      * The screen is divided in two equal sized halves, a left and a right side. Each
      * half is divided into 3 parts. remainingWidth is used to calculate the remaining
      * width inside a half.
     public static JPanel addProblem (String organisation, String problem) {
          JPanel panel = new JPanel (); // JPanel has FlowLayout as default layout
          panel.setPreferredSize(new Dimension (width, height));
          // First half, containing serverId, customer name, and problem title
          // serverId
          JTextArea serverId = new JTextArea ("99999");
          Font usedFont = new Font ("SanSerif", Font.PLAIN, 12);
          serverId.setFont(usedFont);
          serverId.setPreferredSize(new Dimension(labelWidth, height));
          serverId.setBackground(background);
          panel.add(serverId);
          // Organisation name. Gets 1/3 of remaining width
          remainingWidth = (width/2 - (int)serverId.getPreferredSize().getWidth())/3 - insets;
          JTextArea organisationArea = new JTextArea (organisation);
          organisationArea.setPreferredSize(new Dimension (remainingWidth, height));
          organisationArea.setAlignmentX(SwingConstants.LEFT);
          organisationArea.setBackground(background);
          organisationArea.setLineWrap(true);
          organisationArea.setWrapStyleWord(true);
          organisationArea.setEditable(false);
          panel.add(organisationArea);
          // Problem title
          JTextArea problemArea = new JTextArea (problem);
          problemArea.setPreferredSize(new Dimension (remainingWidth*2, height));
          problemArea.setBackground(background);
          problemArea.setLineWrap(true);
          problemArea.setWrapStyleWord(true);
          problemArea.setEditable(false);
          panel.add(problemArea);
          // Second half, containing severity, CSD and Engineer
          // Severity
          JTextArea severity = new JTextArea ("WARN");
          severity.setFont(usedFont);
          severity.setBackground(background);
          severity.setPreferredSize(new Dimension(labelWidth, height));
          panel.add(severity);
          // CSD
          JLabel csdField = new JLabel("CSD:");
          csdField.setFont(usedFont);
          JComboBox csdList = new JComboBox(csdEngineers);
          csdList.setFont(usedFont);
          csdList.setSelectedIndex(6);
          // csdList.addActionListener(this);
          panel.add(csdField);
          panel.add(csdList);
          // Solver, another ComboBox
          JLabel engineerField = new JLabel("Solver:");
          engineerField.setFont(usedFont);
          JComboBox engineerList = new JComboBox(engineers);
          engineerList.setFont(usedFont);
          engineerList.setSelectedIndex(0);
          // engineerList.addActionListener(this);
          panel.add(engineerField);
          panel.add(engineerList);
          // Empty panel to be added after this panel
          JPanel emptyPanel = new JPanel();
          emptyPanel.setPreferredSize(new Dimension (width, 15));
          return panel;
      * ActionListener
      * @param args
     public void actionPerformed(ActionEvent event) {
          System.out.println ("Burp");
     private static ImageIcon createImageIcon(String path) {
          java.net.URL imgURL = JSplitPaneProblem.class.getResource(path);
          if (imgURL != null) {
               return new ImageIcon(imgURL);
          } else {
               System.err.println("Couldn't find file: " + path);
               return null;
     private static void createAndShowGUI() {
          //Create and set up the window.
          JFrame frame = new JFrame("JSlitPaneProblem");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          // Set the size of the window so in covers the whole screen
          Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
          frame.setBounds (0, 0, dimension.width, dimension.height);
          //Create and set up the content pane.
          JComponent newContentPane = new JSplitPaneProblem();
          newContentPane.setOpaque(true); //content panes must be opaque
          frame.setContentPane(newContentPane);
          //Display the window.
          //frame.pack();
          frame.setVisible(true);
          // Add panels
          problemPanel.setPreferredSize(new Dimension(dimension.width, dimension.height - height));
          for (int j=0; j < BIGNUMBER; j++) {
               problemPanel.add(addProblem("Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch Computer Shop",
               "expected string or buffer, but that is not everyting, as this problem description is extremely long. And as I am chatty, I add some more length"));
               JPanel emptyPanel = new JPanel();
               emptyPanel.setPreferredSize(new Dimension (width, 15));
               problemPanel.add(addProblem("My Company", "I have no problem"));
     public static void main(String[] args) {
          //Schedule a job for the event-dispatching thread:
          //creating and showing this application's GUI.
          javax.swing.SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    createAndShowGUI();
}If you want to try it out with the trafficlight.gif mentioned in the code, get it from
http://www.hermod.nl/images/trafficlight.gif
The problem I have with the current code is that in the following line
trafficLightLabel.setPreferredSize(new Dimension (width, height + 15));I try to set the size of the top panel, but the program disregards what I instruct it to do.
When BIGNUMBER = 1, you will see that part of the bottom of the image is not shown.
Can you help me?
Abel
Edited by: Abel on Feb 27, 2008 2:20 PM
Added
static int BIGNUMBER = 1; and where it is used. If you want to play with the program, change BIGNUMBER to for instance 10

Answer 1

Found it. Add
splitPane.resetToPreferredSizes();as last instruction in createAndShowGUI().