List of various line panels in a JPanel

Question

Hi,
I'd like to code a panel which can contain various amounts of other panels which can be considered as "line elements". They consist of a JLable and JTextfield and are all of the same height.
I'd like the main panel at a specified fixed size so I chosed a BoxLayout and Y-Axis and I've put it into a JScrollpane.
Now real fun starts. When I have only two "line panels" in it, they will be streched to fit the size and when it contains more than the Scrollpane's viewport, the JScrollbars show up only if the panel's size is greater than the viewport. What happens if there are more line elements than the main panel can keep, I don't know.
How can I solve this problem having a list of various line elements which keep their size and JScrollbars which show up if necessary? If there might be a better way to do that, please tell me!!!
I wrote this demo-version (2 classes):
The main class with frame and main panel:
package gui;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.WindowConstants;
public class PanOptions extends javax.swing.JPanel{
     private static final long serialVersionUID = 5833715021796955215L;
     private PanLine panLine1;
     private PanLine panLine2;
     private PanLine panLine7;
     private PanLine panLine6;
     private PanLine panLine5;
     private PanLine panLine4;
     private PanLine panLine3;
     private JScrollPane scrollPane;
     private JPanel panel;
     * Auto-generated main method to display this
     * JPanel inside a new JFrame.
     public static void main(String[] args) {
          JFrame frame = new JFrame();
          frame.getContentPane().add(new PanOptions());
          frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
          frame.pack();
          frame.setVisible(true);
      * ctor.
     public PanOptions(){
          initGUI();
     private void initGUI() {
          panel = new JPanel();
          try {
                    this.setPreferredSize(new java.awt.Dimension(623, 140));
               BoxLayout thisLayout = new BoxLayout( panel, javax.swing.BoxLayout.Y_AXIS);
               panel.setLayout(thisLayout);
                    scrollPane = new JScrollPane();
                    this.add(scrollPane);
                    scrollPane.setViewportView( panel);
                         panLine1 = new PanLine();
                         panel.add(panLine1);
                         panLine2 = new PanLine();
                         panel.add(panLine2);
//                    /* if the following part is commented the other two panels will be stretched?!
                         panLine3 = new PanLine();
                         panel.add(panLine3);
                         panLine4 = new PanLine();
                         panel.add(panLine4);
                         panLine5 = new PanLine();
                         panel.add(panLine5);
                         panLine6 = new PanLine();
                         panel.add(panLine6);
                         panLine7 = new PanLine();
                         panel.add(panLine7);
                    scrollPane.setSize(613, 140);
                    scrollPane.setPreferredSize(new java.awt.Dimension(613, 140));
          } catch (Exception e) {
               e.printStackTrace();
}The line element class:
package gui;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class PanLine extends javax.swing.JPanel {
     private static final long serialVersionUID = 4932310577246348201L;
     private JLabel label;
     private JTextField tf;
      * Ctor
     public PanLine() {
          super();
          initGUI();
      * Inits GUI.
     private void initGUI() {
          try {
               GridBagLayout thisLayout = new GridBagLayout();
               thisLayout.rowWeights = new double[] {0.0,0.1};
               thisLayout.rowHeights = new int[] {7,20};
               thisLayout.columnWeights = new double[] {0.0,0.0,0.0,0.0,0.0};
               thisLayout.columnWidths = new int[] {7,370,7,206,7};
               this.setLayout(thisLayout);
               this.setPreferredSize(new java.awt.Dimension(600, 27));
                    label = new JLabel();
                    this.add(label, new GridBagConstraints(1, 1, 1, 1, 0.0, 0.0, GridBagConstraints.CENTER, GridBagConstraints.BOTH, new Insets(0, 0, 0, 0), 0, 0));
                    label.setText( "blablalba");
                    tf = new JTextField();
                    this.add(tf, new GridBagConstraints(3, 1, 1, 1, 0.0, 0.0, GridBagConstraints.CENTER, GridBagConstraints.BOTH, new Insets(0, 0, 0, 0), 0, 0));
                    tf.setText( "blablalba");
          } catch (Exception e) {
               e.printStackTrace();
}

Answer 1

Hi,
I read thru the tuto and tried several things. I still have issues with the BoxLayout. For some strange reason glueing the excess space with Box.createVerticalGlue() doesn't work (at least I couldn't get it to work). So far I fixed the layout setting a maximum size for the line elements.
To tell you the truth I don't really like this solution somehow - why does the glue not work in MY application? It seemed to be so easy in the tutorial and I can remember BoxLayout always having been nice to me?!
This is just the modified main class, the elements are the same.. I'd like to get rid of having to set a max size for the element panels.
package gui;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.WindowConstants;
public class PanOptions01 extends javax.swing.JPanel{
     private static final long serialVersionUID = 5833715021796955215L;
     private PanLine panLine1;
     private PanLine panLine2;
     private PanLine panLine7;
     private PanLine panLine6;
     private PanLine panLine5;
     private PanLine panLine4;
     private PanLine panLine3;
     private JScrollPane scrollPane;
     private JPanel panel;
     * Auto-generated main method to display this
     * JPanel inside a new JFrame.
     public static void main(String[] args) {
          JFrame frame = new JFrame();
          frame.getContentPane().add(new PanOptions01());
          frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
          frame.pack();
          frame.setVisible(true);
      * ctor.
     public PanOptions01(){
          initGUI();
     private void initGUI() {
          panel = new JPanel();
          try {
                    this.setPreferredSize(new java.awt.Dimension(623, 140));
               BoxLayout thisLayout = new BoxLayout( panel, javax.swing.BoxLayout.Y_AXIS);
               panel.setLayout(thisLayout);
                         panLine1 = new PanLine();
                         panel.add(panLine1);
// it's only possible with lines like this:
                         panLine1.setMaximumSize(new java.awt.Dimension(610, 27));
                         panLine2 = new PanLine();
                         panel.add(panLine2);
// it's only possible with lines like this:
                         panLine2.setMaximumSize(new java.awt.Dimension(610, 27));
                    /* if the following part is commented the other two panels will be stretched?!
                         panLine3 = new PanLine();
                         panel.add(panLine3);
                         panLine4 = new PanLine();
                         panel.add(panLine4);
                         panLine5 = new PanLine();
                         panel.add(panLine5);
                         panLine6 = new PanLine();
                         panel.add(panLine6);
                         panLine7 = new PanLine();
                         panel.add(panLine7);
// this has rather no effect - why???
                    panel.add( Box.createVerticalGlue());
                    scrollPane = new JScrollPane();
                    this.add(scrollPane);
                    scrollPane.setSize(613, 140);
                    scrollPane.setPreferredSize(new java.awt.Dimension(613, 140));
                    scrollPane.setViewportView( panel);
                    panel.setPreferredSize(new java.awt.Dimension(610, 150));
          } catch (Exception e) {
               e.printStackTrace();
}