JPanels and SplitPanes difficulty

Question

Hi there, I am playing around with swing at the moment, and am having some difficulty with JPanels and split panes.
What I would like to get eventually is a JFrame split up like this:
|             |            |
|             | -----------|
|             |            |
|             |            | 
|             |            |
|             | -----------|
----------------------------Just in case that v poor diagram does not suffice - The JFrame should be split roughly in half with a vertical line, then the right hand panel should be split into thirds (roughly) with two horizontal lines.
The code that I have is this:
import javax.swing.JFrame;
import java.awt.*;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSplitPane;
     public class ccssc  {
          private JPanel jsp2;
          private JPanel jsp1;
          private JPanel jsp3;
          private JPanel jsp4;
          private JLabel jl = new JLabel("HELLO JLABEL");
          public ccssc(){
               JFrame.setDefaultLookAndFeelDecorated(true);
          JFrame frame = new JFrame("Self Contained Example");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setPreferredSize(new Dimension(1200, 900));
          //init
          jsp2 = new JPanel();
          jsp1 = new JPanel();
          jsp3 = new JPanel();
          jsp4 = new JPanel();
          jsp3.setSize(350, 50);
          jsp4.setSize(350, 50);
          jsp1.setSize(900, 1000);
          jsp3.add(jl); //Frame with the JLabel on it.
          jsp1.setBackground(Color.BLUE);
          jsp2.setBackground(Color.BLACK);
          jsp3.setBackground(Color.RED);
          jsp4.setBackground(Color.GREEN);
          JSplitPane splitPane2 = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                 true, jsp3, jsp2);
          JSplitPane splitPane3 = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                 true, splitPane2, jsp4 );
          JSplitPane splitPane1 = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                 true, jsp1, splitPane2);
         splitPane2.setDividerLocation(50);
         splitPane3.setDividerLocation(700);
         splitPane1.setDividerLocation(850);
         frame.add(splitPane3);
         frame.add(splitPane1);
         frame.setResizable(true);
         frame.pack();
          frame.setVisible(true);
          public static void main(String[] args) throws Exception{
               new ccssc();
     }My thinking is that the JSplitPane3 should have as its top half JSplitPane2, and as its bottom half, the new JPanel (jsp4) however, this does not work, it runs fine, but only displays the first 3 JPanels, and only the JSplitPanes 1 and 2.
I am confused, is there something I am missing here?
Thanks for your time,
beccy

Answer 1

Two issues with your code:
You know that you are adding components to JFrame twice without specifying where. When doing this, you are actually adding components to the JFrame's contentPane, and the default layout for the contentPane is a BorderLayout. Thus when you add two things without specifying a location, both are added to the BorderLayout.CENTER position, and thus the second component will completely obscure the first one added.
The other issue is that the API for the JSplitPane.setDividerLocation( ) method states that it only will have an effect after the split pane is correctly realized and on the screen. This will only occur after setVisible(true) has been called. You may want to move these method calls to after the frame has been set visible. If done correctly, you won't have to call setSize on the JPanels (somethiing that shouldn't be done anyways). Something like so:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSplitPane;
import javax.swing.SwingUtilities;
class MyCcssc2 extends JPanel
    public static final Dimension PANEL_SIZE = new Dimension(800, 650);
    private static final long serialVersionUID = 1L;
    private JPanel leftPanel = new JPanel();
    private JPanel rightTopPanel = new JPanel();
    private JPanel rightMidPanel = new JPanel();
    private JPanel rightBottomPanel = new JPanel();
    private JSplitPane rightBottomSP = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
            rightMidPanel, rightBottomPanel);
    private JSplitPane rightSP = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
            rightTopPanel, rightBottomSP);
    private JSplitPane mainSP = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
            leftPanel, rightSP);
    MyCcssc2()
        setLayout(new BorderLayout());
        setPreferredSize(PANEL_SIZE);
        leftPanel.setBackground(Color.blue);
        rightTopPanel.setBackground(Color.red);
        rightMidPanel.setBackground(Color.black);
        rightBottomPanel.setBackground(Color.green);
        add(mainSP);
    public void setDividerLocation()
        mainSP.setDividerLocation(0.5);
        rightSP.setDividerLocation(0.3333);
        rightBottomSP.setDividerLocation(0.3333);
    private static void createAndShowGUI()
        JFrame frame = new JFrame("Swing Application");
        MyCcssc2 ccssc2 = new MyCcssc2();
        frame.getContentPane().add(ccssc2);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        ccssc2.setDividerLocation();
    public static void main(String[] args)
        SwingUtilities.invokeLater(new Runnable()
            public void run()
                createAndShowGUI();
}Also, try to use variable names that are more meaningful. It will make your code that much easier for us to read. Good luck!
Edited by: Encephalopathic on Dec 26, 2007 7:42 AM