The JSplitPane only supports 2 components (by specification).
In some cases it would be useful to have more than 2 components.
Microsofts MFC splitter supports 16x16 components.
It would be nice to have this capability in Swing as well.

  xxxxx@xxxxx   1998-07-08
A possible workaround for the problem is to nest JSplitPanes into each other.
See also 4131528 about this. Here is an example of how this can be done:

import com.sun.java.swing.*;
import java.awt.*;
import java.awt.event.*;

public class NestedSplitPanes extends JFrame
{
        JButton[]       arrB = new JButton[16];
        JSplitPane[]    arrS = new JSplitPane[15];

        public NestedSplitPanes() {
                super("Nested JSplitPanes");

                for (int i=0; i<16; i++) {
                        arrB[i] = new JButton("Button " + (i + 1));
                }
                for (int i=0; i<8; i++) {
                        arrS[i] = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                                                 true, arrB[i*2], arrB[i*2+1]);
                }
                for (int i=8; i<12; i++) {
                        arrS[i] = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                                                 true, arrS[(i-8)*2],
                                                 arrS[(i-8)*2+1]);
                }
                arrS[12] = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                                          true, arrS[8], arrS[9]);
                arrS[13] = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                                          true, arrS[10], arrS[11]);
                arrS[14] = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                                          true, arrS[12], arrS[13]);
                for (int i=0; i<15; i++) {
                        // The following works because the JButtons in the
                        // JSplitPanes have their own Borders.
                        // Borderless components would have to be given a
                        // border before doing this, otherwise the whole thing
                        // looks really ugly and would even be almost unusable
                        // in the Windows L&F (e.g. try JPanels instead of
                        // JButtons.
                        // If you comment out the following line  you can
                        // observe the stacking border problem (4131528).
                        arrS[i].setBorder(null);
                }

                this.getContentPane().add(arrS[14]);

                this.addWindowListener(new WindowAdapter() {
                        public void windowClosing(WindowEvent ev) {
                                System.exit(0);
                        }
                });

                this.pack();
                this.setVisible(true);
        }

        static public void main(String args[]) {
                new NestedSplitPanes();
        }
}

  xxxxx@xxxxx   1998-07-07
This change was requested by SAP, but I would definetely consider it a low priority RFE right now since the API is frozen.
This change would require public API changes and a major architectural overhaul.

scott.violet 1999-03-01
I agree, a component that split multiple components would be very useful. JSplitPane was designed to split only two components though, splitting multiple components would, more than likely, require breaking backward compatability.

I think this would be a very useful feature, too.  Due to
the major changes that this would entail, I think it would
be better to have a new class rather than retrofitting
JSplitPane.