Java SE (Java Platform, Standard Edition)

Hello Everyone,

I am having a strange/odd problem with the J Scroll Pane. I have created a J Scroll Pane and added a Mouse Listener to it.

The program that I have created is a Split Pane where when the user hovers the mouse over the left side of the split pane, the left side will expand. What I want is to have the left side of the Split Pane to expand whenever the mouse is rolled over.

The real problem that I am having is that I added a mouse listener to the Scroll Pane that is embedded on the left side of the Split Pane. However, when the mouse hovers over the "SCROLL BAR", it collapses. Here is a short compilable code from my program (You can compile these three java files and run it yourself to see what the problem is [it is a bit more clearer when you run the mouse over the scroll bar while the split pane is expanded]):

I have tried all sorts of things such as adding a mouse listener to the Panel that is embedded inside the Scroll Pane. Also, I have tried adding a mouse listener to the the J Tree that is embedded inside the Panel which is embedded inside the Scroll Pane. There seems to be a Java Swing concept that I don't understand fully. If someone can let me know what the problem is, I would appreciate it! Thanks!

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeSelectionModel;
import org.jdesktop.swingx.JXTable;

public class GUI
{
    private JFrame frame;
    private JSplitPane splitPane;
    private JTree tree;
    
    public GUI()
    {
        javax.swing.SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createGUI();
            }
        });
    }
    
    public static void main(String[] args)
    {
        new GUI();
    }
    
    public void createGUI()
    {
        frame = new JFrame("Table");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setPreferredSize(new Dimension(1200, 600));
        frame.setResizable(false);
        
        tree = createTree();
        NavigatorPanel drmnav = new NavigatorPanel(tree);
        SplitPane drmgui = new SplitPane(drmnav, setupTable());
        
        splitPane = drmgui.insertIntoSplitPane();

        tree.addMouseListener(drmgui);
        tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
        
        frame.setContentPane(splitPane);
        frame.pack();
        frame.setVisible(true);
    }
    
    // Arbitrary/Random Data
    public JScrollPane setupTable()
    {
        String[] columnNames = {"Name" , "Age" , "#1", "#2", "#3", "#4", "#5"};
        Object[][] data = new Object[1000][7];
        
        JXTable table = new JXTable(data, columnNames);
        table.setFillsViewportHeight(true);
        JScrollPane sp = new JScrollPane(table);
        sp.setSize(1000, 600);
        
        return sp;
    }
    
    public JTree createTree()
    {
        DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("DRM Log");
        createNodes(rootNode);
        JTree jtree = new JTree(rootNode);
        return jtree;
    }
    
    public void createNodes(DefaultMutableTreeNode root)
    {
        DefaultMutableTreeNode section = null;
        DefaultMutableTreeNode lBlock = null;
        DefaultMutableTreeNode qBlock = null;
        
        for(int i=1; i < 40; i++)
        {
            section = new DefaultMutableTreeNode("Item #" + i);
            root.add(section);

            lBlock = new DefaultMutableTreeNode("Sub #1");
            qBlock = new DefaultMutableTreeNode("Sub #2");
            
            section.add(lBlock);
            section.add(qBlock);
        }
    }
}

That is the first class, here is the second and third classes:

import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JComponent;
import javax.swing.JPanel;

public class NavigatorPanel extends JPanel
{   
    public NavigatorPanel(JComponent component)
    {
        GridBagLayout gbl = new GridBagLayout();
        GridBagConstraints constraint = new GridBagConstraints();
        this.setLayout(gbl);
        constraint.gridx = 0;
        constraint.gridy = 0;
        constraint.gridwidth = 1;
        constraint.gridheight = 1;
        constraint.weightx = 1;
        constraint.weighty = 1;
        constraint.ipadx = 0;
        constraint.ipady = 0;
        constraint.fill = GridBagConstraints.BOTH;
        constraint.insets = new Insets(0,0,0,0);
        this.add(component, constraint);
        this.setBackground(Color.BLACK);
    }
    
    public NavigatorPanel()
    {
        this.setBackground(Color.BLACK);
    }
}

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTree;

public class SplitPane implements MouseListener
{
    private JPanel navigatorPanel;
    private JScrollPane dataScrollPane;
    private JScrollPane navigatorScrollPane;
    private JSplitPane splitPane;
    
    public SplitPane(JPanel navigator, JScrollPane data)
    {
        navigatorPanel = navigator;
        dataScrollPane = data;
    }
    
    public JSplitPane insertIntoSplitPane()
    {
        navigatorScrollPane = new JScrollPane(navigatorPanel);
        navigatorScrollPane.addMouseListener(this);
        
        splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, navigatorScrollPane, dataScrollPane);

        splitPane.setOneTouchExpandable(true);
        splitPane.setDividerLocation(38);
        splitPane.setDividerSize(7);
        
        return splitPane;
    }

    @Override
    public void mouseClicked(MouseEvent e) 
    {   
    }

    @Override
    public void mousePressed(MouseEvent e) 
    {  
    }

    @Override
    public void mouseReleased(MouseEvent e) 
    {
    }

    @Override
    public void mouseEntered(MouseEvent e) 
    {
        System.out.println("Entered Scroll Pane");
        splitPane.setDividerLocation(215);
    }

    @Override
    public void mouseExited(MouseEvent e) 
    {
        System.out.println("Exited Scroll Pane");
        splitPane.setDividerLocation(38);
    }
}