Thread: Adding Scrollpane to jPanel

I have trouble with adding scrollpane to jpanel. I can't find what is the problem, when i run the program scrollpane is not showing.

import java.awt.Dimension;
import java.awt.GridLayout;  
import javax.swing.BorderFactory;  
import javax.swing.ButtonGroup;  
import javax.swing.JFrame;  
import javax.swing.JPanel;  
import javax.swing.JRadioButton;  
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
 
class FD  
{  
    private JPanel mainPanel = new JPanel(); 
 
 
    private JRadioButton[] verticalRadioBtns = new JRadioButton[40];  
    private JRadioButton[] horizontalRadioBtns = new JRadioButton[6];  
    private ButtonGroup btngrpVertical = new ButtonGroup();  
    private ButtonGroup btngrpHorizontal = new ButtonGroup();  
 
    public FD()  
    {  
        JPanel panelVertical = new JPanel(new GridLayout(0, 1, 5, 5));  
        for (int i = 0; i < verticalRadioBtns.length; i++)  
        {  
            verticalRadioBtns[i] = new JRadioButton("radioArrayVertical Button " + i);  
            btngrpVertical.add(verticalRadioBtns[i]);  
            panelVertical.add(verticalRadioBtns[i]);  
        }  
 
        JPanel panelHorizontal = new JPanel(new GridLayout(1, 0, 5, 5));  
        for (int i = 0; i < horizontalRadioBtns.length; i++)  
        {  
            horizontalRadioBtns[i] = new JRadioButton("radioArray2 Button " + i);  
            btngrpHorizontal.add(horizontalRadioBtns[i]);  
            panelHorizontal.add(horizontalRadioBtns[i]);  
        }  
 
        panelVertical.setBorder(BorderFactory.createTitledBorder("Vertical Layout"));  
        panelHorizontal.setBorder(BorderFactory.createTitledBorder("Horizontal Layout"));
 
 
        //HERE IS MY PROBLEM !!!!
        JScrollPane scroll = new JScrollPane(panelVertical,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
 
        mainPanel.add(panelVertical);  
        mainPanel.add(panelHorizontal);
 
    }  
 
    public JPanel getMainPanel()  
    {  
        return mainPanel;  
    }  
 
    private static void createAndShowUI()  
    {  
        JFrame frame = new JFrame("Abbas");  
        frame.getContentPane().add(new FD().getMainPanel());  
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
        frame.pack();  
        //frame.setLocationRelativeTo(null);
        //frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
        frame.setVisible(true);
    }  
 
    public static void main(String[] args)  
    {  
        java.awt.EventQueue.invokeLater(new Runnable()  
        {  
            public void run()  
            {  
                createAndShowUI();
 
            }  
        });  
    }  
}

Where do you add the JScrollPane object to any container?

Aren't these codes adding ?

JScrollPane scroll = new JScrollPane(panelVertical,JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
mainPanel.add(panelVertical);

The first statement creates a JScrollPane object.
The second statement adds panelVertical to the mainPanel container?

Where do you add scroll to anything?