all individual panels are not shown inside root panel

Question

I want to add multiple jpanels to jpanel.So i added a root panel to jscrollpane.and then added all individual jpanels to this root panel.I made jscrollpane's scrolling policy as needed.i.e HORIZONTAL_SCROLLBAR_AS_NEEDED,VERTICAL_SCROLLBAR_AS_NEEDED. But the problem is all individual panels are not shown inside root panel.

Code:

JScrollPane scPanel=new JScrollPane();

JPanel rootPanel=new JPanel();
rootPanel.setLayout(new FlowLayout());

JPanel indPanel = new JPanel();
rootPanel.add(indPanel);

JPanel indPanel2 = new JPanel();
rootPanel.add(indPanel2);

//.....like this added indPanals to rootPanel.
scPanel.setViewPortView(rootPanel);
//scPanel.setHorizontalScrollPolicy(HORIZONTAL_SCROLLBAR_AS_NEEDED);

And one more thing is, as i scroll the scrollbar the panels are going out of jscrollpane area. I am not able to see all individual panels, Please suggest me.

Edit: code snippet from double post:

MosaicFilesStatusBean mosaicFilesStatusBean = new MosaicFilesStatusBean();
DefaultTableModel tableModel = null;
tableModel = mosaicFilesStatusBean.getFilesStatusBetweenDates(startDate, endDate);
if (tableModel != null) {
    rootPanel.removeAll();        
    rootPanel.setLayout(new BoxLayout(rootPanel, BoxLayout.PAGE_AXIS));      
    for (int tempRow = 0; tempRow < tableModel.getRowCount(); tempRow++) {

        int fileIdTemp = Integer.parseInt(tableModel.getValueAt(tempRow, 0).toString());
        String dateFromTemp = tableModel.getValueAt(tempRow, 3).toString();
        String dateToTemp = tableModel.getValueAt(tempRow, 4).toString();
        int processIdTemp = Integer.parseInt(tableModel.getValueAt(tempRow, 5).toString());
        int statusIdTemp = Integer.parseInt(tableModel.getValueAt(tempRow, 6).toString());
        String operatingDateTemp = tableModel.getValueAt(tempRow, 7).toString();                
        MosaicPanel tempPanel =           
           new MosaicPanel(fileIdTemp, dateFromTemp, dateToTemp, processIdTemp, statusIdTemp, operatingDateTemp);             
        rootPanel.add(tempPanel);             
    }
    rootPanel.revalidate();
}

Answer 1

The main reason, why you couldn't see your JPanel is that you are using FlowLayout as the LayoutManager for the rootPanel. And since your JPanel added to this rootPanel has nothing inside it, hence it will take it's size as 0, 0, for width and height respectively. Though using GridLayout such situation shouldn't come. Have a look at this code example attached :

import java.awt.*;
import javax.swing.*;

public class PanelAddition
{
    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("Panel Addition Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new GridLayout(0, 1));        
        JScrollPane scroller = new JScrollPane();

        CustomPanel panel = new CustomPanel(1);
        contentPane.add(panel);
        scroller.setViewportView(contentPane);
        frame.getContentPane().add(scroller, BorderLayout.CENTER);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        for (int i = 2; i < 20; i++)
        {
            CustomPanel pane = new CustomPanel(i);
            contentPane.add(pane);
            contentPane.revalidate();
            contentPane.repaint();
        }
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new PanelAddition().createAndDisplayGUI();
            }
        });
    }
}

class CustomPanel extends JPanel
{

    public CustomPanel(int num)
    {
        JLabel label = new JLabel("" + num);
        add(label);
    }

    @Override
    public Dimension getPreferredSize()
    {
        return (new Dimension(200, 50));
    }
}