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I want to display a vertical list of JCheckBox-es in a JPanel. But I have decided to wrap each JCheckBox with a JPanel, (thinking that i would need it in future). and i am going to stack these JPanels(containing one JCheckBox each) vertically in another JPanel using BoxLayout.

The BoxLayout is working as expected without any vertical space in between the JPanels added to them. My problem is with these inner JPanels containing individual checkbox. there is a considerable amount of space around the checkbox for each panel. I want to wrap these checkboxes tightly, so that the size of jcheckbox and that of the corresponding jpanel containing them are equal.

for these individual jpanel i have tried layouts - flowlayout and default layout. both didnt help.

How can i fix this? i just simply set the flowlayout and add the jcheckbox directly to the jpanel. no other code i have used.

I am adding an example code: import java.awt.Color; import java.awt.Dimension; import java.awt.FlowLayout;

import javax.swing.BoxLayout;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;

public class TryBox  implements Runnable{

/**
 * @param args
 */
public static void main(String args[])
{
   SwingUtilities.invokeLater(new TryBox());
}
public void run()
{
    class InnerPanel extends JPanel
    {

        public InnerPanel(int i) {
            // TODO Auto-generated constructor stub
            setLayout(new FlowLayout());    

            setBackground(new Color(i*50, i*50, i*50));

            add(new JCheckBox("CheckBox "+i));

        }

    }
    JPanel outerPanel = new JPanel();
    outerPanel.setLayout(new BoxLayout(outerPanel, BoxLayout.Y_AXIS));

    for(int i=0;i<5;i++)
    {
        outerPanel.add(new InnerPanel(i));
    }
     JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JScrollPane sp = new JScrollPane(outerPanel);
        frame.setPreferredSize(new Dimension(200, 600));
        frame.getContentPane().add(new JScrollPane(outerPanel));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
}

}

here frame.setPreferredSize(new Dimension(200, 600)); is making the difference. i want the jpanels to reduce to the size of jcheckboxes. i dont want the jcheckboxes to fit into jpanel's size. if any extra vertical space is there in the container i want it to be left free.

Mohamed Iqzas
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    Look at [this post](http://stackoverflow.com/questions/17951886/cannot-add-checkbox-to-the-jlist/17952530#17952530) for one way to do a list of checkboxes. – splungebob Oct 09 '13 at 13:31
  • thats a nice implementation. i have gone sometime into my approach, and i find it difficult(am lazy) to change it :(. Next time when i would need a list of checkboxes , i am going to use yours. Thanks for the wonderful solution. – Mohamed Iqzas Oct 10 '13 at 07:56

2 Answers2

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The default layout of JPanel is FlowLayout, and the default constructor creates "a default 5-unit horizontal and vertical gap." You can specify no gap:

JPanel panel = new JPanel(new FlowLayout(FlowLayout.CENTER, 0, 0));

In addition, the JCheckBox UI delegate adds Insets that vary by L&F. I would be wary of changing these: the size is negligible and typically required to accommodate selection indication.

trashgod
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1

Did you try setting the margin and border insets to 0 (on the Swing components)?

Harsha R
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