JMenuBar.setMargin(Insets m) has the following syntax.
public void setMargin(Insets m)
In the following code shows how to use JMenuBar.setMargin(Insets m) method.
import java.awt.Insets; import java.awt.event.KeyEvent; // w w w .jav a2 s . c om import javax.swing.ButtonGroup; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JRadioButtonMenuItem; public class Main { public static void main(String args[]) { JFrame f = new JFrame("JRadioButtonMenuItem Sample"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JMenuBar bar = new JMenuBar(); bar.addNotify(); JMenu menu = new JMenu("Options"); menu.setMnemonic(KeyEvent.VK_O); ButtonGroup group = new ButtonGroup(); JRadioButtonMenuItem menuItem = new JRadioButtonMenuItem("A"); group.add(menuItem); menu.add(menuItem); menuItem = new JRadioButtonMenuItem("B"); group.add(menuItem); menu.add(menuItem); menuItem = new JRadioButtonMenuItem("C"); group.add(menuItem); menu.add(menuItem); bar.add(menu); bar.setMargin(new Insets(3,3,3,3)); f.setJMenuBar(bar); f.setSize(300, 200); f.setVisible(true); } }