Strange JFrame border

Question

Hi everybody,
This isn't technically a problem, just something weird going on with my JFrame that I don't quite understand. My JFrame has a JLabel added to the north panel, and a JPanel with 3 JButtons in a 3-column GridLayout added to the south panel. When the frame renders, the little gray default border around the JFrame is the same width all the way around, except for on the right side of the button panel, where it's a little wider, so it looks like the JLabel in the top panel is longer than the button panel. It's not really a big deal, but I was just curious, what could cause this to happen? I've never seen anything like this before.
Any explanation would be great, and thanks!
Jezzica85

Answer 1

Ah, yes, the good old self-contained program. I was hoping we wouldn't need one this time, but I guess I should just make a habit of it.
Anyway, here it is:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class Test {
     public static void main(String args[]) {
          try {
               JFrame frame = new JFrame( "Test" );
               frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
               frame.setLayout( new BorderLayout() );
               frame.setSize( 700, 500 );
               // Create main label
               JLabel label = new JLabel( "  Test  " );
               label.setBackground( Color.black );
               label.setForeground( Color.lightGray );
               label.setHorizontalAlignment( SwingConstants.CENTER );
               label.setOpaque( true );
               frame.add( label, BorderLayout.NORTH );
               // Create button panel and buttons
               JPanel panel = new JPanel( new GridLayout( 0, 3 ) );
               for( int i = 0; i < 3; i++ ) {
                    JButton button;
                    if( i == 0 ) {
                         button = new JButton( "I" );
                    } else if( i == 1 ) {
                         button = new JButton( "II" );
                    } else {
                         button = new JButton( "III" );
                    button.setOpaque(true);
                    button.setBackground(Color.pink);
                    panel.add( button );
               frame.add( panel );
               frame.setLocationRelativeTo( null );
               frame.setVisible( true );
          } catch( Exception e ) { e.printStackTrace(); }
}I made the label and buttons colored so you can see the right border more clearly and see what the problem is.
Thanks!
Jezzica85