Java Swing JFrame pack

/**
 * @author L a u tturi.com
 * Java Swing Example: java JFrame pack method
 */

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Lautturi {
	public static void main(String[] args) {
		JFrame frame = new JFrame("Java Swing - lautturi");

		JPanel panel = new JPanel();
		JButton button1 = new JButton("button1");
		JButton button2 = new JButton("button2");
		panel.add(button1);
		panel.add(button2);
		frame.add(panel);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(500, 300);
		frame.setLocationRelativeTo(null);

		// sets size for the frame to fit the preferred size and layouts of its subcomponents
		frame.pack();

		frame.setVisible(true);
	}
}