An auto-resizing java panel

gistfile1.java

import java.awt.EventQueue;


public class GridBased extends JFrame {
	private static final long serialVersionUID = -680006681909001923L;

	private JPanel contentPane;
	
	private JButton[][] grid = new JButton[6][5];

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					GridBased frame = new GridBased();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public GridBased() {
		addComponentListener(new ComponentAdapter() {
			@Override
			public void componentResized(ComponentEvent arg0) {
				doSize();
			}
		});
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		contentPane.setLayout(null);
		setContentPane(contentPane);
		
		setupGrid();
	}
	
	
	/**
	 * This method is called only once on the creation of the 
	 * panel.  It goes through all of the cells in the grid and
	 * adds the JButton.
	 */
	private void setupGrid(){
		for(int i=0;i<grid.length;i++){
			for(int k=0;k<grid[i].length;k++){
				grid[i][k] = new JButton("["+i+"]["+k+"]");
				getContentPane().add(grid[i][k]);
			}
		}
		
		doSize();
	}
	
	/**
	 * This method is called once after the creation of the grid, and every
	 * time that the window is resized;
	 */
	private void doSize(){
		for(int i=0;i<grid.length;i++){
			for(int k=0;k<grid[i].length;k++){
				
				int width = contentPane.getWidth()/grid.length;
				int height = contentPane.getHeight()/grid[0].length;
				
				int x = width*i;
				int y = height*k;
				
				grid[i][k].setBounds(x, y, width, height);
			}
		}
	}

}