Same size of a JPanel & a JDesktopPane

Question

HI, can someone please tell how to set the same size of JPanel and of JDesktopPane that are in the same JFrame?, I've tried setting the size of the JPanel but when I run it the JPanel is reduced. Here is the code:
import java.awt.*;
import javax.swing.*;
public class Ventana extends JFrame{
    JDesktopPane desktop;
    public Ventana (String title){
        super(title);
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        int maxX = screenSize.width - 400;
        int maxY = screenSize.height - 400;
        setPreferredSize(new Dimension(maxX, maxY));
        JPanel desktopPane = new JPanel();
        desktopPane.setLayout(new BoxLayout(desktopPane, BoxLayout.Y_AXIS));
        JPanel panelBotones = new JPanel();
        panelBotones.setSize(maxX, maxY/2);
        JButton aceptar = new JButton("Aceptar");
        panelBotones.add(aceptar, BorderLayout.PAGE_END);
        desktopPane.add(panelBotones);
        JSeparator sep = new JSeparator();
        desktopPane.add(sep);
        desktop = new JDesktopPane();
        desktop.setSize(maxX, maxY/2);
        JInternalFrame jif = new JInternalFrame("JIF", true, true, true, true);
        jif.setSize(new Dimension(maxX-9, maxY-10));
        desktop.add(jif);
        jif.setVisible(true);
        desktopPane.add(desktop);
        setContentPane(desktopPane);
        desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
        pack();
    public static void createAndShowGUI(){
        try{
             // Set System L&F
             JFrame.setDefaultLookAndFeelDecorated(true);
             JDialog.setDefaultLookAndFeelDecorated(true);
             System.setProperty("sun.awt.noerasebackground", "true");
            //UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        catch (ClassNotFoundException e) {
           // handle exception
        catch (Exception e) {
            try{
                UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
            }catch(Exception f) {
        Ventana miVentana = new Ventana("Ventanita");
        miVentana.setLocationRelativeTo(null);
        miVentana.setVisible(true);
    public static void main(String [] args){
        java.awt.EventQueue.invokeLater(new Runnable(){
            public void run(){
                createAndShowGUI();
}

Answer 1

Never use setSize() when using a layout manager. Use setPreferredSize (and sometimes setMinimumSize and setMaximumSize).
If you want components to be the same size then just use a GridLayout. Of course a GridLayout will just ignore the preferred size and allocate all the space available between the two components.
Edited by: camickr on Jun 27, 2009 11:58 PM