i want to set a size for frame but i cant, why? the frame is in createandshowgui method i did set for frame,table everything but didnt do anything, i want to set 1024x768
public static class DisplayResult extends JPanel {
public DisplayResult() {
    super(new GridLayout(1,0));
    DefaultTableModel model = new DefaultTableModel(data, columnNames);
    final JTable table = new JTable(model);
    table.setPreferredScrollableViewportSize(new Dimension(500, 70));
    table.setFillsViewportHeight(true);
    table.setPreferredScrollableViewportSize(table.getPreferredSize());
    table.setFillsViewportHeight(true);
    if (DEBUG) {
        table.addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
                printDebugData(table);
            }
        });
    }
    JScrollPane scrollPane = new JScrollPane(table);
    add(scrollPane);
}
public static void createAndShowGUI() {
    final JButton button1=new JButton("Vissza");
    JPanel panel=new JPanel();
    final JFrame frame = new JFrame("Database Data");
    frame.setLayout(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(1024,768);
    DisplayResult newContentPane = new DisplayResult();
    newContentPane.setOpaque(true); //content panes must be opaque
    frame.setContentPane(newContentPane);
    frame.add(panel);
    panel.add(button1);
    frame.pack();
    frame.setVisible(true);
}
 
     
     
    