Таблица не по центру экрана

package interface1;
 
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
 
/**
 *
 * @author user
 */
public class Interface1 {
public static void main(String[] args) {
String[] columnNames = {
     "Name",
     "Last modified",
     
}; 
         
         
         String[][] data = {
     {"addins", "02.11.2006 19:15", "Folder", ""},
     {"AppPatch", "03.10.2006 14:10", "Folder", ""},
     {"assembly", "02.11.2006 14:20", "Folder", ""},
     {"Boot", "13.10.2007 10:46", "Folder", ""},
     {"Branding", "13.10.2007 12:10", "Folder", ""},
     {"Cursors", "23.09.2006 16:34", "Folder", ""},
     {"Debug", "07.12.2006 17:45", "Folder", ""},
     {"Fonts", "03.10.2006 14:08", "Folder", ""},
     {"Help", "08.11.2006 18:23", "Folder", ""},
     {"explorer.exe", "18.10.2006 14:13", "File", "2,93MB"},
     {"helppane.exe", "22.08.2006 11:39", "File", "4,58MB"},
     
}; 
         
         
         
JFrame mainwindow = new JFrame("Пробное окно");
mainwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GridBagConstraints c = new GridBagConstraints();
mainwindow.setLayout(new GridBagLayout());
mainwindow.setLocationRelativeTo(null);
mainwindow.pack();
mainwindow.setVisible(true);
 
 
JPanel mypanel = new JPanel();
 
JTable table = new JTable(data, columnNames);
table.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
 
 
table.addMouseListener(new Newaction());
 
 
JScrollPane scrollPane = new JScrollPane(table);
 
 
c.fill = GridBagConstraints.BOTH;
c.anchor = GridBagConstraints.PAGE_START;
 
 
 
c.weightx = 1;
c.gridwidth=2;
 
c.gridx = 0;
c.gridy = 0;
mainwindow.getContentPane().add(scrollPane,c);
 
JButton buttom= new JButton("Button 2");
c.gridx = 0;
c.gridy = 1;
 c.gridheight = 1;
 c.gridwidth = 1;
 
c.fill=GridBagConstraints.VERTICAL ;
 
JButton buttom1= new JButton("Кнопка выбора 1");
c.gridx = 1;
c.gridy = 1;
c.fill=GridBagConstraints.VERTICAL ;
 c.gridheight = 1;
 c.gridwidth = 1;
 
 
 
mainwindow.getContentPane().add(buttom, c);
mainwindow.getContentPane().add(buttom1 ,c);
 
mainwindow.pack();
 
 
 
 
 
 
 
     
        
    
        }
}

JFrame mainwindow = new JFrame("Пробное окно");
mainwindow.setHorizontalAlignment(SwingConstants.LEFT);
 
mainwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
GridBagConstraints c = new GridBagConstraints();
mainwindow.setLayout(new GridBagLayout());

setVerticalAlignments();

JFrame mainwindow = new JFrame("Пробное окно");
 
 
mainwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
GridBagConstraints c = new GridBagConstraints();
mainwindow.setLayout(new GridBagLayout());
mainwindow.setLocation(0,0);
mainwindow.pack();
mainwindow.setVisible(true);