How to show different JTable without flickering JFrame?

Question

I write a simple application with 2 different tables. if user clicks "1" button, the frame will display table 1. else frame display table2. at the moment the code is like:
     JPanel panel1 = new JPanel();     
     ......//make the panel1 contains 2 buttons
     JPanel panel2 = new JPanel();
      ......//make the panel2 contains one table
     JFrame frame = new JFrame();     
     frame.getContentPane().add(panel1,BorderLayout.NORTH);
     frame.getContentPane().add(panel2,BorderLayout.CENTER);
     frame.setSize(700,500); frame.setLocatio(50,25);
     frame.setVisible(true);in ActionPerformed() method, the code is like:
      if (e.getActionCommand().equals("1")) {
          panel2 = new JPanel();
           ......//make the panel contains table1    
          frame.setVisible(false);
          frame.getContentPane().add(panel2, BorderLayout.CENTER);
          frame.setSize(700,500); frame.setLocatio(50,25);
          frame.setVisible(true);
       } else {  
           ...//do same thing with table2
       }there are 2 problems:
1. every time the frame will flush once if user clicks one button. how to make the frame only change the panel which contains new table but not the button panel?
2. about size: the user may resize the frame by draging one border of the frame. but the new frame always gets a fixed size. how to make the frame get the size the user adjusted?
Maybe solve the first problem can automatically finish the second problem. but I don't know how to do.
Thanks for any help.

Answer 1

I post the same question twice yesterday but receive no answer. I think it should be straight-forward if you know. Is it really that difficult? I need help!
Thanks.