Components getting displayed only when frame size is changed

Question

import java.awt.*;
import javax.swing.*;
public class BorderLayout_another  extends JFrame{
     public BorderLayout_another()
          setLayout(new FlowLayout());
          setSize(500,400);
          setVisible(true);
          add(new JButton("one"));
          add(new JButton("one"));
          add(new JButton("one"));
          add(new JButton("one"));
          add(new JButton("one"));
     public static void main(String[] args)
          new BorderLayout_another();
}If I run the above code then the component in the frame is not visible unless I click restore button of the frame or I resize the frame itself.
Even iconifying and then deiconifying does not solve the problem.
I know I am getting this problem since I have used setVisible(true) before adding the components.
Is there something more to it.

Answer 1

import java.awt.*;
import javax.swing.*;
public class BorderLayout_another  extends JFrame{
     public BorderLayout_another()
          getContentPane().setLayout(new FlowLayout());
          getContentPane().setPreferredSize(500,400);
          getContentPane().add(new JButton("one"));
          getContentPane().add(new JButton("one"));
          getContentPane().add(new JButton("one"));
          getContentPane().add(new JButton("one"));
          getContentPane().add(new JButton("one"));
                pack();
          setVisible(true);
     public static void main(String[] args)
          new BorderLayout_another();
}Later versions of Java will allow you to do without the getContentPane() prefixes but I always use it.