为什么setLayout(new BorderLayout()),为有这样的问题？

Question

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class E1203 extends JFrame implements ActionListener
{
private Container c;
private JPanel sp,cp;
private JButton[] button1,button2;
public E1203(String title)
{
super(title);
c=getContentPane();
sp=new JPanel(new GridLayout(2,3));
cp=new JPanel(new GridLayout(3,2));
String[] name={"一","二","三","四","五","六"};
button1=new JButton[name.length];
button2=new JButton[name.length];
for(int i=0;i<name.length;i++)
{
button1[i]=new JButton(name[i]);
button1[i].addActionListener(this);
cp.add(button1[i]);
button2[i]=new JButton(name[i]);
button2[i].addActionListener(this);
sp.add(button2[i]);
}
c.add(cp);
setSize(350,200);
show();
}
private boolean b;
public void actionPerformed(ActionEvent e)
{
if(sp.isDisplayable())
{
c.add(cp);
c.remove(sp);
}
else
{
c.add(sp);
c.remove(cp);
}
c.validate();
}
public static void main(String[] args)
{
E1203 app=new E1203("转换格子");
app.addWindowListener(new MyWindowListener());
}
}

Answer 1

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class E1203 extends JFrame implements ActionListener
{
private Container c;
private JPanel sp,cp;
private JButton[] button1,button2;
public E1203(String title)
{
super(title);
c=getContentPane();
sp=new JPanel(new GridLayout(2,3));
cp=new JPanel(new GridLayout(3,2));
String[] name={"一","二","三","四","五","六"};
button1=new JButton[name.length];
button2=new JButton[name.length];
for(int i=0;i<name.length;i++)
{
button1[i]=new JButton(name[i]);
button1[i].addActionListener(this);
cp.add(button1[i]);
button2[i]=new JButton(name[i]);
button2[i].addActionListener(this);
sp.add(button2[i]);
}
c.add(cp);
setSize(350,200);
show();
}
private boolean b;
public void actionPerformed(ActionEvent e)
{
if(sp.isDisplayable())
{
c.add(cp);
c.remove(sp);
}
else
{
c.add(sp);
c.remove(cp);
}
c.validate();
c.repaint();
}
public static void main(String[] args)
{
E1203 app=new E1203("转换格子");
                  app.addWindowListener(new MyWindowListener()); }
}