想做成图二的效果但是做成了图一的效果，可以怎样挽救一下吗

package chap;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.LayoutManager;

import javax.swing.*;

public class test8 extends JFrame {

    public test8() {
        JPanel northPanel = new JPanel();
        JPanel southPanel = new JPanel();
        JPanel westPanel = new JPanel();
        JPanel eastPanel = new JPanel();
        JPanel centerPanel = new JPanel();
        JButton button1=new JButton("北方参战者");
        JButton button2=new JButton("西方观察团");
        JButton button3=new JButton("东方观察团");
        JButton button4=new JButton("南方参与者");
        northPanel.add(button1,BorderLayout.NORTH);
        southPanel.add(button2,BorderLayout.WEST);
        westPanel.add(button3,BorderLayout.EAST);
        eastPanel.add(button4,BorderLayout.SOUTH);
        centerPanel.setLayout(new GridLayout(12, 12));

        for (int i = 0; i < 144; i++) {
            JPanel tempPanel = new JPanel();
            if ((i / 12) % 2 == 0) {
                if (i % 2 == 0) {
                    tempPanel.setBackground(Color.WHITE);
                } else {
                    tempPanel.setBackground(Color.BLACK);
                }
            } else {
                if (i % 2 == 0) {
                    tempPanel.setBackground(Color.BLACK);
                } else {
                    tempPanel.setBackground(Color.WHITE);
                }
            }
            centerPanel.add(tempPanel);
        }
        getContentPane().add(northPanel, "North");
        getContentPane().add(southPanel, "South");
        getContentPane().add(westPanel, "West");
        getContentPane().add(eastPanel, "East");
        getContentPane().add(centerPanel, "Center");

        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    public static void main(String[] args) {
        new test8();
    }
}

除了中间的设置面板，四周的不要使用面板，直接把按钮添加过去就可以。
代码如下

public class test8 extends JFrame {
 
    public test8() {
//        JPanel northPanel = new JPanel();
//        JPanel southPanel = new JPanel();
//        JPanel westPanel = new JPanel();
//        JPanel eastPanel = new JPanel();
        JPanel centerPanel = new JPanel();
        JButton button1=new JButton("北方参战者");
        JButton button2=new JButton("西方观察团");
        JButton button3=new JButton("东方观察团");
        JButton button4=new JButton("南方参与者");
        getContentPane().add(button1,BorderLayout.NORTH);
        getContentPane().add(button2,BorderLayout.WEST);
        getContentPane().add(button3,BorderLayout.EAST);
        getContentPane().add(button4,BorderLayout.SOUTH);
        centerPanel.setLayout(new GridLayout(12, 12));
 
        for (int i = 0; i < 144; i++) {
            JPanel tempPanel = new JPanel();
            if ((i / 12) % 2 == 0) {
                if (i % 2 == 0) {
                    tempPanel.setBackground(Color.WHITE);
                } else {
                    tempPanel.setBackground(Color.BLACK);
                }
            } else {
                if (i % 2 == 0) {
                    tempPanel.setBackground(Color.BLACK);
                } else {
                    tempPanel.setBackground(Color.WHITE);
                }
            }
            centerPanel.add(tempPanel);
        }
//        getContentPane().add(northPanel, "North");
//        getContentPane().add(southPanel, "South");
//        getContentPane().add(westPanel, "West");
//        getContentPane().add(eastPanel, "East");
        getContentPane().add(centerPanel, "Center");
 
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    public static void main(String[] args) {
        new test8();
    }
}