swing版本计算器排版问题

 1  
 2 package Swing_exercise;
 3 
 4 import java.awt.*;
 5 
 6 import javax.swing.*;
 7 
 8 public class Calc extends JFrame {
 9 
10 JPanel mainPanle, show, rightPanel;
11 
12 JTextField showIn;
13 
14 JButton[] jbs = new JButton[9];
15 JButton zero = new JButton("0");
16 JButton add1 = new JButton("+");
17 JButton less = new JButton("-");
18 JButton muit = new JButton("*");
19 JButton div = new JButton("/");
20 JButton point = new JButton(".");
21 JButton equal = new JButton("=");
22 
23 Calc() {
24 mainPanle = new JPanel(new GridLayout(4, 3, 10, 10));
25 show = new JPanel(new FlowLayout());
26 rightPanel = new JPanel(new GridLayout(4, 1, 10, 10));
27 
28 for (int i = 0; i < 9; i++) {
29 jbs[i] = new JButton(String.valueOf(i + 1));
30 
31 }
32 for (int i = 0; i < 9; i++) {
33 mainPanle.add(jbs[i]);
34 }
35 mainPanle.add(point);
36 mainPanle.add(zero);
37 mainPanle.add(equal);
38 
39 showIn = new JTextField(20);
40 show.add(showIn);
41 
42 add1.setForeground(Color.gray);
43 add1.setBackground(Color.black);
44 add1.setFont(new Font("黑体", Font.BOLD, 8));
45 
46 rightPanel.add(add1);
47 rightPanel.add(less);
48 rightPanel.add(muit);
49 rightPanel.add(div);
50 
51 this.add(show, BorderLayout.NORTH);
52 this.add(mainPanle);
53 this.add(rightPanel, BorderLayout.EAST);
54 
55 this.setResizable(false);
56 this.setVisible(true);
57 this.setBounds(400, 300, 250, 320);
58 this.setDefaultCloseOperation(EXIT_ON_CLOSE);
59 
60 }
61 
62 public static void main(String[] args) {
63 new Calc();
64 
65 }
66 
67 }
怎么在JFrame上对左右两个JPanel的间距进行设置??