JAVA SE GridBagLayout 有关问题

JAVA SE GridBagLayout 问题
我贴下代码，我想把第二个JPAnel里面的按钮移动到第一个的下方，我用了gridy为什么还是无法移动啊

Java code

import java.awt.*;import javax.swing.*;public class prj1 extends JFrame{    JLabel customerInfo=new JLabel("客户信息");    JLabel customerName=new JLabel("客户名称");    JLabel labelFind=new JLabel("查询");    JLabel customerAddr=new JLabel("客户地址");        JCheckBox find=new JCheckBox();        JComboBox comboCName=new JComboBox();        Container c;    JPanel topPanel=new JPanel();    JPanel bottomPanel=new JPanel();        GridBagLayout gbl=new GridBagLayout();    GridBagLayout gbl2=new GridBagLayout();        GridBagConstraints gbc=new GridBagConstraints();    GridBagConstraints gbc2=new GridBagConstraints();    public prj1()        {        super("维修单收发货程序");        c=this.getContentPane();                topPanel.add(customerInfo);        topPanel.add(customerName);        topPanel.add(labelFind);        bottomPanel.add(customerAddr);        bottomPanel.add(find);                this.setLayout(gbl);                gbc.fill=GridBagConstraints.BOTH;        gbc.anchor=GridBagConstraints.WEST;        gbl.setConstraints(topPanel, gbc);                gbc2.gridy=50;        gbl2.setConstraints(bottomPanel, gbc2);                comboCName.addItem("yangliweng");        comboCName.addItem("kmsfan");        comboCName.addItem("ylw");        topPanel.add(comboCName);                c.add(topPanel);        c.add(bottomPanel);                                this.setSize(400,400);        this.setVisible(true);            }        public static void main(String args[])        {                        prj1 p=new prj1();    }}

------解决方案--------------------------------------------------------
import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Calculator extends JFrame

{
private JTextField displayField;// 计算结果显示区

private String lastCommand;// 保存+,-,*,/,=命令

private double result;// 保存计算结果

private boolean start;// 判断是否为数字的开始



private Container container;
private GridBagLayout layout;
private GridBagConstraints constraints;
public Calculator()
{
super("java_刘阳");
container = getContentPane();
layout = new GridBagLayout();
container.setLayout(layout);
constraints = new GridBagConstraints();

start = true;
result = 0;
lastCommand = "=";
displayField = new JTextField(20);
displayField.setHorizontalAlignment(JTextField.RIGHT);

//注意这里
constraints.gridx =0;
constraints.gridy =0;
constraints.gridwidth = 3; //在第几格显示
constraints.gridheight = 1;
constraints.fill = GridBagConstraints.BOTH;
constraints.weightx = 100; //调整比例
constraints.weighty = 100;
layout.setConstraints(displayField, constraints);
container.add(displayField);



ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();



addButton("Backspace", 0, 1, 2, 1, insert);

addButton("CE", 2, 1, 1, 1, insert);

addButton("C", 3, 1, 1, 1, insert);

addButton("7", 0, 2, 1, 1, insert);

addButton("8", 1, 2, 1, 1, insert);

addButton("9", 2, 2, 1, 1, insert);

addButton("/", 3, 2, 1, 1, command);
//
// addButton("4", 0, 3, 1, 1, insert);
//
// addButton("5", 1, 3, 1, 1, insert);
//
// addButton("6", 2, 3, 1, 1, insert);

// addButton("*", 3, 3, 1, 1, command);
//
// addButton("1", 0, 4, 1, 1, insert);