下面程序中addcomponent()函数参数数表中第四个和第五参数怎理解？

下面程序中addcomponent()函数参数数表中第四个和第五参数是指定组件的坐标吧，但在生成的窗口中把相应的组件与那俩个坐标比了一下，很迷惑，感觉组建的位置与那辆个坐标值不一样（别用帮助文档中的解释，我刚才看了一下不好懂（恕我愚钝））   
谢谢package hello;
import java.awt.*;
import javax.swing.*;
public class test extends JFrame
{    JButton bntsz,bntdl;
    JLabel lblzc,lblzh,lbltest;
    JTextField txtzh;
    JPasswordField pwdmm;
    JCheckBox ckbjm,ckbdl;
    JPanel pnlmain;
    GridBagLayout gbl;
    GridBagConstraints gbc;    public test()
    {
        super("QQ 2011");
        pnlmain=new JPanel();
        this.getContentPane().add(pnlmain);
 gbl =new GridBagLayout();
        gbc=new GridBagConstraints();
        pnlmain.setLayout(gbl); 
 bntsz=new JButton("设置");
        bntdl=new JButton("安全登录");
        lbltest=new JLabel("测试");
        lblzc=new JLabel("注册");
        lblzh=new JLabel("找回");
        txtzh=new JTextField(20);
        pwdmm=new JPasswordField(20);
        ckbjm=new JCheckBox("记住密码");
        ckbdl=new JCheckBox("自动登录");
        pnlmain.add(txtzh);
        pnlmain.add(pwdmm);
        pnlmain.add(lblzc);
        pnlmain.add(lblzh);
        pnlmain.add(bntsz);
        gbc.weightx=0;
        gbc.weighty=0;
        gbc.fill=GridBagConstraints.BOTH;
        addcomponent(txtzh,gbl,gbc,0,0,1,3);
        gbc.fill=GridBagConstraints.HORIZONTAL;
        addcomponent(pwdmm,gbl,gbc,0,1,2,1);
        addcomponent(bntsz,gbl,gbc,2,1,2,1);
        gbc.weightx=1000;
        gbc.weighty=1;
        gbc.fill=GridBagConstraints.BOTH;
        addcomponent(bntdl,gbl,gbc,1,1,1,1);
        gbc.weightx=0;
        gbc.weighty=0;
        gbc.fill=GridBagConstraints.BOTH;
        addcomponent(lblzc,gbl,gbc,1,2,1,1);
        addcomponent(lblzh,gbl,gbc,3,0,2,1);
 
        setSize(300,200);
        setVisible(true);
        setResizable(true);
     } //////添加组件的方法
 private void addcomponent(Component c,GridBagLayout g,
             GridBagConstraints gc,int row,int column,int width,int height)
        {
            gc.gridx=column;
            gc.gridy=row;
            gc.gridwidth=width;
            gc.gridheight=height;g.setConstraints(c,gc);
            pnlmain.add(c);
        }
    public static void main(String[] args)
    {
        new test();    }}