jtable 不显示的有关问题，多谢（jtable中显示sql中查询的结果集）

jtable 不显示的问题，谢谢（jtable中显示sql中查询的结果集）
import   java.sql.*;
import   javax.swing.table.*;
import   java.util.*;
import   java.awt.*;
import   javax.swing.*;
import   java.awt.event.*;
class   Demo   extends   JFrame   implements   ActionListener
{
JPanel   jp1,jp2;
DefaultTableModel   dtm=null;
JTable   jtb;
JScrollPane   jsp=null;
Vector   row=null;
Vector   col=null;
JButton   jb=null;
//java.sql.ResultSet   rs;
public   Demo()
{
  jp1=new   JPanel();
  jp2=new   JPanel();
  jb=new   JButton( "ok ");
  jb.addActionListener(this);
  dtm=new   DefaultTableModel();
  jtb=new   JTable(dtm);
  jtb.setPreferredScrollableViewportSize(new   Dimension(400,300));
  jsp=new   JScrollPane(jtb);
  jp1.add(jb);
  jp2.add(jsp);
  this.add(jp1, "North ");
  this.add(jp2, "Center ");
  this.pack();
  this.show();    
}

public   void   actionPerformed(ActionEvent   e)
{
if(e.getSource()==jb)
{
try  
{
    Class.forName( "com.microsoft.jdbc.sqlserver.SQLServerDriver ");
    java.sql.Connection   conn   =   java.sql.DriverManager.getConnection( "jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=Northwind ", "sa ", " ");
    java.sql.Statement   stmt   =   conn.createStatement();
    ResultSetrs   =   stmt.executeQuery( "select   *   from   Customers ");
    ResultSetMetaData   rsmd=rs.getMetaData();
    for   (int   i   =   1;   i <=rsmd.getColumnCount();   i++)
    {
    System.out.println   (rsmd.getColumnName(i));//这句话能打印出第第一列的列名   "CustomerID "     说明     连接数据库没有问题啊
    col.add(rsmd.getColumnName(i));///ljlajflajflafja
    }
    while(rs.next())
    {
    Vector   v=new   Vector();
    for   (int   i   =   1;   i <=rsmd.getColumnCount();   i++)
    {
    v.add(rs.getString(i));
    }
    row.add(v);
    }
    dtm.setDataVector(row,col);    
   
        }
        catch   (Exception   ex)  
        {
        System.out.println   (ex.getMessage()+ "error ");
        }
}
}


public   static   void   main(String[]   args)
        {
            new   Demo();
        }
}


[解决办法]
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[解决办法]

光是这些代码的话可能问题出在这里。

Vector row=null;
Vector col=null;

后面也没见你初始化。

一开始就初始化试试看
Vector row=new Vector();
Vector col= new Vector();
[解决办法]
package org.chenliang.interview;

import java.util.Vector;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
public class TableTest {
public static void main(String[] args) {
JFrame Frame = new JFrame( "Frame ");

DefaultTableModel dtm = new DefaultTableModel();

Vector <String> colData = new Vector <String> ();
colData.addElement( "1 ");
colData.addElement( "2 ");
colData.addElement( "3 ");
colData.addElement( "4 ");

Vector <Vector> rowData = new Vector <Vector> ();
for (int i = 0; i < 38; i++) {
Vector <String> v = new Vector <String> ();
for (int j = 0; j < colData.size(); j++) {
v.add( " " + j);
}

rowData.add(v);
}

dtm.setDataVector(rowData, colData);

JTable table = new JTable(dtm);

Frame.add(new JScrollPane(table));
Frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Frame.setSize(200, 200);
Frame.setVisible(true);
}
}