奇怪的问题!高分求救:未将对象引用设置到对象的实例
jhsfg 2004-09-16 10:31:43 这是一个用于判断用户是否在线的程序:我在本地上运行正常!把他放到服务器上就出现以下错误。(而且是有时运行正常的),运行了一段时间就出现以下错误:
[NullReferenceException: 未将对象引用设置到对象的实例。]
System.Data.Select.FindClosestCandidateIndex() +196
System.Data.Select.SelectRows() +180
System.Data.DataTable.Select(String filterExpression) +45
SohoProject.OnLineUser.IsUserOnLine(String name)
SohoProject.PageBase.UserOnLine(String userid)
_ASP.BusinessInfoId_aspx.__DataBind__control4(Object sender, EventArgs e) +277
System.Web.UI.Control.OnDataBinding(EventArgs e) +66
System.Web.UI.Control.DataBind() +26
System.Web.UI.Control.DataBind() +86
System.Web.UI.WebControls.DataList.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem) +127
System.Web.UI.WebControls.DataList.CreateControlHierarchy(Boolean useDataSource) +683
System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) +48
System.Web.UI.WebControls.BaseDataList.DataBind() +23
System.Web.UI.Control.DataBind() +86
System.Web.UI.Control.DataBind() +86
SohoProject.BusinessInfoId.loadDailyPicks(Int32 zkid)
SohoProject.BusinessInfoId.Page_Load(Object sender, EventArgs e)
System.Web.UI.Control.OnLoad(EventArgs e) +67
System.Web.UI.Control.LoadRecursive() +35
System.Web.UI.Page.ProcessRequestMain() +731
程序代码是:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections ;
using System.Threading ;
using System.Web;
using System.Diagnostics;
namespace SohoProject
{
public class OnLineUser:System.Web.UI.Page
{
private static DataTable _alluser;
public DataTable alluser
{
get{return _alluser;}
}
public Boolean IsUserOnLine(string name)
{
if(name!=null&&name.CompareTo("")!=0&&name!=""&&_alluser!=null)
{
string strExpr;
strExpr = "name ='" + name + "'";
DataRow[] curUser;
// Use the Select method to find all rows matching the filter.
curUser = _alluser.Select(strExpr);
if (curUser.Length >0 )
{
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}
}