问题描述

新手求教 请大家帮忙看下源码

------------------------DAL------------------------------------------------------------
public List select(int UserID)
{
//初始化数据库连接对象
DateAccessLaye dbmyfile = new DateAccessLaye();
//初始化myfilemodel对象的集合实例
DataTable dsmf = dbmyfile.GetDataTable(""SELECT TitleFSizeCheckcodeUploadtime FROM myfile WHERE UserID="" + UserID);
List lmfm = new List();
myfilemodel mfmd = new myfilemodel();
foreach (DataRow dr in dsmf.Rows)
{
mfmd.Title = dr[""Title""].ToString();
mfmd.FSize = (float)System.Convert.ToDouble(dr[""FSize""].ToString());
mfmd.Checkcode = dr[""Checkcode""].ToString();
mfmd.Uploadtime = Convert.ToDateTime(dr[""Uploadtime""]);
lmfm.Add(mfmd);
}
return lmfm;
}
---------------------------------------------------------BLL-------------------------
public List select(int UserID)
{
myfiledal mf = new myfiledal();
return mf.select(UserID);
}
-------------------------------UI------------------------------------------------
protected void Button8_Click(object sender EventArgs e)
{
int s = 0;
s = Convert.ToInt32(TextBox1.Text);
//GridView gv = new GridView();
//gv.DataSource = mf.select(s);
GridView1.DataSource = mf.select(s);
GridView1.DataBind();

}    -------------------------DateAccessLaye----------------------------------------     public DateAccessLaye()    {       #region 构造器        //获取连接字符串       constring =ConfigurationManager.ConnectionStrings[""ConnectionString""].ConnectionString;       #endregion    }    public DataTable GetDataTable(string selectCommand){    DataTable dt;    //设置连接对象    _sqlconnection = new SqlConnection(constring);    //设置命令对象    _sqlCmd = new SqlCommand();    _sqlCmd.Connection = _sqlconnection;    _sqlCmd.CommandType = CommandType.Text;    _sqlCmd.CommandText = selectCommand;    //初始化数据适配器    _sqlconnection.Open();    //DataTable DD = new DataTable();    //int a = _sqlCmd.ExecuteNonQuery();    _sqlAdp = new SqlDataAdapter(_sqlCmd);    //初始化DataSet    _sqlconnection.Close();    dt = new DataTable();    //填充DataSet    _sqlAdp.Fill(dt);    return dt;}    ---------------------------------------------------------------------------------    数据在DAL层应该已经是获取了，但是一直对这一句：**GridView1.DataSource = mf.select(s);**    报“未将对象引用设置到对象的实例”的错

解决方案

很多可能性，要调试才知道。

解决方案二：
没人帮忙看一下吗，关于list泛型存储数据在grideview上显示的问题，没办法显示，报“未将对象引用设置到对象的实例”的错