在过滤dataGridView时，对象引用未设置为对象的实例 [英] Object reference not set to an instance of an object, While Filtering dataGridView

问题描述

Hello All，



代码工作正常。但是在过滤dataGridView2时出现错误对象引用没有设置为对象的实例

Hello All,

Code works Fine. But While Filtering dataGridView2 i got an error"Object reference not set to an instance of an object"

private void Form1_Load(object sender, EventArgs e)
       {
           BindGridForExcel();
           BindGridForSql();
       }

       private void BindGridForExcel()
       {
           try
           {
               OleDbConnection theConnection = new OleDbConnection("provider=Microsoft.ACE.OLEDB.12.0;data source=D:\\DotNet\\Copy of Depreciation working Oct-13.xlsx ;Extended Properties=\"Excel 8.0;HDR=NO;IMEX=1;\"");
               theConnection.Open();
               OleDbDataAdapter theDataAdapter = new OleDbDataAdapter("SELECT * FROM [Working$]", theConnection);
               DataSet theDS = new DataSet();
               DataTable dt = new DataTable();
               theDataAdapter.Fill(dt);
               this.dataGridView1.DataSource = dt.DefaultView;
               theConnection.Close();
           }
           catch (Exception ex)
           {

           }

       }

       private void BindGridForSql()
       {
           string connectionString = "Data Source=192.168.0.11;Initial Catalog=30_Nov_13;User ID=sa;Password=super";
           string sql = "SELECT * from [@BA_ODPV] ";

           using (var connection = new SqlConnection(connectionString))
           using (var command = new SqlCommand(sql, connection))
           using (var adapter = new SqlDataAdapter(command))
           {
               connection.Open();
               var dataEntry1 = new DataTable();
               adapter.Fill(dataEntry1);
               dataGridView2.DataSource = dataEntry1;
           }
       }

       private void dataGridView1_DoubleClick(object sender, EventArgs e)
       {
           DataGridViewSelectedRowCollection rc = null;
           rc = dataGridView1.SelectedRows;
           itemcode = rc[0].Cells["F1"].Value.ToString();
           for (int i = 0; i < dataGridView2.Rows.Count; i++)
           {
               if (dataGridView2.Rows[i].Cells[2].Value.ToString() == itemcode)
               {
                   dataGridView2.Rows[i].Selected = true;
                   dataGridView2.Rows[i].Visible = true;
               }
           }
       }

推荐答案

，连接）;
DataSet theDS = new DataSet（）;
DataTable dt = new DataTable（）;
theDataAdapter.Fill（dt）;
this .dataGridView1.DataSource = dt.DefaultView;
theConnection.Close （）;
}
catch （例外情况）
{

}

}

private void BindGridForSql（）
{
string connectionString = 数据源= 192.168 .0.11;初始目录= 30_Nov_13;用户ID = sa;密码=超级;
string sql = SELECT *来自[@BA_ODPV];

使用（ var connection = new SqlConnection（connectionString））
使用（ var command = new SqlCommand（sql，connection））
使用（ var adapter = new SqlDataAdapter（command））
{
connection.Open（）;
var dataEntry1 = new DataTable（）;
adapter.Fill（dataEntry1）;
dataGridView2.DataSource = dataEntry1;
}
}

私有 void dataGridView1_DoubleClick（ object sender，EventArgs e）
{
DataGridViewSelectedRowCollection rc = null ;
rc = dataGridView1.SelectedRows;
itemcode = rc [ 0 ]。单元格[ F1] Value.ToString（）;
for （ int i = 0 ; i < dataGridView2.Rows.Count; i ++）
{
if （dataGridView2.Rows [i] .Cells [ 2 ]。Value.ToString（）== itemcode）
{
dataGridView2.Rows [i] .Selected = true ;
dataGridView2.Rows [i] .Visible = true ;
}
}
}

", theConnection); DataSet theDS = new DataSet(); DataTable dt = new DataTable(); theDataAdapter.Fill(dt); this.dataGridView1.DataSource = dt.DefaultView; theConnection.Close(); } catch (Exception ex) { } } private void BindGridForSql() { string connectionString = "Data Source=192.168.0.11;Initial Catalog=30_Nov_13;User ID=sa;Password=super"; string sql = "SELECT * from [@BA_ODPV] "; using (var connection = new SqlConnection(connectionString)) using (var command = new SqlCommand(sql, connection)) using (var adapter = new SqlDataAdapter(command)) { connection.Open(); var dataEntry1 = new DataTable(); adapter.Fill(dataEntry1); dataGridView2.DataSource = dataEntry1; } } private void dataGridView1_DoubleClick(object sender, EventArgs e) { DataGridViewSelectedRowCollection rc = null; rc = dataGridView1.SelectedRows; itemcode = rc[0].Cells["F1"].Value.ToString(); for (int i = 0; i < dataGridView2.Rows.Count; i++) { if (dataGridView2.Rows[i].Cells[2].Value.ToString() == itemcode) { dataGridView2.Rows[i].Selected = true; dataGridView2.Rows[i].Visible = true; } } }

可能的错误：





每当你试图访问一个对象索引时，请确保该对象不为null ...





尝试添加此行

Possible errors :


whenever u try to access an object index,, please make sure that the object is not null...


try adding this line

 if( dt != null )
 above
this.dataGridView1.DataSource = dt.DefaultView;



try adding this line
if( rc != null && rc.count > )
 if( rc[0].cells.count > 0)
 itemcode = rc[0].Cells["F1"].Value.ToString();


if( dataGridView2 != null && datagridview2.rows.count > 0)
for (int i = 0; i < dataGridView2.Rows.Count; i++)




if( datagridview2.rows[i].cells.count >2 )
if (dataGridView2.Rows[i].Cells[2].Value.ToString() == itemcode)

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