[英]Showing Exception - Object reference not set to an instance of an object
在這行代碼dr = dt.Rows[k];
我得到異常Object reference not set to an instance of an object.
我哪里錯了?
public partial class EditEngClgList : Form
{
public EditEngClgList()
{
InitializeComponent();
try
{
acccon = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db1.mdb");
acccon.Open();
}
catch (Exception err)
{
MessageBox.Show("Error:" + err);
}
string sql = "Select * From EngColeges order by EngClgID";
da = new OleDbDataAdapter(sql, acccon);
cmdb = new OleDbCommandBuilder(da);
dt1 = new DataTable();
da.Fill(dt1);
bs = new BindingSource();
bs.DataSource = dt1;
dataGridView1.DataSource = bs;
dataGridView1.Columns[1].Visible = false;
}
private void button4_Click(object sender, EventArgs e)
{
List<int> checkedclg = new List<int>();
DataRow dr;
List<int> checkedclgid = new List<int>();
for (int i = 0; i <= dataGridView1.RowCount - 1; i++)
{
if (Convert.ToBoolean(dataGridView1.Rows[i].Cells["Delete"].Value) == true)
{
checkedclg.Add(i);
checkedclgid.Add(Convert.ToInt16(dataGridView1.Rows[i].Cells["Delete"].Value));
}
}
foreach (int k in checkedclg)
{
dr = dt.Rows[k]; //this datatable object I hae created in another function
dt.Rows[k].Delete();
foreach (int j in checkedclgid)
{
OleDbCommand oleDbCommand = new OleDbCommand("DELETE FROM EngColeges WHERE EngClgID = @clgID", acccon);
oleDbCommand.Parameters.Add("@clgID", OleDbType.Integer).Value = j;
oleDbCommand.Prepare();
oleDbCommand.ExecuteNonQuery();
}
}
}
謝謝你的幫助
在該行上放置一個斷點 - 很可能是dt
對象為null。
為了解決k可能大於Rows.Count的注釋,我認為如果問題是k
,你會得到一個異常,表明索引超出范圍( IndexOutOfBoundsException
)。
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