System.NullReferenceException datagridview对象引用未设置为对象的实例. [英] System.NullReferenceException datagridview object reference not set to an instance of an object.

问题描述

dataGridView.Rows[e.RowIndex].Cells["ReturnQty"].Value.ToString()

如果当前单元格值为null，则显示NullReferenceException 错误:
我想做

If the current cell value is null it shows the NullReferenceException error:
I want to do

if(!String.IsNullOrEmpty(MainGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value.ToString()))
{

       // do sonmthing
}

推荐答案

尝试类似的方法:

Try something like:

if(MainGridView.Rows.Count >0 && MainGridView.Rows[e.RowIndex].Cells[e.ColumnIndex] != null)
{
   if(!String.IsNullOrEmpty(MainGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value))
   {
       // do sonmthind
   }
}

而不是使用.tostring()
使用Convert.tostring()来处理空值
你可以这样写

Hi,

instead of using .tostring()
use Convert.tostring() as it handles null values
u can write like

if(Convert.Tostring(MainGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value)){       // do sonmthing}

希望对您有帮助.......
:-O

Hope it helps..........
:-O

除了Sandeep的回答外，我还会在if内添加e.RowIndex >= 0 && e.ColumnIndex >= 0.
并且IsNullOrEmpty仅采用string作为参数，但是Cell.Value属性的类型为Object.因此，您不能将其直接传递给IsNullOrEmpty方法.

试试这样的东西:

In addition to Sandeep''s answer, I would add e.RowIndex >= 0 && e.ColumnIndex >= 0 inside if.
And IsNullOrEmpty only takes a string as parameter, but Cell.Value property is of type Object. So you can''t pass it directly to the IsNullOrEmpty method.

Try th something like this:

if (MainGridView.Rows.Count > 0 && e.RowIndex >= 0 && e.ColumnIndex >= 0)
{
   DataGridViewCell cell = MainGridView.Rows[e.RowIndex].Cells[e.ColumnIndex];
   if (cell != null && !String.IsNullOrEmpty(cell.Value as string))
   {
       // do something
   }
}

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