How to solve Object Reference Not Set To An Instance Of An Object

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How to solve Object Reference Not Set To An Instance Of An Object

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#1 by (3 votes)

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I have a serious problem. I have a populated GridView with data from a BD MySql working perfectly.
I also have a button to turn it into a table to be inserted into a PDF using iTextSharp which also works perfectly,

c# winforms datagridview

asked by anonymous 24.05.2017 / 03:09

1 answer

Negation operator returns value that should be discarded Insert function in list

score 3 · Accepted Answer

This exception occurs when you call a method (or, more generally, it references) a null object. In the case of the line where the error occurs, one of the objects ( tabela , dataGridView1 , dataGridView1[n, j] or dataGridView1[n, j].Value ) is null . You should find out which one it is.

It is almost certain that tabela is not, otherwise it would never work, whether there is a date filter or not.

dataGridView , would also have caused problem in the first for if it was null (since it refers to the collection dataGridView1.Rows in it.

Since n and j are restricted to the limits in dataGridView1.Rows.Count and dataGridView1.Columns.Count , respectively, we are not likely to have broken the boundaries of the respective collections. Then it remains for us that the problem must be dataGridView1[n, r].Value , that is, for some value of n and r the result of Value must be null .

There are two ways to resolve this problem. The first is using the coalescence operator ?? , like this:

tabela.AddCell(new Phrase((dataGridView1[n, j].Value ?? "").ToString()));

Alternatively, and somewhat more surely, you can (should) replace references to the φ.ToString() method with calls to the Convert.ToString(φ) method, which does not work when φ is null:

tabela.AddCell(new Phrase(Convert.ToString(dataGridView1[n, j].Value)));