datagridview cell click event

Question

I have an event for a cell click in a datagrid view to display the data in the clicked cell in a message box. I have it set to where it only works for a certain column and only if there is data in the cell

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
    if (dataGridView1.CurrentCell.ColumnIndex.Equals(3))
        if (dataGridView1.CurrentCell != null && dataGridView1.CurrentCell.Value != null)
            MessageBox.Show(dataGridView1.CurrentCell.Value.ToString());
}

however, whenever i click any of the column headers, a blank messagebox shows up. I cant figure out why, any tips?

Solution 1

You will also need to check the cell clicked is not the column header cell. Like this:

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
    if (dataGridView1.CurrentCell.ColumnIndex.Equals(3) && e.RowIndex != -1){
        if (dataGridView1.CurrentCell != null && dataGridView1.CurrentCell.Value != null)
            MessageBox.Show(dataGridView1.CurrentCell.Value.ToString());   
}

Solution 2

Check that CurrentCell.RowIndex isn't the header row index.

Solution 3

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{    
    if (e.RowIndex == -1) return; //check if row index is not selected
        if (dataGridView1.CurrentCell.ColumnIndex.Equals(3))
            if (dataGridView1.CurrentCell != null && dataGridView1.CurrentCell.Value != null)
                MessageBox.Show(dataGridView1.CurrentCell.Value.ToString());
}

Solution 4

The accepted solution throws an "object not set to an instance of an object" exception as null reference checking MUST happen before checking the actual value of a variable.

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{    
    if (dataGridView1.CurrentCell == null ||
        dataGridView1.CurrentCell.Value == null ||
        e.RowIndex == -1) return;
    if (dataGridView1.CurrentCell.ColumnIndex.Equals(3))
        MessageBox.Show(dataGridView1.CurrentCell.Value.ToString());
}

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Comments

[MatanKri]

Just notice that you should check ` dataGridView1.CurrentCell != null ` before the first condition ...