c# - 在 DataGridView 中手动添加行

Question

我想测试 DataGridView 中的行颜色变化，所以我编写了该代码：

dataGridView1.Rows.Add(new object[] { "Uno", "No" });
dataGridView1.Rows.Add(new object[] { "Due", "No" });
dataGridView1.Rows.Add(new object[] { "Tre", "Yes" });
dataGridView1.Rows.Add(new object[] { "Quattro", "No" });
dataGridView1.Rows.Add(new object[] { "Cinque", "Yes" });

private void button1_Click(object sender, EventArgs e)
    {            
        foreach (DataGridViewRow row in dataGridView1.Rows)
        {
            if (row.Cells[1].Value.ToString() == "Yes")
                row.DefaultCellStyle.ForeColor = Color.Red;
            else
                row.DefaultCellStyle.ForeColor = Color.Green;
        }
    }

所以，有五行两列。但是当我试图改变颜色时，它给了我一个 NullReference 异常，说 row.Cells[1] 值为空。怎么了？

score 0 · Accepted Answer

通过更改您的颜色，rows您DataGridView可以在DataGridView.CellFormatting 事件中执行此操作，并且您的主要问题是使用String.IsNullOrWhiteSpace 方法。

private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    if (e.ColumnIndex == 1)
    {
        if (string.IsNullOrEmpty(dataGridView1[e.ColumnIndex, e.RowIndex].EditedFormattedValue.ToString()))
        {
            if (dataGridView1[e.ColumnIndex, e.RowIndex].EditedFormattedValue.ToString() == "Yes")
            {
                dataGridView1.Rows[e.RowIndex].DefaultCellStyle.ForeColor = Color.Red;
            }
            else
            {
                dataGridView1.Rows[e.RowIndex].DefaultCellStyle.ForeColor = Color.Green;
            }
        }
        else
            dataGridView1.Rows[e.RowIndex].DefaultCellStyle.ForeColor = Color.Green;
    }
}

score 0 · Accepted Answer

尝试使用 check row.IsNewRow，例如

foreach (DataGridViewRow row in dataGridView1.Rows)
{
    if (row.IsNewRow)
      continue;
    if (row.Cells[1].Value.ToString() == "Yes")
      row.DefaultCellStyle.ForeColor = Color.Red;
    else
      row.DefaultCellStyle.ForeColor = Color.Green;
}

score 0 · Accepted Answer

~~删除 if 中的“toString()”，它正在工作。值正在返回一个字符串；）~~

更新：使用这个。它将对象转换为字符串

 if ((string)row.Cells[1].Value == "Yes")
                row.DefaultCellStyle.ForeColor = Color.Red;
            else
                row.DefaultCellStyle.ForeColor = Color.Green;

score 0 · Accepted Answer

我认为您的方法的问题是，一旦将行连接到网格，您就无法更改行的设计。

但是要实现您想要的，您可以使用 RowPrePaint 事件。

即来自我的一个应用程序：

private void tSEventsDataGridView_RowPrePaint(object sender, DataGridViewRowPrePaintEventArgs e)
{
    if (e.RowIndex >= 0)
    {
        //create new CellStyle
        DataGridViewCellStyle cellStyle = new DataGridViewCellStyle();

        //if we have a value and that value is greater than the MaximumHoursWarning setting
        object cellValue = tSEventsDataGridView[eventTimeDataGridViewTextBoxColumn.Index, e.RowIndex].Value;
        if (cellValue is double
            && (double) cellValue > Timesheets.Properties.Settings.Default.MaximumHoursWarning)
            cellStyle.BackColor = Color.FromArgb(255, 220, 220);  //change the color to light red
        else if (e.RowIndex % 2 == 0)
            cellStyle.BackColor = Color.FromArgb(240, 240, 240);          //else keep the alternating background
        else
            cellStyle.BackColor = Color.White;

        //set the CellStyle for this row.
        tSEventsDataGridView.Rows[e.RowIndex].DefaultCellStyle = cellStyle;
    }
}

c# - 在 DataGridView 中手动添加行

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