如何在DataGridView中动态修改指定单元格颜色，现有代码失效如何解决

你写的颜色设置逻辑不生效核心有3个问题：

1. 颜色判断逻辑嵌套在XML节点遍历的循环内，如果对应行ID在XML中没有匹配到<item>节点，所有颜色设置代码都不会执行，而你本身已经直接从行的第7列取到了barhesap的值，不需要依赖XML节点遍历
2. 没有过滤空白新增行、空值行，遇到空值会抛出隐式异常导致逻辑中断
3. 代码执行时机不对，大概率是在DataGridView数据加载完成前就执行了样式设置，后续数据加载覆盖了之前的样式配置

优化后的颜色设置代码 #

private void RefreshCellColor()
{
    // XML加载提到循环外，避免每一行都重复读磁盘
    XDocument x = XDocument.Load(@"../../Data/gemi1/gemi1s1.xml");
    foreach (DataGridViewRow row in dataGridView1.Rows)
    {
        // 跳过新增空白行、空值行
        if (row.IsNewRow || row.Cells[5].Value == null || row.Cells[7].Value == null)
            continue;

        int barhesap = Convert.ToInt32(row.Cells[7].Value);
        int cell5Val = Convert.ToInt32(row.Cells[5].Value);

        // 移除多余的XML节点遍历逻辑，直接判断设置样式
        if (cell5Val <= barhesap / 10)
        {
            row.Cells[5].Style.BackColor = Color.Lime;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 8)
        {
            row.Cells[5].Style.BackColor = Color.Green;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 6)
        {
            row.Cells[5].Style.BackColor = Color.DarkGreen;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 4)
        {
            row.Cells[5].Style.BackColor = Color.Yellow;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 2)
        {
            row.Cells[5].Style.BackColor = Color.Orange;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 1.5)
        {
            row.Cells[5].Style.BackColor = Color.OrangeRed;
            row.Cells[5].Style.ForeColor = Color.Black;
        }
        else if (cell5Val <= barhesap / 1.2)
        {
            row.Cells[5].Style.BackColor = Color.DarkRed;
            row.Cells[5].Style.ForeColor = Color.White;
        }
        else if (cell5Val <= barhesap)
        {
            row.Cells[5].Style.BackColor = Color.Red;
            row.Cells[5].Style.ForeColor = Color.White;
        }
    }
}

正确的调用时机 #

在你数据加载方法yukle()的最后一行调用RefreshCellColor()即可，每次新增、修改数据重新加载列表后都会自动刷新单元格颜色。如果需要每次数据绑定自动触发，可以给DataGridView绑定DataBindingComplete事件：

private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
    RefreshCellColor();
}

内容的提问来源于stack exchange，提问作者Muhammed Sarıgül