Question

您好我正在尝试通过此方法获取总金额

JavaFX

折扣百分比来自控件Swing

如何在下面的代码中实现它，谢谢

calculateDiscount = discount / 100  
Discounted price = Unitprice * calculateDiscount   
total amount = sum(Quantity * Discounted price)

Answer 1

首先计算折扣，然后将其应用于Sum，如下面的代码：

double total = gridpur.Rows.Cast<GridViewRow>()
    .Select(r => Tuple.Create((CheckBox)r.FindControl("chkSel"), (TextBox)r.FindControl("txtQuantity"), (TextBox)r.FindControl("txtUnitprice"), (TextBox)r.FindControl("txtDiscount")))
    .Where(t => t.Item1.Checked)
    .Sum(r => double.Parse(t.Item2.Text) * double.Parse(t.Item3.Text) * double.Parse(t.Item4.Text));

Answer 2

我想你必须使用像

这样的东西

calculateDiscount = discount / 100  
double discounted = Unitprice * calculateDiscount   
total amount = sum(Quantity * discounted)

这里的问题是Discounted price不是变量的有效名称。

double total = gridpur.Rows.Cast<GridViewRow>()
    .Where(r => ((CheckBox)r.FindControl("chkSel")).Checked)
    .Sum(r => double.Parse(((TextBox)r.FindControl("txtQuantity")).Text) *
        double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text));

Answer 3

首先，这段代码真正开始需要ViewModel或其他一些构造，使您能够将业务逻辑与UI分离。

话虽如此，快速而肮脏的答案可以帮助您实现临时linq查询，然后从中构建结果

// From your code
var validRows = gridpur.Rows.Cast<GridViewRow>()
    .Where(r => ((CheckBox)r.FindControl("chkSel")).Checked);
var totals = validRows.Select((r => 
    double.Parse(((TextBox)r.FindControl("txtQuantity")).Text)
    * double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text));

如果我们从linq作为扩展方法转移到linq作为集成查询语法，它也会有所帮助，但随意混合和匹配

var validRows = from r in gridpur.Rows.Cast<GridViewRow>()
    where ((CheckBox)r.FindControl("chkSel")).Checked)
    select r;
var totals = from r in validRows
   select double.Parse(((TextBox)r.FindControl("txtQuantity")).Text)
    * double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text));

我们现在可以在查询中引入let语句和中间变量

var totals = from r in validRows
   let quantity = double.Parse(((TextBox)r.FindControl("txtQuantity")).Text)
   let unitPrice = double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text))
   select quantity * unitPrice;

这样可以使查询更具可读性。

现在我们可以添加其他列和计算

var totals = from r in validRows
   let quantity = double.Parse(((TextBox)r.FindControl("txtQuantity")).Text)
   let unitPrice = double.Parse(((TextBox)r.FindControl("txtUnitprice")).Text))
   let discountPercent = double.Parse(((TextBox)r.FindControl("txtDiscount")).Text) / 100.0d
   select quantity * unitPrice * discountPercent;
 var sumTotals = totals.Sum();

如何在LINQ中计算折扣

3 个答案: