Question

我尝试使用“下一个/上一个”按钮循环浏览XML记录。我已经编写了代码来获取第一个供应商，但我用来获得第二个供应商和第三个供应商的代码等等都没有用。我已经包含了初始代码来检索数据，我尝试过的循环以及我给出的XML文件。

    List <Vendor> v = VendorDB.GetVendors();

               Vendor vendor1 = v[0];

               txtName.Text = vendor1.Name.ToString();
               txtAddress.Text = vendor1.Address.ToString();
               txtCity.Text = vendor1.City.ToString();
               txtZip.Text = vendor1.Zip.ToString();
               txtPhone.Text = vendor1.Phone.ToString();
               txtSalesYTD.Text = vendor1.YTD.ToString();
               txtSalesRep.Text = vendor1.Contact.ToString();
               txtComments.Text = vendor1.Comment.ToString();

            private void btnNext_Click(object sender, EventArgs e) //try doing if statements for each vendor
        {
            List<Vendor> v = VendorDB.GetVendors();
            for (int i = 0; i < v.Count; i++)
            {

                Vendor vendor1 = v[i];
                txtName.Text = vendor1.Name.ToString();
                txtAddress.Text = vendor1.Address.ToString();
                txtCity.Text = vendor1.City.ToString();
                txtZip.Text = vendor1.Zip.ToString();
                txtPhone.Text = vendor1.Phone.ToString();
                txtSalesYTD.Text = vendor1.YTD.ToString();
                txtSalesRep.Text = vendor1.Contact.ToString();
                txtComments.Text = vendor1.Comment.ToString();
            }
        }

        <?xml version="1.0" encoding="utf-8"?>
<Vendors>
  <Vendor>
    <Name>Scarmado Produce Co.</Name>
    <Address>244 Southwest Dr.</Address>
    <City>Bryan</City>
    <State>Texas</State>
    <ZIP>77805</ZIP>
    <Phone>9797784456</Phone>
    <YTD>2500000</YTD>
    <Comment>Great vendor</Comment>
    <Contact>James Scarmado</Contact>
    <DefaultDiscount>15</DefaultDiscount>
  </Vendor>
  <Vendor>
    <Name>Talbort Restaurant Supplies</Name>
    <Address>2533 Broadway Ave.</Address>
    <City>New Orleans</City>
    <State>LA USA</State>
    <ZIP>89554</ZIP>
    <Phone>7664028762</Phone>
    <YTD>1589000</YTD>
    <Comment></Comment>
    <Contact>Joan Fishing</Contact>
    <DefaultDiscount>20</DefaultDiscount>
  </Vendor>
  <Vendor>
    <Name>Famous Meats</Name>
    <Address>222 Swey Ave.</Address>
    <City>Bangkok</City>
    <State>Thailand</State>
    <ZIP>75110</ZIP>
    <Phone>883778723</Phone>
    <YTD>186000</YTD>
    <Comment>Good vendor</Comment>
    <Contact>Faye Smith</Contact>
    <DefaultDiscount>15</DefaultDiscount>
  </Vendor>
  <Vendor>
    <Name>Duetsch Products</Name>
    <Address>253 Hamburg Ave.</Address>
    <City>Hamburg</City>
    <State>Germany</State>
    <ZIP>APO 76632</ZIP>
    <Phone>109019834</Phone>
    <YTD>258260</YTD>
    <Comment>Difficult delivery system</Comment>
    <Contact>Ian Friberg</Contact>
    <DefaultDiscount>20</DefaultDiscount>
  </Vendor>
  <Vendor>
    <Name>Allegheny Drink Products</Name>
    <Address>2862 Hamilton St.</Address>
    <City>Dallas</City>
    <State>Texas</State>
    <ZIP>80256</ZIP>
    <Phone>7149872957</Phone>
    <YTD>875390</YTD>
    <Comment></Comment>
    <Contact>Cheryl Montana</Contact>
    <DefaultDiscount>15</DefaultDiscount>
  </Vendor>
  <Vendor>
    <Name>Best Cheeses Around</Name>
    <Address>2732 Gouda Ct.</Address>
    <City>Lincoln</City>
    <State>Nebraska USA</State>
    <ZIP>67499</ZIP>
    <Phone>4028776509</Phone>
    <YTD>679270</YTD>
    <Comment></Comment>
    <Contact>Dave Pfister</Contact>
    <DefaultDiscount>15</DefaultDiscount>
  </Vendor>
</Vendors>

Answer 1

尝试存储当前供应商的供应商列表和索引以在全局变量中显示。然后要显示给next / prev供应商，只需增加/减少当前供应商索引并刷新UI：

//Declare these as global variable :
List<Vendor> vendors;
int currentVendorIndex = 0;

//populate vendors once (f.e in constructor)
vendors = VendorDB.GetVendors();

private void btnNext_Click(object sender, EventArgs e)
{
    currentVendorIndex++;
    //if index exceeds maximum available index, reset to 0
    if(currentVendorIndex == vendors.Count) currentVendorIndex = 0;

    Vendor vendor1 = vendors[currentVendorIndex];
    txtName.Text = vendor1.Name.ToString();
    txtAddress.Text = vendor1.Address.ToString();
    txtCity.Text = vendor1.City.ToString();
    txtZip.Text = vendor1.Zip.ToString();
    txtPhone.Text = vendor1.Phone.ToString();
    txtSalesYTD.Text = vendor1.YTD.ToString();
    txtSalesRep.Text = vendor1.Contact.ToString();
    txtComments.Text = vendor1.Comment.ToString();
}

更新：

对于上一个按钮，您可以使用与更新相同的逻辑，除了增量部分需要用减量替换：

currentVendorIndex--;
//if index decremented below minimum, reset to maximum index
if(currentVendorIndex < 0) currentVendorIndex = vendors.Count-1;

使用C＃中的下一个/上一个按钮显示XML记录

1 个答案: