客户发票表单；通用列表；C#

Question

我正在做这个项目，有人要求我写一个代码来连接从InvoiceDB和CustomerDB到Form1.Cs的数据。我已经完成了我的代码，但不知何故它不能工作。当我运行一个程序时，form1中的列表视图无法从类中获取数据。我想向专家寻求一些帮助。谢谢。

我的代码Form1.cs

    private void Form1_Load(object sender, EventArgs e)
    {
        {
            **//Get data from Invoice and Customer Class**
            List<Invoice> invoiceList = InvoiceDB.GetInvoices();
            List<Customer> customerList = CustomerDB.GetCustomers();

            **//Query expression**
            var invoices = from invoice in invoiceList
                               join customer in customerList
                               on invoice.CustomerID equals customer.CustomerID
                                orderby customer.Name, invoice.InvoiceTotal descending
                           select new {customer.Name, invoice.InvoiceID, invoice.InvoiceDate, invoice.InvoiceTotal};

            **//Executes the query**
           string customerName = " ";
            int i = 0;
            foreach (var invoice in invoices)
            {
                if (invoice.Name != customerName)
                {
                    lvInvoice.Items.Add(invoice.Name);
                    customerName = invoice.Name;
                }
                else
                {
                    lvInvoice.Items.Add(" ");
                }
                lvInvoice.Items[i].SubItems.Add(invoice.InvoiceID.ToString());
                lvInvoice.Items[i].SubItems.Add(Convert.ToDateTime(invoice.InvoiceDate).ToShortDateString());
                lvInvoice.Items[i].SubItems.Add(invoice.InvoiceTotal.ToString("C"));
                i += 1;
            }
    }
    }

CustomerDB类

public static class CustomerDB
{

    private const string Dir = @""; 
    private const string Path = Dir + "CustomersX23.txt";

    public static List<Customer> GetCustomers()
    {
        List<Customer> customers = new List<Customer>();

        StreamReader textIn = new StreamReader(
            new FileStream(Path, FileMode.Open, FileAccess.Read));

        while (textIn.Peek() != -1)
        {
            string row = textIn.ReadLine();
            string[] columns = row.Split('|');
            Customer customer = new Customer();
            customer.CustomerID = Convert.ToInt32(columns[0]);
            customer.Name = columns[1];
            customers.Add(customer);
        }

        textIn.Close();
        return customers;
    }

InvoiceDB类

public static class InvoiceDB
{

    private const string Dir = @"";
    private const string Path = Dir + "Invoices.txt";

    public static List<Invoice> GetInvoices()
    {
        List<Invoice> invoices = new List<Invoice>();

        StreamReader textIn = new StreamReader(
            new FileStream(Path, FileMode.Open, FileAccess.Read));

        while (textIn.Peek() != -1)
        {
            string row = textIn.ReadLine();
            string[] columns = row.Split('|');
            Invoice invoice = new Invoice();
            invoice.InvoiceID = Convert.ToInt32(columns[0]);
            invoice.CustomerID = Convert.ToInt32(columns[1]);
            invoice.InvoiceDate = Convert.ToDateTime(columns[2]);
            invoice.ProductTotal = Convert.ToDecimal(columns[3]);
            invoice.SalesTax = Convert.ToDecimal(columns[4]);
            invoice.Shipping = Convert.ToDecimal(columns[5]);
            invoice.InvoiceTotal = Convert.ToDecimal(columns[6]);
            invoices.Add(invoice);
        }

        textIn.Close();
        return invoices;
    }

Answer 1

当ListView处于详细模式时，您应该定义ColumnHeaderCollection，添加要在ListView中显示的列。如果不定义ColumnHeaderCollection，ListView将显示为空

来自MSDN的评论解释了这一点

Columns属性返回一个集合，该集合包含在ListView控件中显示的ColumnHeader对象。当View属性设置为Details时，ColumnHeader对象定义在ListView控件中显示的列。每列用于显示ListView中每一项的子项信息。有关如何操作集合中的项的更多信息，请参见ListView.ColumnHeaderCollection。

您应该将列添加到ListView中，如下所示

lvInvoice.Columns.Add("Name", -2, HorizontalAlignment.Left);
lvInvoice.Columns.Add("ID", -2, HorizontalAlignment.Left);
lvInvoice.Columns.Add("Date", -2, HorizontalAlignment.Left);
lvInvoice.Columns.Add("Total", -2, HorizontalAlignment.Left);

有Add方法的many overloads，选择最适合您的任务