如何使用组合框过滤我的列表框项目？

Question

如果之前有人问过这个问题，我深表歉意，但我已经很接近解决这个问题了，基本上，当我单击组合框时，它为我提供了 4 个选项来过滤列表框（全部、披萨、汉堡、杂物） Pizza、Burger 和 Sundry 是类别名称中的词。如何使我的列表框仅显示在组合框中选择的内容。

class InventoryItem
{

        public string CategoryName { get; set; }
        public string FoodName { get; set; }
        public double Cost { get; set; }
        public double Quantity { get; set; }

       public override string ToString()

    {
        return $"{CategoryName} - {FoodName}. Cost: {Cost:0.00}, Quantity: {Quantity}";

    }


}

public partial class MainWindow : Window
{

    public MainWindow()
    {
        InitializeComponent();
    }


    private void inventoryButton_Click(object sender, RoutedEventArgs e )
    {
        InventoryWindow wnd = new InventoryWindow();

        //Var filepath allows the code to access the Invenotry.txt from the bin without direclty using a streamreader in the code 
        var filePath = "inventory.txt";

        if (File.Exists(filePath))
        {
            // ReadAllLines method can read all the lines from the inventory.text file and then returns them in an array, in this case the InventoryItem
            var fileContents = File.ReadAllLines(filePath);
            foreach (var inventoryLine in fileContents)
            {

                // This makes sure our line has some content with a true or false boolean value, hence continue simply allows the code to continue past the if statment
                if (string.IsNullOrWhiteSpace(inventoryLine)) continue;

                //We can now Split a line of text in the inventory txt into segments with a comma thanks to the inventoryLine.Split
                var inventoryLineSeg = inventoryLine.Split(',');
                var inventoryItem = new InventoryItem();

                // if the code was succesful in trying to parse the text file these will hold the value of cost and quantity
                double cost;
                double quantity;

                // Assign each part of the line to a property of the InventoryItem
                inventoryItem.CategoryName = inventoryLineSeg[0];
                if (inventoryLineSeg.Length > 1)
                {
                    inventoryItem.FoodName = inventoryLineSeg[1];
                }
                if (inventoryLineSeg.Length > 2 & double.TryParse(inventoryLineSeg[2], out cost))
                {
                    inventoryItem.Cost = cost;
                }
                if (inventoryLineSeg.Length > 3 & double.TryParse(inventoryLineSeg[3], out quantity))
                {
                    inventoryItem.Quantity = quantity;
                }


                //Now able to add all the InventoryItem to our ListBox
                wnd.ListBox.Items.Add(inventoryItem);
            }
            wnd.ShowDialog();

        }
    }       
    private void foodMenuButton_Click(object sender, RoutedEventArgs e)
    {
        FoodMenuWindow wnd = new FoodMenuWindow();
        wnd.ShowDialog();
    }

    private void newOrderButton_Click(object sender, RoutedEventArgs e)
    {
        OrderWindow wnd = new OrderWindow();
        wnd.ShowDialog();
    }

    private void completedOrdersButton_Click(object sender, RoutedEventArgs e)
    {
        CompletedOrdersWindow wnd = new CompletedOrdersWindow();
        wnd.ShowDialog();
    }

    private void quitButton_Click(object sender, RoutedEventArgs e)
    {
        this.Close();
    }
}

}

Answer 1

您需要在分隔符, 上拆分正在读取的line。

var array = line.Split(',');

然后您可以访问索引array[2] 和array[3] 处的数字。

double firstNumber = double.Parse(array[2]);
double secondNumber = double.Parse(array[3]);

Answer 2

您可以通过使用File 类的静态ReadAllLines 方法在不显式使用StreamReader 的情况下执行此操作，该方法从文本文件中读取所有行并将它们返回到数组中。

然后，对于每一行，您可以使用 string 类的静态 Split 方法，该方法会将行拆分为一个或多个字符（在您的情况下我们将使用逗号）并返回一个数组。

接下来，我们可以根据分割线的内容生成一个新的InventoryItem。我喜欢每次都测试数组的长度，这样如果有一行缺少逗号，我们就不会遇到异常（换句话说，除非你知道，否则不要尝试访问数组中的索引存在）。

最后，我们可以将新的InventoryItem 添加到我们的ListBox。

注意：这假设您有一个 InventoryItem 类，例如：

class InventoryItem
{
    public string CategoryName { get; set; }
    public string FoodName { get; set; }
    public double Cost { get; set; }
    public double Quantity { get; set; }
    public override string ToString()
    {
        return $"{CategoryName} ({FoodName}) - Price: ${Cost:0.00}, Qty: {Quantity}";
    }
}

然后我们可以像这样解析文件并更新我们的ListBox：

// Path to our inventory file
var filePath = @"f:\public\temp\inventory.txt";

if (File.Exists(filePath))
{
    var fileContents = File.ReadAllLines(filePath);

    foreach (var inventoryLine in fileContents)
    {
        // Ensure our line has some content
        if (string.IsNullOrWhiteSpace(inventoryLine)) continue;

        // Split the line on the comma character
        var inventoryLineParts = inventoryLine.Split(',');
        var inventoryItem = new InventoryItem();

        // These will hold the values of Cost and Quantity if `double.TryParse` succeeds
        double cost;
        double qty;

        // Assign each part of the line to a property of the InventoryItem
        inventoryItem.CategoryName = inventoryLineParts[0].Trim();
        if (inventoryLineParts.Length > 1)
        {
            inventoryItem.FoodName = inventoryLineParts[1].Trim();
        }
        if (inventoryLineParts.Length > 2 && 
            double.TryParse(inventoryLineParts[2], out cost))
        {
            inventoryItem.Cost = cost;
        }
        if (inventoryLineParts.Length > 3 && 
            double.TryParse(inventoryLineParts[3], out qty))
        {
            inventoryItem.Quantity = qty;
        }

        // Add this InventoryItem to our ListBox
        wnd.ListBox.Items.Add(inventoryItem);
    }
}