c# - 从 CSV 文件读取到对象列表

Question

我需要读取这个 CSV 文件并将其转换为 List<Vehicle>对象(汽车和自行车)，第一行必须被忽略，第三个值是对象的类型:

Name price typeOfVehicle Horsepower NumberOfPedals
Audi,100000,Car,500,
BMW,20000,Car,300
Abici,1000,Bicycle,,2
Atala,2000,Bicycle,,2

到目前为止我的代码:

abstract class Vehicle
    {
        public string Name { get; set; }
        public int Price { get; set; }
    }

    class Car : Vehicle
    {
        public int Horsepower { get; set; }
    }

    class Bicycle : Vehicle
    {
        public int NumberOfPedals { get; set; }
    }

    static class Offers
    {
        public  List<Vehicle> itemlist = new List<Vehicle>();
        public static void readfromfile()
        {
            var lines = System.IO.File.ReadAllLines("C:\\Offers.csv");

            foreach (string item in lines)
            {
                var values = item.Split(',');
                //need to check which type of vehicle is it
                if (values[2] == "Car")
                {
                    itemlist.Add(new Car()
                    {
                        Name = values[0],
                        Price = int.Parse(values[1]),
                        Horsepower = int.Parse(values[3])
                    });
                }
                else if (values[2] == "Bicycle")
                {
                    itemlist.Add(new Bicycle()
                    {
                        Name = values[0],
                        Price = int.Parse(values[1]),
                        NumberOfPedals = int.Parse(values[3])
                    });
                }

            }
        }
    }

我想从 CSV 文件中读取，读取时我需要检查每一行第三个值是汽车还是自行车。如果它是一辆汽车，那么我创建汽车对象(并将所有值赋予属性)并将其放入 Vehicles 列表中，自行车也是如此。

我收到关于 itemlist 的错误:

an object reference is required for the nonstatic field 'Offers.itemlist

最终解决方案:

abstract class Vehicle
    {
        public string Name { get; set; }
        public int Price { get; set; }
    }

    class Car : Vehicle
    {
        public int Horsepower { get; set; }
    }

    class Bicycle : Vehicle
    {
        public int NumberOfPedals { get; set; }
    }

    static class Offers
    {
        public static List<Vehicle> itemlist = new List<Vehicle>();
        public static void readfromfile()
        {
            var lines = System.IO.File.ReadAllLines("C:\\Offers.csv").Skip(1).TakeWhile(t => t != null);

            foreach (string item in lines)
            {
                var values = item.Split(',');
                //need to check which type of vehicle is it
                if (values[2] == "Car")
                {
                    itemlist.Add(new Car()
                    {
                        Name = values[0],
                        Price = int.Parse(values[1]),
                        Horsepower = int.Parse(values[3])
                    });
                }
                else if (values[2] == "Bicycle")
                {
                    itemlist.Add(new Bicycle()
                    {
                        Name = values[0],
                        Price = int.Parse(values[1]),
                        NumberOfPedals = int.Parse(values[3])
                    });
                }

            }
        }
    }

Answer 1

您做错的一件事是您将“item”类型的对象添加到 itemlist 而不是您在上面的行中声明的汽车或自行车。

发现的另一个问题是，最初您的列表声明中没有 static 修饰符。没有它，您需要一个类的实例(即不是静态的)。要使此类可实例化，您需要从类及其所有字段、属性和方法中删除静态修饰符。

https://learn.microsoft.com/en-us/dotnet/articles/csharp/programming-guide/classes-and-structs/static-classes-and-static-class-members

static class Offers
{
    public static List<Vehicle> itemlist = new List<Vehicle>();
    public static void readfromfile()
    {
        var lines = System.IO.File.ReadAllLines("C:\\Offers.csv");

        foreach (string item in lines)
        {
            var values = item.Split(',');
            //need to check which type of vehicle is it
            if(values[2] == "Car")
            {
                itemlist.Add(new Car()
                {
                    Name = values[0],
                    Price = int.Parse(values[1]),
                    Horsepower = int.Parse(values[3])
                });
            }
            else if (values[2]=="Bicycle")
            {
                itemlist.Add(new Bicycle()
                {
                    Name = values[0],
                    Price = int.Parse(values[1]),
                    NumberOfPedals= int.Parse(values[3])
                });
            }

        }
    }
}