以下是示例代码中AttemptController中静态字段的含义是什么？

Question

我是一个C#的新手，正在尝试学习静态关键字。我不明白为什么我们需要两次初始化静态字段。按照我的理解，静态字段在程序执行期间保留值。

class Program
    {
        static void Main(string[] args)
        {

        AttemptController Obj = new AttemptController(3, 2);
        Console.WriteLine("Maximum:   {0}", AttemptController.MaxAttempts);
        Console.WriteLine("Warning:   {0}", AttemptController.WarningAttempts);
        Console.WriteLine("Threshold: {0}", AttemptController.Threshold);

        AttemptController Obj1 = new AttemptController(7, 5);
        Console.WriteLine("Maximum:   {0}", AttemptController.MaxAttempts);
        Console.WriteLine("Warning:   {0}", AttemptController.WarningAttempts);
        Console.WriteLine("Threshold: {0}", AttemptController.Threshold);
        Console.ReadLine();
    }

    class AttemptController
    {
        internal static int MaxAttempts;
        internal static int WarningAttempts;
        internal static int Threshold;

        public AttemptController(int a, int b)
        {
            MaxAttempts = a;
            WarningAttempts = b;
            Threshold = MaxAttempts - WarningAttempts;
        }
    }
}

- Pravin Wadkar

---

尝试将 AttemptController 类设为静态。 - jazb

AttemptController?? 这是MVC应用程序吗？如果是，那么拥有那些静态字段是无用的。 - Rahul

Answer 1

所以有几个建议更改：

• make the class static
• get rid of the constructor as static classes cannot have instance constructors.

• add a new method called init just for demo purposes.

  using System;
  
  namespace ConsoleApp4
  {
      internal class Program
      {
          private static void Main(string[] args)
          {
              AttemptController.Init(3, 2);
              Console.WriteLine("Maximum:   {0}", AttemptController.MaxAttempts);
              Console.WriteLine("Warning:   {0}", AttemptController.WarningAttempts);
              Console.WriteLine("Threshold: {0}", AttemptController.Threshold);
  
              AttemptController.Init(7, 5);
              Console.WriteLine("Maximum:   {0}", AttemptController.MaxAttempts);
              Console.WriteLine("Warning:   {0}", AttemptController.WarningAttempts);
              Console.WriteLine("Threshold: {0}", AttemptController.Threshold);
              Console.ReadLine();
      }
  }
  
      public static class AttemptController
      {
          internal static int MaxAttempts;
          internal static int WarningAttempts;
          internal static int Threshold;
  
  
  
          public static void Init(int a, int b)
          {
              MaxAttempts = MaxAttempts + a;
              WarningAttempts = WarningAttempts + b;
              Threshold = MaxAttempts - WarningAttempts;
          }
      }
  }
  

- jazb

Answer 2

因为你在构造方法中设置了MaxAttempts，WarningAttempts和Threshold字段。

当你使用AttemptController Obj = new AttemptController(3, 2);时，它将设置这些值。

当你使用时，将会设置MaxAttempts = 3和WarningAttempts = 2。

AttemptController Obj = new AttemptController(3, 2);

当您使用 MaxAttempts = 7 和 WarningAttempts = 5 时，将设置。

AttemptController Obj1 = new AttemptController(7, 5);

static字段允许所有实例使用相同的字段值。

- D-Shih