靜態和密封類差異

Question

1. 有沒有在靜態類中實現的類？ 方法：

    static class ABC : Anyclass

2. 是否有任何類可以在密封類和靜態類中繼承？
   方法：

    static class ABC : AClass {}

   和

   sealed class ABC : AClass {}

我可能在某種程度上是錯的嗎？

Answer 1

這可能會幫助您：

+--------------+---+-------------------------+------------------+---------------------+
|  Class Type  |   | Can inherit from others | Can be inherited | Can be instantiated | 
|--------------|---|-------------------------+------------------+---------------------+
| normal       | : |          YES            |        YES       |         YES         |
| abstract     | : |          YES            |        YES       |         NO          |
| sealed       | : |          YES            |        NO        |         YES         |
| static       | : |          NO             |        NO        |         NO          |
+--------------+---+-------------------------+------------------+---------------------+

Answer 2

簡單來說

靜態類

一個類可以聲明為靜態的，表明它只包含靜態成員。 無法使用 new 關鍵字創建靜態類的實例。 加載包含類的程序或命名空間時，.NET Framework 公共語言運行時 (CLR) 會自動加載靜態類。

密封類

密封類不能用作基類。 密封類主要用於防止派生。 因為它們永遠不能用作基類，所以一些運行時優化可以使調用密封類成員的速度稍快一些。

Answer 3

您可以讓sealed類從另一個類繼承，但不能從sealed類繼承：

sealed class MySealedClass : BaseClass // is ok
class MyOtherClass : MySealedClass     // won't compile

static類不能從其他類繼承。

Answer 4

您可以簡單地將它們區分為：

       Sealed Class       |        Static Class
--------------------------|-------------------------
it can inherit From other | it cannot inherit From other
classes but cannot be     | classes as well as cannot be
inherited                 | inherited

Answer 5

簡單的回答是密封類不能用作基類。

我試圖向您展示密封類是下面代碼中的派生類

 public sealed class SealedClass : ClassBase
{
    public override void Print()
    {
        base.Print();
    }
}

另一個密封特性只能通過它的實例訪問。（你不能從它繼承）

 class Program
{
    static void Main(string[] args)
    {
        SealedClass objSeald = new SealedClass();
        objSeald.Name = "Blah blah balh";
        objSeald.Print();

    }
}

Answer 6

public class BaseClassDemo
{ 

}

//Note
//A static class can be used as a convenient container for sets of 
//methods that just operate on input parameters and do not have to 
//get or set any internal instance fields.
//The advantage of using a static class is that the compiler can 
//check to make sure that no instance members are accidentally 
//added. The compiler will guarantee that instances of this class 
//cannot be created.


//Static class 'static type' cannot derive from type 'type'. Static 
//classes must derive from object.
 public static class StaticClassDemo : BaseClassDemo //Error



public static class StaticClassDemo
{
    //Static class must have static members
    public static void Ram()
    {
         throw new NotImplementedException();
    }
}


//Sealed class can inherit from the base class.
public sealed class SealedClassDemo : BaseClassDemo
{

}

//We can't derive from sealed class. 
public class derivedClass:SealedClassDemo //Error



public partial class RandomClass2
{
    //we can't create instance of static class.
    StaticClassDemo demo = new StaticClassDemo() //Error
}

Answer 7

1 - 不，您不能實現靜態類。

2 - 不，您不能從靜態或密封類繼承