从Java和C＃中无法从非静态类访问静态方法

Question

Access static method from non static class with object. It is not possible in C#. Where it is done by JAVA. How it works?

example of java

/**
* Access static member of the class through object.
*/
import java.io.*;

class StaticMemberClass {
    // Declare a static method.
    public static void staticDisplay() {
        System.out.println("This is static method.");
    }
    // Declare a non static method.
    public void nonStaticDisplay() {
        System.out.println("This is non static method.");
    }
}

class StaticAccessByObject {

    public static void main(String[] args) throws IOException {
        // call a static member only by class name.
        StaticMemberClass.staticDisplay();
        // Create object of StaticMemberClass class.
        StaticMemberClass obj = new StaticMemberClass();
        // call a static member only by object.
        obj.staticDisplay();
        // accessing non static method through object.
        obj.nonStaticDisplay();
    }
}

Output of the program:

This is static method.
This is static method.
This is non static method.

How to do this in C#? thanks in advance..

Answer 1

C# forbids referencing a static method through instance.Method , only Type.Method is acceptable. To call a static method, you need to go through the type, not an instance.
In your case this means that StaticMemberClass.staticDisplay() works, but obj.staticDisplay() does not.

---

When a method is referenced in a member-access (§7.6.4) of the form EM , if M is a static method, E must denote a type containing M , and if M is an instance method, E must denote an instance of a type containing M .

(C# Language Specification Version 4.0 - 10.6.2 Static and instance methods)

When a static member M is referenced in a member-access (§7.6.4) of the form EM , E must denote a type containing M . It is a compile-time error for E to denote an instance.

(C# Language Specification Version 4.0 - 10.3.7 Static and instance members)

Answer 2

You can't. You'll need to use the actual class, in your case

StaticMemberClass.staticDisplay();

Answer 3

You could create an instance member to wrap the call to the static member. Or make the static member an instance member.