7.12 Static methods

Static methods in C# are very similar to static methods in Java. You declare a static method using the static keyword. A static method belongs to the class as a whole, rather than to a single instance of the class.

Similiarly, you invoke a static method by prefixing the method name with the class name followed by a dot.

 1: using System;  2:  3: class MainClass{  4:   static void Main(){  5:  TestClass.DoSomething()  ;  6:   }  7: }  8:  9: class TestClass{ 10:  static  public void DoSomething (){ 11:     Console.WriteLine("running static method"); 12:   } 13: }

Output:

 c:\expt>test running static method

Like Java

A static method cannot refer to non-static methods or other non-static members .

Unlike Java

You cannot invoke a static method using a reference to an instance of that class. You need to use the class name to invoke a static method, or access a static member. Java allows you to invoke a static method using a variable referring to an instance of the class, as shown in the example below.

You can do this in Java:

 1: // TestMain.java  2: public class TestMain{  3:   public static void main(String args[]){  4:     TestClass c = new TestClass();  5:  c.doSomething();  // or TestClass.doSomething();  6:   }  7: }  8: class TestClass{  9:   public static void doSomething(){ 10:     System.out.println("running static method"); 11:   } 12: }

However in C#, this will give a compilation error:

 1: using System;  2: public class TestMain{  3:   public static void Main(){  4:     TestClass c = new TestClass();  5:  c.DoSomething();  // use TestClass.DoSomething();  6:   }  7: }  8: class TestClass{  9:   public static void DoSomething(){ 10:     Console.WriteLine("running static method"); 11:   } 12: }

Compilation error:

 Test.cs(4,5): error CS0176: Static member 'TestClass.DoSomething()' cannot be accessed with an instance reference; qualify it with a type name instead

Additional notes

The static keyword can be used with fields, methods, properties, operators, and constructors, but cannot be used with indexers, destructors, or types.
Static function members (methods, instance constructors, properties, and operators) are always non-virtual.
A static member cannot be declared with the following modifiers: virtual , override, and abstract .