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Why do we say that a static method in Java is not a virtual method?

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java

In object-oriented paradigm, a virtual function or virtual method is a function or method whose behavior can be overridden within an inheriting class by a function with the same signature to provide the polymorphic behavior.


According to the definition, every non-static method in Java is by default virtual method except final and private methods. The method which cannot be inherited for polymorphic behavior is not a virtual method.


An abstract class in Java is nothing but the pure virtual method equivalent to C++.


Why do we say that a static method in Java is not a virtual method? Even if we can override the static method and consequently it may give some advantages of the polymorphism and also a static method in Java can be invoked mostly with it's associated class name but it is also possible to invoke it using the object of it's associated class in Java in the same way that an instance method is invoked.

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Lion Avatar asked Nov 11 '11 14:11

Lion


People also ask

Why static methods Cannot be virtual?

Can Static Functions Be Virtual in C++? In C++, a static member function of a class cannot be virtual. Virtual functions are invoked when you have a pointer or reference to an instance of a class. Static functions aren't tied to the instance of a class but they are tied to the class.

Can we declare a static function as virtual in Java?

No, because it doesn't make any sense in C++. Virtual functions are invoked when you have a pointer/reference to an instance of a class. Static functions aren't tied to a particular instance, they're tied to a class.

Why there is no virtual function in Java?

The Virtual function cannot be private, as the private functions cannot be overridden. A virtual function or method also cannot be final, as the final methods also cannot be overridden. Static functions are also cannot be overridden; so, a virtual function should not be static.

Why static method is not overriden?

No, we cannot override static methods because method overriding is based on dynamic binding at runtime and the static methods are bonded using static binding at compile time. So, we cannot override static methods. The calling of method depends upon the type of object that calls the static method.


1 Answers

You can't override static methods. They are bound at compile-time. They are not polymorphic. Even if you try to invoke it as if it were an instance method (which IMO you shouldn't do) it's bound to the compile-time type of that expression, and the execution-time value is completely ignored (even if it's null):

Thread otherThread = null;
otherThread.sleep(1000); // No errors, equivalent to Thread.sleep(1000);

This behaviour can be very confusing for a reader, which is why at least some IDEs allow you to generate warnings or errors for accessing static members "through" a reference. It was a flaw in Java's design, pure and simple - but it doesn't make static methods virtual at all.

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Jon Skeet Avatar answered Sep 28 '22 05:09

Jon Skeet