Can you override a static method c

Some time interviewer also ask, Why you can not override static methods in Java? The answer to this question lies in the time of resolution. As I said in the difference between static and dynamic binding , static methods are bonded during compile time using Type of reference variable, and not Object. If you have using IDE like Netbeans and Eclipse, and If you try to access static methods using an object, you will see warnings.

As per Java coding convention, static methods should be accessed by class name rather than an object. In short, a static method can be overloaded, but can not be overridden in Java. If you declare, another static method with same signature in derived class than the static method of superclass will be hidden, and any call to that static method in subclass will go to static method declared in that class itself.

This is known as method hiding in Java. Let's see an example of trying to override a static method. In this Java The program, we have two classes Parent and Child , both have name method which is static. Now, As per rules of method overriding , if a method is overridden than a call is resolved by the type of object during runtime. This means, in our test class StaticOverrideTest , p.

This happens, because static methods are resolved or bonded during compile time , and only information that is available, and used by the compiler is a type of reference variable. Since p was a reference variable of the Parent type, the name method from the Parent class was called.

Now, In order to prove that static method can be hidden, if we call Child. This means static methods can not be overridden in Java, they can only be hidden. This also answers, Why the static method can not be overridden in Java , because they are resolved during compile time. By the way, this example doesn't show, whether you can overload static method or not, but you can. See this tutorial, for an example of an overloading static method in Java. That's all on this Java interview question guys.

Remember, Static methods can not be overridden in Java , but they can be overloaded and hidden in Java. We have also touched based on What is method hiding in Java, and learned Why Static method can not be overridden in Java , since they are bonded during compile time by using a type of Class, and not at runtime using Objects.

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In answers to this question, the general consensus was that static methods are not meant to be overridden and thus static functions in C cannot be virtual or abstract. However, I can think of many examples of static functions that I'd want to override in a child class for example, factory methods.

While in theory, there are ways to get around them, none of them are clean or simple. That class determines the behavior of the overrides; it always gets the first crack at virtual methods. It can then choose to call parent method at the right time for it's implementation.

Each parent method then also gets its turn to invoke its parent method. This results in a nice cascade of parent invocations, which accomplishes one of the notions of reuse of code that object orientation is known for. Base classes can get reused by various subclasses, and each can coexist comfortably. Each class that is used to instantiate objects dictating its own behavior, peacefully and simultaneously coexisting with the others.

The client has control over which behaviors it wants and when by choosing which class to use to instantiate an object and pass around to others as desired. This is not a perfect mechanism, as one can always identify capabilities that are not supported, of course, which is why patterns like factory method and dependency injection are layered on top.

So, if we were to make an override capability for statics without changing anything else, we would have difficulty ordering the overrides. It would be hard to define a limited context for the applicability of the override, so you would get the override globally rather than more locally like with objects. There is no instance object to switch the behavior.

So, if someone invoked the static method that happened to have been overridden by another class, should the override get control or not? If there are multiple such overrides, who gets control first? With instance object overrides, these questions all have meaningful and well-reasoned answers, but with statics they do not.

Overrides for statics would be substantially chaotic, and, things like this have been done before. For example, the Mac OS System 7 and prior used a trap patching mechanism for extending the system by getting control of application-made system calls before the operating system. You could think of the system call patch table as an array of function pointers, much like a vtable for instance objects, except that it was a single global table.

This caused untold grief for programmers because of the unordered nature of the trap patching. Whoever got to patch the trap last basically won, even if they didn't want to.

Each patcher of the trap would capture the previous trap value for a sort-of parent call capability, which was extremely fragile. Removing a trap patch, say when you no longer needed to know about a system call was considered bad form as you didn't really have the information needed to remove your patch if you did it you would also unpatch any other patches that had followed you.

This is not to say that it would be impossible to create a mechanism for overrides of statics, but what I would probably prefer to do instead is turn the static fields and static methods into instances fields and instance methods of metaclasses, so that the normal object orientation techniques would then apply.

Note that there are systems that do this as well: CSE Smalltalk classes and metaclasses ; See also: What is the Smalltalk equivalent of Java's static? I'm trying to say that you would have to do some serious language feature design to make it work even reasonably well.

For one example, a naive approach was done, did limp along, but was very problematic, and arguably i. I would argue architecturally flawed by providing an incomplete and difficult to use abstraction. So, there is no reason not to do this -- and some languages actually do. Perhaps it is just a bit more of a fringe requirement that a number of languages choose not to do.

Overriding depends on virtual dispatch: you use the runtime type of the this parameter to decide which method to call. A static method has no this parameter, so there's nothing to dispatch on.

Some languages, notably Delphi and Python, have an "in-between" scope that allows for this: class methods. Take our short survey.

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You can't override static methods. You can overload them which is what you're doing here , but you're just getting static dispatch. I get: 'Bar' member names cannot be the same as their enclosing types if I apply your first example. Bar can't even work. Add a comment. Lee Taylor 6, 14 14 gold badges 28 28 silver badges 43 43 bronze badges. Neel Neel It's slightly bit up level for me to digest, but along the way I will get it : PS: And I definitely want to be in your class in that case.

Found this post too in Java context. Some reasons to use static methods: They are a little bit faster than instance methods. Also see this msdn article which gives performance numbers to back this up inlined static call avg 0. Community Bot 1 1 1 silver badge. I have no issues with instance methods. I learnt that static Class can't be instantiated.

But you mentioned that "static methods is that it is instantiated only once in your app".. So I am confused now. Are you referring to Using System. Math; by saying static methods are instantiated? I have been using Math class members Math. Abs multiple times in the same class without instantiating them even once. Does it make sense to Sub-Class a static class? I shouldnt have used the term "instantiated" with a static method.

All methods are only "created" once. Even non-static methods have only one copy of the code in existence IL code which is created at compile-time and converted into machine code once at run-time. Do not confuse code and data! A non-static method is only callable via an instance of an object, but that is because of the hidden "this" pointer which is passed to it. The code itself is "static" in that it's fixed and singleton.

MatthewWatson thanks for the correction.