What is meant by a 'virtual method'?

Mallesham Karnati

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posted 20 years ago

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Hi,
I know about static and non-static methods in java. But, what is a 'virtual method' and why is it called so?

Ilja Preuss

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posted 20 years ago

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In C++ and C#, a virtual method is one that is polymorphic. In Java, all non-static method are virtual, all static methods aren't.

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Mallesham Karnati

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posted 20 years ago

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Thanks Ilja for your quick response. Could you please tell me why non-static methods are called 'virtual'? I am not able to figure out the significance of the term 'virtual' in this context.

Jeff Bosch

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posted 20 years ago

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Java doesn't use the virtual keyword directly. C++ and C# do. The Java compiler itself has a virtual mode by which it resolves references at runtime rather than at compile time. Is that what you're referring to?

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Ilja Preuss

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In many OO languages, polymorphism is implemented by the use of so-called "virtual jump tables". Basically, when a polymorphic method is called, the address of the code to execute is looked up in a table associated with the object. That's why polymorphic methods are also often called "virtual" in those languages.

Does that help?

Mallesham Karnati

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posted 20 years ago

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Thanks Ilja for your answer. Now I understad it clearly.

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