The use of override and virtual in C# vs. Java method overriding

Question

Why do we need to explicitly define a method as virtual and then also specify override in C# to accomplish method overriding whereas the same thing is achieved without using both of these in keywords in Java. What purpose does it serve?

Answer 1

in java, there's no need to add any keyword to override a method. But some rules apply:

• Methods overriding cannot be declared more private than the super class method.
• Any exceptions declared in overriding method must be of the same type as those thrown by the super class, or a subclass of that type.
• Methods declared as final cannot be overridden.
• An overriding method can be declared as final as the keyword final only suggests that this method cannot be further overridden.
• Methods declared as private cannot be overridden as they are not visible outside the class.

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Answer 2

This way you have tighter control over what's overrideable or not. It's the same as in access permissions - do you give a user all rights by default and remove permissions, or do you give none and then add what's required.