Can you use abstract and final both with a method? Why?

Short Answer: No. Long Answer: Let's take a closer look at both keywords separately and try to understand their purpose before understanding the Why part of the question. An abstract method is a common behavior for which, each subclass will provide its own concrete implementation (or Override the abstract method). For example, consider an abstract class called Shape having an abstract method called getArea(). The abstract method doesn't know exactly how the area of the underlying shape will be calculated. But it just knows that each subclass of Shape needs to have a getArea() method. The concrete classes will decide how to compute the area. That is, the getArea() method inside Circle class will return area based on radius; while Rectangle class will return area based on length and breath. Similarly, other sub-classes will have their own concrete implementations. Now , coming to final keyword. If a method is declared as final, then it implies that this is the final implementation of this method and its behavior should not be modified at runtime by any subclass. If a method is declared as final, it cannot be Overriden by any subclass. For example, consider the abstract class House with methods getWindowCount() and getDoorCount(). Now, irrespective of the type of house (i.e. villa, appartment, bunglow, etc.), the concrete implementation of the above mentioned methods is not going to change. Hence, we can declare these methods as final and provide a concrete implementation in the House class itself. Since, you don't want someone to accidentally change the behavior of counting the number of windows and doors in the house based on its type. Conclusion: There are separate design considerations while choosing between the keywords abstract and final. When used on a method, they have completely opposite purposes. And since, there purpose are so opposite to each other (abstract methods mean provide implementation in sub-classes; while final methods mean DO NOT provide implementation in sub-classes), hence, it doesn't make sense to use them together on a single method. This is the reason, why Java compiler doesn't allow the usage of abstract and final keywords on a method. It throws a compile time error "illegal combination of modifiers: abstract and final". read less