Why should virtual functions not be used excessively?

Question

I just read that we should not use virtual function excessively. People felt that less virtual functions tends to have fewer bugs and reduces maintenance.

What kind of b

Answer 1

In Java, there is no virtual keyword, but all methods (functions) are virtual, except the ones marked as final, static methods and private instance methods. Using virtual functions is not a bad practice at all, but because generally they cannot be resolved in compile-time, and compiler can't perform optimizations on them, they tend to be a little slower. The JVM has to figure out at run-time, which is the exact method that needs to be called. Note that this is not a big problem by any means, and you should consider it only if your goal is to create a very high-performance application.

For example, one of the biggest optimizations in Apache Spark 2 (which runs on JVM) was to reduce number of virtual function dispatches, to gain a better performance.