CODEWITHSUNDEEP
javamethodssuper
user447607
user447607

Reputation: 5469

Will the JVM / Compiler optimize a simple super method call?

So if I have

public void methodName() {
super.methodName();
}

How will the Compiler / JVM handle this? Will it be treated the same as if the override never happened assuming the signatures are identical? I want to put this bit of code in as a clarification of intent so that folks don't wonder why hashCode() wasn't implemented in the same class as equals()

If it makes a difference to the system though, maybe not.

Upvotes: 4

Views: 197

Answers (1)

Holger
Holger

Reputation: 298143

Well, often the question “Can the JVM / Compiler optimize this particular method call?” is different from “Will it optimize said call?”, but your actual question is a different one.

Your real question is “Should I worry about the performance of this delegation call?” and that’s much easier to answer as it is a clear “No, don’t worry”.

First of all, regardless of whether a method invocation gets special treatment by the optimizer or not, the cost of a single invocation is negligible. It really doesn’t matter.

The reason, why optimizations of invocations are ever discussed, is not that the invocation itself is so expensive, but that inlining a method invocation enables follow-up optimizations by analyzing the caller’s code and the callee’s code as a unit. Obviously, this isn’t relevant to the trivial code of your overriding method. It only becomes relevant if the optimizer is going to take the caller’s context into account and if such an inlining operation happens, that single delegation step is indeed no match to the optimizer. The result of such an optimization will indeed be “as if the override never happened” (which applies to a lot of not so trivial scenarios as well).

But if that ever happens, depends on several surrounding conditions, including the question whether the code is a performance relevant hot spot. If not, it might happen that a call doesn’t get optimized, but that still shouldn’t bother you, because, well, it’s not performance relevant then.

Upvotes: 1

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