CODEWITHSUNDEEP
javacompiler-optimizationsoftware-design
user0000001
user0000001

Reputation: 2233

When creating multiple instances of the same object, does Java replicate the method implementations?

I've tried searching around for my answer but can't seem to find one.

I was curious if Java and or other modern languages optimize the replication of objects by doing some sort of virtual mapping for the methods. It would seem to be a waste if every time a new instance of a object is created, it would copy the methods associated with it rather then perhaps mapping these to one place in memory.

I can see some cases, such as polymorphism, where it might not work.

This might be more of a fundamentals question but I am very curious how the compiler handles this.

Thanks!

Upvotes: 1

Views: 183

Answers (1)

slim
slim

Reputation: 41263

Strictly speaking, it's none of your business:

The Java Virtual Machine does not mandate any particular internal structure for objects.

(JVM Spec)

So, if you were to write your own JVM, and for some reason you chose to put a copy of method code into every in-memory representation of an object, you would be free to do so.

However, there are various aspects of how the language is defined, that mean that it's not possible for two objects of the same class to have methods that differ -- even if they're non-static inner classes, dynamic classes, etc.

Therefore you're right that it would be wasteful of space to duplicate the method code for each instance, and no serious implementation of Java does so.

Upvotes: 1

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