Does javac removes methods that are not referenced in the code?

Question

I have a code base and some methods are never used. Does javac remove the unused methods from the class file?

@larsmans: Why is it special for `public`? Is it because some other code might be using them? Can you elaborate? — noMAD, Mar 07 '12 at 22:35

score 8 · Accepted Answer · answered Mar 07 '12 at 22:35

Q: I want to know if I have a code base and some methods are never used. Does javac remove the unused methods from the class file?

A: No. What goes into the class, stays in the class file.

... however ...

The JVM loads only what's needed into memory. RAM isn't "wasted" on unused classes.

score 5 · Answer 2 · answered Mar 07 '12 at 22:33

5

No, it doesn't. To verify this, you can run

javap -c foo.bar.MyClass

and see all the code there. You can also access it via reflection (assuming you're running with appropriate permissions).

answered Mar 07 '12 at 22:33

Jon Skeet

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score 4 · Answer 3 · answered Mar 07 '12 at 22:36

No it doesn't and it can't. Think about what would happen if the compiler did that when you compile a library. All methods that the library wants to export for users, but doesn't use itself would be removed. And there is no way in Java to distinguish between something that is a library and your code.

Does javac removes methods that are not referenced in the code?

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