How do I see if a class has an init block using reflection?

Question

If I have a Kotlin class like the following:

data class Foo(
    val count: AtomicInteger
) {
    init {
        count.incrementAndGet()
    }
}

How do I determine that this class has an init block using reflection?

The init block does not appear in Foo::class.members and I can't see a way of determining it from Foo::class.constructors.

Is there any way to find out information about the init block using kotlin.reflect?

I highly doubt this information is available after compilation. Init blocks and property initializers on JVM are compiled into some mixture of constructors and/or field initializers. It’s up to the compiler how it wants to do this in an optimal way. — Tenfour04, Sep 28 '21 at 21:24
@Tenfour04 thanks, I was hoping it would be somehow available in the Kotlin metadata and accessible using reflection but no luck so far — David Rawson, Sep 28 '21 at 21:28
@IR42 dealing with a legacy system that still uses Gson and can't be migrated any time soon :/ When Gson constructs an instance it doesn't run the init block, so I wanted to catch this somehow. — David Rawson, Sep 28 '21 at 21:46
Does Gson call a constructor? If so, then that will include anything needed in `init` blocks too. (Or if not, then that's probably the larger problem.) — gidds, Sep 28 '21 at 22:09
@gidds unfortunately Gson uses unsafe calls to construct the instance, so it is indeed a larger problem. — David Rawson, Sep 28 '21 at 22:13
@Tenfour04 I believe your comment is correct, if you change it into an answer I will accept it — David Rawson, Sep 29 '21 at 07:26

score 0 · Accepted Answer · answered Jul 20 '22 at 00:34

This information is not available after compilation.

Init blocks and property initializers on JVM are compiled into some mixture of constructors and/or field initializers. It’s up to the compiler how it wants to do this in an optimal way.

_{Answer courtesy of Tenfour04}

How do I see if a class has an init block using reflection?

1 Answers1