calling finalize() of super class in Kotlin

Question

I have the following Java code I wanted to convert into Kotlin:

@Override
protected void finalize() throws Throwable {
    try {
        release();
    } finally {
        super.finalize();
    }
}

In the official documentation I have found this:

protected fun finalize() {
    // finalization logic
}

I use that like this:

protected fun finalize(){
    try{
        release()
    }finally {
        super.finalize()   <--- But Android Studio does not recognize finalize()
    }
}

Is it ok when I just delete super.finalize()? I have read the following SO threads but could not find a solution:

• How to implement finalize() in kotlin?
• Kotlin super.finalize()

Answer 1

There is no super.finalize() method to call because you are subclassing Any, not Object. Any doesn't have a finalize() method. You wouldn't need to do this for Object in Java either, because the base implementation doesn't do anything.

Answer 2

You should never rely on finalize but make your class AutoCloseable instead. There is no guarantee your finalize method will be called, it is slow and may introduce security issues. Note finalize has been already deprecated in Java9 (https://docs.oracle.com/javase/9/docs/api/java/lang/Object.html).

For AutoCloseable, Check https://docs.oracle.com/javase/8/docs/api/java/lang/AutoCloseable.html

Then you'll be able to use use in Kotlin:

class MyClass: AutoCloseable {
    override fun close() {
        // Release here
    }
}

fun main() {
    MyClass().use {
        // Do the work, close will be called for you
    }
}