Why MyClass::class.java.simpleName can't be constant value?

Question

A normal val is OK, and is initialized.

class MyClass {
    companion object {
        private val TAG = MyClass::class.java.simpleName
    }
}

But const val causes compilation error.

class MyClass {
    companion object {
        private const val TAG = MyClass::class.java.simpleName
    }
}

error log

MyClass.kt:27:33: error: const 'val' initializer should be a constant value
        private const val TAG = MyClass::class.java.simpleName

It seems unintuitive that simpleName cannot be defined as a const val.

Answer 1

In Kotlin, the const keyword should only be used when the value is a compile-time constant. Here MyClass::class.java.simpleName is not a compile-time constant. so we need to use val instead of const. val is same as the final keyword in Java.

For more info on this, please check here