``` val Class<*>.boxed get() = if (isPrim...

# stdlib

[Marc Knaup]

val Class<*>.boxed
	get() =
		if (isPrimitive)
			when (this) {
				Boolean::class.java -> java.lang.Boolean::class.java
				Char::class.java -> java.lang.Character::class.java
				Byte::class.java -> java.lang.Byte::class.java
				Short::class.java -> java.lang.Short::class.java
				Int::class.java -> java.lang.Integer::class.java
				Long::class.java -> java.lang.Long::class.java
				Float::class.java -> java.lang.Float::class.java
				Double::class.java -> java.lang.Double::class.java
				Void.TYPE -> java.lang.Void::class.java
				else -> error("Unexpected primitive class: $this")
			}
		else
			this


fun Class<*>.isAssignableOrBoxableTo(otherClass: Class<*>) =
	otherClass.isAssignableOrBoxableFrom(this)


fun Class<*>.isAssignableOrBoxableFrom(otherClass: Class<*>) =
	boxed.isAssignableFrom(otherClass.boxed)

🤔
Would that be useful for stdlib?

[elizarov]

But what is the use-case? Why would one need this? In what kind of code / cases?

[Marc Knaup]

I’m writing a JSON encoder/decoder.
One encoder declared that it can encode Boolean::class.java but it encountered a java.lang.Boolean::class.java which was not reported as assignable (using Class.isAssignableFrom) and thus the encoder wasn’t used, although it could’ve been.

[Marc Knaup]

I wouldn’t expect anyone writing an encoder that they cannot use Boolean::class.java because it refers to the primitive type (there isn’t a distinction in Kotlin).
So it should work just fine, which it does with the code above.

[ilya.gorbunov]

Take a look at javaPrimitiveType/javaObjectType extensions functions on KClass, probably you can use them instead of boxed

[Marc Knaup]

Nice one, thanks! Why does it use string comparison though? Doesn’t that hurt performance?

Also, doesn’t work for `void`:
java.lang.Void.TYPE.kotlin ->

exception: java.lang.AssertionError: Non-primitive type name passed: void
	at kotlin.reflect.jvm.internal.impl.resolve.jvm.JvmPrimitiveType.get(JvmPrimitiveType.java:60)
	at kotlin.reflect.jvm.internal.RuntimeTypeMapper.getPrimitiveType(RuntimeTypeMapper.kt:279)
	at kotlin.reflect.jvm.internal.RuntimeTypeMapper.mapJvmClassToKotlinClassId(RuntimeTypeMapper.kt:266)
	at kotlin.reflect.jvm.internal.KClassImpl.getClassId(KClassImpl.kt:176)
	at kotlin.reflect.jvm.internal.KClassImpl.toString(KClassImpl.kt:271)

[Marc Knaup]

reported the error: https://youtrack.jetbrains.com/issue/KT-20875 😄