Hi all what am I missing here

Question

bodiam · Answer

I ve converter the above Java code to the following Kotlin code

jacob · Answer

what s the problem you re seeing

bodiam · Answer

class ProductRandomizerProvider RandomizerProvider override fun getRandomizerByField field Field context RandomizerContext Randomizer lt gt if field name == name amp amp context currentRandomizationDepth == 0 return product as Randomizer lt gt if field name == name amp amp context currentField == owner return owner as Randomizer lt gt return null

bodiam · Answer

But when I use this code using Java 11 I get the following error

bodiam · Answer

Caused by java lang ClassCastException class random RandomizerProviderTestsKotlin$testCustomRandomizerProvider$parameters$1$getRandomizerByField$1 cannot be cast to class org jeasy random api Randomizer random RandomizerProviderTestsKotlin$testCustomRandomizerProvider$parameters$1$getRandomizerByField$1 and org jeasy random api Randomizer are in unnamed module of loader app at random RandomizerProviderTestsKotlin$testCustomRandomizerProvider$parameters$1 getRandomizerByField Test kt 58

bodiam · Answer

When I run the Java code using Java 11 all is fine

bodiam · Answer

The thing the JVM is complaining about is this line

bodiam · Answer

return foo as Randomizer lt gt

bodiam · Answer

< jacob> sorry wasn t done typing yet wink

jacob · Answer

haha I asked too quickly stuck out tongue

jacob · Answer

I don t know that you can cast to `Randomizer lt gt `

jacob · Answer

nah that s not it

bodiam · Answer

I didn t know either but that s what IntelliJ made of it

bodiam · Answer

I m not sure if you can cast to it really but I also don t know an alternative

jacob · Answer

```class Field fun getName = class RandomizerContext fun getCurrentRandomizationDepth = 0 fun getCurrentField = class Randomizer lt T gt fun getRandomizerByField field Field context RandomizerContext Randomizer lt gt return custom randomizer based on the context if field getName equals name amp amp context getCurrentRandomizationDepth === 0 return foo if field getName equals name amp amp context getCurrentField equals bestFriend return bar return null ```

jacob · Answer

with that code I get

bodiam · Answer

yep

bodiam · Answer

Field btw is import java lang reflect Field

jacob · Answer

oh cool one tick

jacob · Answer

so I wonder if Java 11 prevents you casting a function to a class or an inline class or whatever bytecode KT takes lambdas to

bodiam · Answer

this is the original source code btw <https raw githubusercontent com j easy easy random dc947b5fe10681084497701f9654688d235955e1 easy random core src test java org jeasy random parameters RandomizerProviderTests java>

bodiam · Answer

I don t know I first thought it was an Java 11 issue but the code runs fine in the original context

jacob · Answer

the other thing I can see if the module error so maybe something around java 9 modules and kt

bodiam · Answer

but when I use Java 11 nope

jacob · Answer

which suggests something like <https github com jmockit jmockit1 issues 553> as a possibility

bodiam · Answer

I have no idea I tried doing some add module parameters on jeasy but that didn t do anything

bodiam · Answer

but that s private fields That doesn t seem to be related I think

jacob · Answer

<https stackoverflow com questions 54536895 cannot be cast to class because they are in unnamed module of loader app comment96026301 54536895> suggests also that module error is unrelated

bodiam · Answer

I looked at this one though <https github com mockk mockk issues 150>

bodiam · Answer

right So basically that code says can t case to Randomizer lt gt

bodiam · Answer

that might make sense But how to fix

jacob · Answer

possible that <https github com j easy easy random blob master easy random core src main java org jeasy random api Randomizer java L32> is the issue I m not sure what that annotation does but likely it marks the java class as being a function in same sense

jacob · Answer

so the java function returns gt which is the same as whatever that functionalInterface annotation generates

jacob · Answer

but the kt lambda doesn t generate a java lambda maybe

bodiam · Answer

functionalinterface is just a marker interface

bodiam · Answer

it means it s an interface with 1 abstract method

jacob · Answer

suggests that lambda s can inhabit a functionalinterface my best guess is that if is accurate KT compiles a lambda to a class that is not castable since it isn t a java8lambda

bodiam · Answer

but if you look here <https medium com tompee idiomatic kotlin lambdas and sam constructors fe2075965bfb>

bodiam · Answer

you can see that this is exactly how things should work

jacob · Answer

does ```fun getRandomizerByField field Field context RandomizerContext Randomizer lt gt return custom randomizer based on the context if field getName equals name amp amp context getCurrentRandomizationDepth === 0 return object Randomizer lt Any gt override val randomValue = foo if field getName equals name amp amp context getCurrentField equals bestFriend return object Randomizer lt Any gt override val randomValue = bar return null ``` work

jacob · Answer

bodiam · Answer

let me check

bodiam · Answer

It works a little bit

bodiam · Answer

The code you provided doesn t compile but with your pointer I ve created this

bodiam · Answer

return Randomizer lt Any gt product

jacob · Answer

haha a little bit

bodiam · Answer

I know I know wink

jacob · Answer

oh yeah that makes more sense

bodiam · Answer

and the original error is now gone I just have a new error now slightly smiling face

bodiam · Answer

Caused by java lang IllegalArgumentException Primitive types can t be instantiated in Java

bodiam · Answer

thing is I don t see primitives types in my code slightly smiling face

jacob · Answer

man that s strange

jacob · Answer

sorry that s about as far as I can think short of going through the bytecode of the kotlin program and the java program

bodiam · Answer

I ve found the primitive type now

bodiam · Answer

it s the byte array inside the string

jacob · Answer

oh wow

bodiam · Answer

that s not correct

bodiam · Answer

I don t think this code is correct

jacob · Answer

the lambda casting

bodiam · Answer

the return Randomizer xxx

bodiam · Answer

but it might have been a different issue

bodiam · Answer

I think the code works now

bodiam · Answer

class ProductRandomizerProvider RandomizerProvider override fun getRandomizerByField field Field context RandomizerContext Randomizer lt gt if field name == name amp amp context currentRandomizationDepth == 0 return Randomizer product if field name == name amp amp context currentField == bla return Randomizer xxx return null

bodiam · Answer

I need to dive a bit more into it to see if it s 100 correct or if the code just passes because I have another mistake

bodiam · Answer

but thanks for your help Jacob

bodiam · Answer

do you mind if I shout out your name on my blogpost for helping me out

bodiam · Answer

this post <https www jworks io easyrandom 4 0 released >

jacob · Answer

hey that s wonderful

jacob · Answer

no don t mind at all

jacob · Answer

really cool result I actually got to learn a bunch about how all this stuff works now

bodiam · Answer

cool I ll officially publish the post on Monday on Reddit and that stuff so I ll update the post later with an updated example

bodiam · Answer

thanks again for helping me out appreciate it

jacob · Answer

no worries slightly smiling face

bodiam · Answer

updated

karelpeeters · Answer

I m curious why casting a lambda to a random interface should work at all behind the scenes a lambda is just another class with an invoke function it doesn t magically implement the interface

Dico · Answer

It looks like you re importing the wrong `Randomizer` in one of your source files