java - How to make Kotlin stop casting argument to wrong class(Interface) -

i've been goofing around kotlin of recent, , it's been awesome!

i working twitter4j library tryout stuff twitter api. wrote code in kotlin

object demo {      private val twitterstream = twitterstreamfactory().instance     @jvmstatic     fun main(args: array<string>) {          val listener = object : statuslistener {              override fun onstallwarning(warning: stallwarning?) {                 println("got stall warning:" + warning)             }              override fun onscrubgeo(userid: long, uptostatusid: long) {                 println("got scrub_geo event userid:$userid uptostatusid:$uptostatusid")             }              override fun onstatus(status: status) {                 println("@" + status.user.screenname + " - " + status.text)             }              override fun ondeletionnotice(statusdeletionnotice: statusdeletionnotice) {                 println("got status deletion notice id:" + statusdeletionnotice.statusid)             }             override fun ontracklimitationnotice(numberoflimitedstatuses: int) {                 println("got track limitation notice:" + numberoflimitedstatuses)             }             override fun onexception(ex: exception) {                 ex.printstacktrace()             }         }          twitterstream.addlistener(listener)         twitterstream.sample()      } } 

but each time ran it, got exception in thread "main" java.lang.illegalaccesserror: tried access class twitter4j.streamlistener class co.enoobong.eno.twitter.bot.demo @ co.enoobong.eno.twitter.bot.demo.main(demo.kt:63)

upon further investigation, tools->kotlin->show kotlin bytecode. decompiled java, discover being generated.

 @jvmstatic  public static final void main(@notnull string[] args) {   intrinsics.checkparameterisnotnull(args, "args");   <undefinedtype> listener = new statuslistener() {      public void onstallwarning(@nullable stallwarning warning) {         string var2 = "got stall warning:" + warning;         system.out.println(var2);      }       public void onscrubgeo(long userid, long uptostatusid) {         string var5 = "got scrub_geo event userid:" + userid + " uptostatusid:" + uptostatusid;         system.out.println(var5);      }       public void onstatus(@notnull status status) {         intrinsics.checkparameterisnotnull(status, "status");         string var2 = "@" + status.getuser().getscreenname() + " - " + status.gettext();         system.out.println(var2);      }       public void ondeletionnotice(@notnull statusdeletionnotice statusdeletionnotice) {         intrinsics.checkparameterisnotnull(statusdeletionnotice, "statusdeletionnotice");         string var2 = "got status deletion notice id:" + statusdeletionnotice.getstatusid();         system.out.println(var2);      }       public void ontracklimitationnotice(int numberoflimitedstatuses) {         string var2 = "got track limitation notice:" + numberoflimitedstatuses;         system.out.println(var2);      }       public void onexception(@notnull exception ex) {         intrinsics.checkparameterisnotnull(ex, "ex");         ex.printstacktrace();      }   };   twitterstream.addlistener((streamlistener)listener);   twitterstream.sample(); 

}

kotlin trying cast listener streamlistener private in library (statuslistener extends it) hence illegalaccesserror

any ideas how resolve please?

ps: here's working java version of code - https://github.com/yusuke/twitter4j/blob/master/twitter4j-examples/src/main/java/twitter4j/examples/stream/printsamplestream.java

pps: i'm using kotlin 1.1.4, on intellij idea 2017.2.2

kotlin adds these casts ensure correct method called when dealing overloaded methods. problem occurs because public api addlistener expects package-private interface streamlistener. trying create such api causes warning because of problem , should fixed on twitter4j's side.

there no direct way fix in kotlin, can work around issue using java helper class , perhaps extension method:

class twitter4jfixer {     public static void addlistener(twitterstream stream, statuslistener listener) {         stream.addlistener(listener);     } }   fun twitterstream.addlistenerfixed(listener: statuslistener) {     twitter4jfixer.addlistener(this, listener) }