Why aren't arithmetic operations working using the Eclipse Kotlin plug-in?

So I’ve decided to learn how code in Kotlin this morning on eclipse.
Whenever I try to do an arithmetic operation Im always met with this error :

ERROR: Cannot access ‘java.io.Serializable’ which is a supertype of ‘kotlin.Int’. Check your module classpath for missing or conflicting dependencies

This is the code I wrote (just testing the waters with this language )
fun main()

	val x : String= "cake 

	var y : String= "cookie" 
		y = "something new"

var z: Int=+77 

var nullvalues : Int ? = null 
var other = null 

println("the answer is : $z  ") 
println("the sum of 1 and 2 is ") //side note , if I add a string template after "is" like so ${1+2}  I get the error and sometimes I only get the string part in the console


I’ve tried every thing. I googled the error , reinstalled the plug in but Im quite lost.
So please if anyone could offer a fix that would be much appreciated !

I have the same type of problem and tracked it down to conflicting dependencies. It seems that the kotlin plugin itself is the cause. When you create a kotlin project and create you main class, you can see the conflict by import java.lang. and then press control-space. When you look at the list of suggestions then you will see all the definitions are duplicated.

This took me 8 hours to track down… :frowning_face: