Predef.$eq$colon$eq<A,B>

[dali.mi...@gmail.com]

Hi,

I want to use a scala method with java. I need to pass Predef.$eq$colon$eq<A,B> argument. But I did not find any example to write Predef.$eq$colon$eq in java.

Can you help me please

[Bartek Hamielec]

Could you please provide more details? :)

Regards,
Bartek

[Oliver Ruebenacker]

     Hello,

  I think you cannot refer to it directly in Java, but you can write an adapter in Scala, like

object PredefAdapter {

  val eqColonEq = Predef.=:=

}

  and then refer to it in Java as PredefAdapter.eqColonEq.

     Best, Oliver

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Oliver Ruebenacker

Senior Software Engineer, Diabetes Portal, Broad Institute

[dali.mi...@gmail.com]

Hi,

I am using Graphx with java. I want to use the Graph.mapVertices() method and I need to pass Predef.$eq$colon$eq<VD,VD2> argument.

[Stephen Compall]

On 3/9/17 1:29 PM, dali.mi...@gmail.com wrote:

I am using Graphx with java. I want to use the Graph.mapVertices() method and I need to pass Predef.$eq$colon$eq<VD,VD2> argument.

Sure.

class Leibniz {
  static <T> scala.Predef.$eq$colon$eq<T, T> reflexivity() {
    return scala.Predef.$eq$colon$eq$.MODULE$.tpEquals();
  }
}

--
Stephen Compall

[dali.mi...@gmail.com]

Thank you,

I created a class Predef1:

public class Predef1 {

 static public <T> scala.Predef.$eq$colon$eq<T, T> reflexivity() {

   return scala.Predef.$eq$colon$eq$.MODULE$.tpEquals();

 }

}

and I use Predef1.reflexivity() to pass th argument but I have this error:

The method mapVertices(..., Predef.$eq$colon$eq<String,VD2>) is not applicable for the argument (..., Predef.$eq$colon$eq<Object,Object>)

I need to pass an argument Predef.$eq$colon$eq<String,VD2>

[Jasper-M]

I assume VD2 is a type variable?

Then you have to do either of these:

1) Pass the reference around:

public <VD1> void myGenericMethod(VD1 vd, $eq$colon$eq<String,VD1> ev) {

  mapVertices(..., ev);

}

public void myMethod() {

  String vd = "VD";

  myGenericMethod(vd, Predef1.reflexivity());

}

2) Cast the reference:

public <VD1> void myMethod() {

  Object obj = Predef1.reflexivity();

  scala.Predef.$eq$colon$eq<String,VD1> ev = (scala.Predef.$eq$colon$eq<String,VD1>) obj;

  mapVertices(..., ev);

}

Op vrijdag 10 maart 2017 10:07:19 UTC+1 schreef dali.mi...@gmail.com:

[Jasper-M]

s/VD1/VD2/g of course.

Op vrijdag 10 maart 2017 12:50:58 UTC+1 schreef Jasper-M: