How can I use a Scala singleton object in Java?

Question

I have a Scala object that I need to use in a Java class.

Here's the Scala object

object Person {
  val MALE = "m"
  val FEMALE = "f"
}

How can I use this Scala object in Java?

I have tried the following so far without success (compile errors):

Person.MALE() //returns a String which is useless as I want the actual Person object

possible duplicate of How can I pass a Scala object reference around in Java? — om-nom-nom
– om-nom-nom, Commented Sep 5, 2012 at 14:55

Community · Accepted Answer · 2017-05-23 12:09:39Z

60

Use Person$.MODULE$. See also

Edit: A working example (I checked, it compiles and works): Scala:

object Person {
  val MALE = "m";
}

Java counterpart:

public class Test {
    Person$ myvar = Person$.MODULE$;

    public static void main(String argv[]) {
        System.out.println(new Test().myvar.MALE());
    }
}

edited May 23, 2017 at 12:09

CommunityBot

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answered Sep 5, 2012 at 14:50

Petr

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2 Comments

user786045 Over a year ago

This doesn't really work either. Eclipse tells me: Person$ cannot be resolved to a variable'code and the code doesn't compile

Hendrik Brummermann Over a year ago

@user786045, you need to add an import statement for Person$ manually. Eclipse does not add it automatically on "organize imports".

Sergey Tselovalnikov · Accepted Answer · 2017-04-19 05:27:18Z

1

In case you use a package object, the access is a bit different

Scala:

package my.scala.package

package object Person {
  val MALE = "m";
}

Java counterpart:

public static void main() {
  System.out.println(my.scala.package.Person.package$.MODULE$.MALE);
}

answered Apr 19, 2017 at 5:27

Sergey Tselovalnikov

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