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javascalascala-collectionsscala-2.7

Converting a Java collection into a Scala collection

Related to Stack Overflow question Scala equivalent of new HashSet(Collection) , how do I convert a Java collection (java.util.List say) into a Scala collection List?

I am actually trying to convert a Java API call to Spring's SimpleJdbcTemplate, which returns a java.util.List<T>, into a Scala immutable HashSet. So for example:

val l: java.util.List[String] = javaApi.query( ... )
val s: HashSet[String] = //make a set from l

This seems to work. Criticism is welcome!

import scala.collection.immutable.Set
import scala.collection.jcl.Buffer 
val s: scala.collection.Set[String] =
                      Set(Buffer(javaApi.query( ... ) ) : _ *)
Solution

  • Your last suggestion works, but you can also avoid using jcl.Buffer:

    Set(javaApi.query(...).toArray: _*)

    Note that scala.collection.immutable.Set is made available by default thanks to Predef.scala.