Scala convert List[Int] to a java.util.List[java.lang.Integer]

Question

Is there a way in Scala to convert a List[Int] to java.util.List[java.lang.Integer]?

I\'m interfacing with Java (Thrift).

Answer 1

Because the underlying representation of Int is Integer you can cast directly to java.util.List[java.lang.Integer]. It will save you an O(n) operation and some implicit stuff.

import collection.JavaConversions._

class A {
  def l() = asList(List(1,2)).asInstanceOf[java.util.List[java.lang.Integer]]
}

Then you can use from Java like this:

A a = new A();
java.util.List l = a.l();

Note that on 2.9.0 ,I get a deprecation warning on asList (use seqAsJavaList instead)