Collection filter by Xtend closure

CollectionFilter.xtend

import java.util.List
import static extension java.util.Collections.*

class CollectionFilter {

    def static void main(String[] _) {

    val values = new ArrayList( 1, 5, 33, 0, -2, -10, 4, 36, -82 )
        positiveOnly( values )
        negativeOnly( values )
    }

    def static positiveOnly( List<Integer> values ) {
        values.filter( v| v >= 0 )
        println( values )
    }

    def static negativeOnly( List<Integer> values ) {
        values.filter( v| v < 0)
        println( values )
    }

}