import java.util.stream.Collectors;
import java.util.stream.Stream;

class Ideone {
    public static void main(String[] args) {
        String[] params = {"v1", "v2"};
        StringBuilder sb = new StringBuilder();
        Stream.of(params).map(sb::append).collect(Collectors.toList());
        System.out.println(sb.toString());
    }
}