StreamTest.java

public class Scratch implements EntryPoint {

  @Override
  public void onModuleLoad() {
    testStream(1, 2, 3);
  }

  private String createString(Integer n) {
    return "" + n;
  }

  private void testStream(Integer... numbers) {
    ArrayList<String> list = new ArrayList<>();
    Stream.of(numbers).map(this::createString).forEach(list::add);
    GWT.log(list.toString());
  }
}