LangUtils { public static String join(List<String> list, String separator) { return enquoteAndJoin(list, separator, "", ""); }  static List<T> repeat(T element, int number); static String join(List<String> list, String separator); static String enquoteAndJoin(Iterable<String> list,
            String separator, String prefix, String suffix); static String enquoteAndJoin(String[] list,
            String separator, String prefix, String suffix);  }
@Test public void join() { assertEquals("A,B,C", LangUtils.join(asList("A", "B", "C"), ",")); }