StringUtils { public static String join(char separator, String... parts) { return join(CharBuffer.wrap(new char[] { separator }), parts); }  static String join(char separator, String... parts); static String join(CharSequence separator, String... parts);  }
@Test public void testJoinNullStrings() { assertEquals("null,null", StringUtils.join(',', null, null)); }
@Test public void testJoinStringsWithSeparatorChar() { assertEquals("a,b", StringUtils.join(',', "a", "b")); }
@Test public void testJoinStringsWithSeparatorSeq() { assertEquals("a..b", StringUtils.join("..", "a", "b")); }