### Question:
StringUtil { public static boolean isWhitespace(int c){ return c == ' ' || c == '\t' || c == '\n' || c == '\f' || c == '\r'; }  static String join(Collection strings, String sep); static String join(Iterator strings, String sep); static String padding(int width); static boolean isBlank(String string); static boolean isNumeric(String string); static boolean isWhitespace(int c); static boolean isActuallyWhitespace(int c); static String normaliseWhitespace(String string); static void appendNormalisedWhitespace(StringBuilder accum, String string, boolean stripLeading); static boolean in(String needle, String... haystack); static boolean inSorted(String needle, String[] haystack); static URL resolve(URL base, String relUrl); static String resolve(final String baseUrl, final String relUrl); static StringBuilder stringBuilder();  }### Answer:
@Test public void isWhitespace() { assertTrue(StringUtil.isWhitespace('\t')); assertTrue(StringUtil.isWhitespace('\n')); assertTrue(StringUtil.isWhitespace('\r')); assertTrue(StringUtil.isWhitespace('\f')); assertTrue(StringUtil.isWhitespace(' ')); assertFalse(StringUtil.isWhitespace('\u00a0')); assertFalse(StringUtil.isWhitespace('\u2000')); assertFalse(StringUtil.isWhitespace('\u3000')); }