### Question:
StringUtils { public static boolean isBlank(String str) { if (str == null || str.length() == 0) return true; return false; }  static boolean isBlank(String str); static boolean isEmpty(String str); static boolean isNotEmpty(String str); static boolean isInteger(String str); static int parseInteger(String str); static Map<String, String> parseQueryString(String qs); static String getServiceKey(Map<String, String> ps); static String toQueryString(Map<String, String> ps); static boolean isEquals(String s1, String s2); static boolean isContains(String values, String value); static boolean isContains(String[] values, String value); static boolean isNumeric(String str); static final String[] EMPTY_STRING_ARRAY; }### Answer:
@Test public void isBlank() throws Exception { assertTrue(StringUtils.isBlank(null)); assertTrue(StringUtils.isBlank("")); assertFalse(StringUtils.isBlank(" ")); assertFalse(StringUtils.isBlank("sxp")); }