### Question:
StringUtils { public static boolean isEmpty(String str) { if (str == null || str.length() == 0) { return true; } return false; }  static boolean isEmpty(String str); static boolean isNotEmpty(String str); static boolean hasText(String str); static boolean hasText(CharSequence str); static boolean hasChineseCharacter(String str); static String trim(String source);  }### Answer:
@Test public void isEmpty() throws Exception { assertTrue(StringUtils.isEmpty(null)); assertTrue(StringUtils.isEmpty("")); assertFalse(StringUtils.isEmpty(" ")); assertFalse(StringUtils.isEmpty("sxp")); assertFalse(StringUtils.isEmpty("施小平")); assertFalse(StringUtils.isEmpty("x小p")); }