### Question:
StringUtils { public static boolean isSameStr(String a, String b) { if (a == null && b != null) { return false; } if (a == null && b == null) { return true; } return a.equals(b); }  static boolean isEmpty(String str); static boolean isSameStr(String a, String b); static String setToStr(Set<String> stringSet, String delimiter); static String setToStr(Set<String> stringSet, String delimiter, String defaultRet); static Set<String> strToSet(String str, String delimiter); static List<String> strToList(String str, String delimiter); static boolean startWithToLowerCase(String thisString, String anotherString); static final String EMPTY_STRING; static final int CHAR_A; static final int CHAR_Z; static final int CASE_GAP; }### Answer:
@Test public void testSameStr() { Assert.assertTrue(StringUtils.isSameStr(null, null)); Assert.assertFalse(StringUtils.isSameStr(null, "")); Assert.assertFalse(StringUtils.isSameStr(null, "a")); Assert.assertFalse(StringUtils.isSameStr("aa", null)); Assert.assertFalse(StringUtils.isSameStr("aa", "")); Assert.assertFalse(StringUtils.isSameStr("aa", "a")); Assert.assertTrue(StringUtils.isSameStr("aa", "aa")); }