### Question:
StringUtils { public static String diff(String str1, String str2) { int index = str1.lastIndexOf(str2); if (index > -1) { return str1.substring(str2.length()); } return str1; } private  StringUtils(); static boolean isEmpty(String str); static Predicate<String> notEmpty(); static boolean isEmpty(List<String> list); static String diff(String str1, String str2); static String getFirstFound(String contents, String regex); static String addDefaultPortIfMissing(String urlString); static String addDefaultPortIfMissing(String urlString, String defaultPort); static String capitalize(String name); static String uncapitalize(String str); static byte[] toBytesUTF8(String str); static byte[] toBytesASCII(String str); static byte[] toBytes(String str, String enc); static String toHexString(byte[] bytes);  }### Answer:
@Test public void testDiff() throws Exception { String str1 = "http: String str2 = "http: String str3 = "http: assertEquals("/greetMe/me/CXF", StringUtils.diff(str1, str2)); assertEquals("greetMe/me/CXF", StringUtils.diff(str1, str3)); assertEquals("http: }