public static boolean isReverse(String string1, String string2) {
		/* not the same length */
		if (string1.length() != string2.length()) {
			return false;
		}
		if (string1.length() == 0 && string2.length() == 0) {
			return true;
		}

		/* compare two substrings */
		if (string1.charAt(0) == string2.charAt(string2.length() - 1)) {
			return isReverse(string1.substring(1),
					string2.substring(0, string2.length() - 1));
		}
		return false;
	}