public boolean isPalindrome(String s) {
		if (s == null || s.equals(""))
			return true;
		s = s.toLowerCase();
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < s.length(); ++i) {
			if (s.charAt(i) >= 'a' && s.charAt(i) <= 'z') {
				sb.append(s.charAt(i));
			}
		}
		s = sb.toString();
		for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
			if (s.charAt(i) != s.charAt(j)) {
				return false;
			}
		}
		return true;
	}