[Leetcode][JAVA] Valid Palindrome

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.

Note:
Have you consider that the string might be empty? This is a good question to ask during an interview.

For the purpose of this problem, we define empty string as valid palindrome.

应该算是leetcode上最简单的题之一了吧。双指针可搞定。。

     public boolean isPalindrome(String s) {
         int i=0;
         int j=s.length()-1;
         while(i<j) {
             if(!Character.isLetterOrDigit(s.charAt(i))) {
                 i++;
                 continue;
             }
             if(!Character.isLetterOrDigit(s.charAt(j))) {
                 j--;
                 continue;
             }
             if(Character.toLowerCase(s.charAt(i))!=Character.toLowerCase(s.charAt(j)))
                 return false;
             i++;
             j--;
         }
         return true;
     }