# Valid Palindrome Runtime Error

• 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.

Why is there a runtime error?

public class Solution {
public static boolean isPalindrome(String s)
{
boolean result = false;

``````     if (s == "" || s == null)
{
result = true;
}
else
{
String lowerS = s.toLowerCase();
char[] _lowerS = lowerS.toCharArray();
int len = _lowerS.length;
int i = 0;
int j = len - 1;
while (i<j&&i<=len-1&&j>=0)
{
while ((_lowerS[i]>='a'&&_lowerS[i]<='z') == false)
i++;
while ((_lowerS[j]>='a'&&_lowerS[j]<='z') == false)
j--;
if ((_lowerS[i]== _lowerS[j])==false)
{
result = false;
break;
}
i++;
j--;
}
if (i == j+1 ||i ==j+2)
{
result = true;
}
}
return result;
}
``````

}

Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.