125-Valid-Palindrome.java

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