Is Sentence Palindrome

IsSentencePalindrome.java

//In Place algorithm
//A man, a plan, a canal: Panama
 
public class Solution {
  
  public static void main(String[] args){
    
    String str = "A,,, man, a;; plan, a c....anal: Panama";
    boolean retVal = isPalindrome(str);
    
    System.out.println(retVal);
    
  }
  
  public static boolean isPalindrome(String s) {
    if (s.length() <= 1) return true;

    int head = 0;
    int tail = s.length()-1;
    
    while (head < tail){
      while (!Character.isLetterOrDigit(s.charAt(head))){
        head++;
      }
      while (!Character.isLetterOrDigit(s.charAt(tail))){
        tail--;
      }
      if (Character.toLowerCase(s.charAt(head)) != Character.toLowerCase(s.charAt(tail))){
        return false;
      }
      head++;
      tail--;
    }

    return true;
  }
}

//Alternate, using StringBuffer
//A man, a plan, a canal: Panama

public class Solution {
    public boolean isPalindrome(String s) {
        if (s.length() <= 1) return true;
        
        String str = s.replaceAll("[\\W]+", "");
        str = str.toLowerCase();
        
        StringBuffer strBuf = new StringBuffer(str);
        String rev = strBuf.reverse().toString();
        
        return (str.equals(rev));
    }
}