String index out of bounds error 5???

hey, im working on a program that tests to see if a string is a palindrome or not. It has to remove all characters and spaces.
Heres the program:

Code Java:

---

import java.util.*;
 
public class PalindromeTester
{
	public static void main(String[]args)
	{
	String str,another="y";
	int left,right;
 
 
	Scanner scan=new Scanner(System.in);
 
		while(another.equalsIgnoreCase("y"))
		{
		System.out.println("enter a potential palindrome: ");
		str=scan.nextLine();
 
		str=str.replaceAll("!"," ");
		str=str.replaceAll("."," ");	
 
 
 
               right=str.length();
		left=0;
 
		while(str.charAt(left)== str.charAt(right) && left < right)
		{
 
 
 
		left++;
		right--;
 
		}
 
		System.out.println();
 
		if(left<right)
			System.out.println("That string is NOT a palindrome. ");
 
		else 
			System.out.println("That string IS a palindrome");
 
		System.out.println();
		System.out.println("Test another palindrome?(y/n)");
		another=scan.nextLine();
		}
 
	}
}

---

It compiles fine, but when i run the program i get this error:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 5
at java.lang.String.charAt(String.java:686)
at PalindromeTester.main(PalindromeTester.java:26)

What does this mean? and one other question. If i use the string.replaceAll() method, can i replace it with nothing by doing this string.replaceAll("(puntuationmarkshere),"");

It means your Array is only 5 items long, and you are attempting to access Index 5. Since Indexes start at 0, your index range is: 0-4.

thank you! i just fixed it :) im starting to understand these error messages better and better. now what about the second question?

Yes you can replace the string with ""