Homework - Index out of Bounds error

import chn.util.*;
public class PalindromeLab1 
{
	public String isDouble(String f)
	{
		int length = f.length();
		System.out.println(length);
		int c = 0;
		for (int i = 0; i <= length; i++)
		{
			
			System.out.print(c);
			if (f.charAt(i) == f.charAt(length - (i+1)))
				{
				System.out.print(" ");
				c=c+1;
				System.out.print(c);
				}
			else 
				{
				System.out.print(" ");
				c=c-1;
				System.out.print(c);
				}
		}
			if (c==length)
			System.out.println("Yup. It's a palindrome, alright.");
			if (c!=length)
			System.out.println("No. It's not a palindrome. :( ");
	return (" ");
	}
}

import chn.util.*;
public class PalindromerLabThinger1 {
public static void main(String[]args)
{
	ConsoleIO console = new ConsoleIO();
	PalindromeLab1 object = new PalindromeLab1();
	System.out.print("Enter a palindrome: ");
	String palindrome1 = console.readLine();
	int length = palindrome1.length();
	String thing = object.isDouble(palindrome1);
	System.out.print(" " + thing);
}}