java String - String index out of range , charAt
===

I try to make a program which it can find palindromic number ( it has to be pruduct of two 3-digits number and I hope that it contain 6 digit but it is not important ) 
Here is my code :

    public class palindromicNumber {
    public static void getPalindromicNumber(){
        boolean podminka = false;
        int test;
        String s;
    for(int a = 999;podminka == false && a>100; a-- ){
        for(int b = 999;podminka == false && b>100; b-- ){
         test = a*b;
         s = Integer.toString(test); 
         int c = 0;
         int d = s.length();
         while(c!=d && podminka == false){                          
                 
             if(s.charAt(c)==s.charAt(d)){  // I think that problem is here but I can't see what
                   System.out.println(s);
                   podminka = true;                                
         }
                 c++;
                 d--;
        }
        } 
    }
}

and if I want to compile it :

    Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 6
	at java.lang.String.charAt(String.java:695)
	at faktorizace.palindromicNumber.getPalindromicNumber(palindromicNumber.java:24)
	at faktorizace.Faktorizace.main(Faktorizace.java:19)
Java Result: 1

 