String index out of range exception

[Avi Sridhar]

Hello All, thanks for your helpful tips.

I once again stumbled upon this index out of range exception.

int[] encodeModulo;
vob = new int[2];
String test = "Long string";// Length is 60
int q = 0;
int j = pinCode.length();
int k = shortKey.length(); // length of shortKey is 60
int s1,s2,s3;
StringBuffer cpt = new StringBuffer();
for(int i =0; i< j;i++){
   s1 = encodeModulo[(int)(test.charAt(i)];
   s2 = 2 * encodeModulo[(int) (shortKey.charAt(i%k))];
   s3 = vob[i%2];
   q = (q + s1 + s2 +s3) % test.length();
   cpt.append(longKey.substring(q,1)); // exception here
}

the exception i am getting is

[BOLD]

Exception in thread "main" java.land.StringIndexOutOfBoundsException: String index out of range: -6

[/BOLD]

any pointers will be greatly appreciated.

Thanks

[Avi Sridhar]

Originally posted by Avi Sridhar:
Hello All, thanks for your helpful tips.

I once again stumbled upon this index out of range exception.

int[] encodeModulo;
vob = new int[2];
String test = "Long string";// Length is 60
int q = 0;
int j = pinCode.length();
int k = shortKey.length(); // length of shortKey is 60
int s1,s2,s3;
StringBuffer cpt = new StringBuffer();
for(int i =0; i< j;i++){
   s1 = encodeModulo[(int)(test.charAt(i)];
   s2 = 2 * encodeModulo[(int) (shortKey.charAt(i%k))];
   s3 = vob[i%2];
   q = (q + s1 + s2 +s3) % test.length();
   cpt.append(longKey.substring(q,1)); // exception here
}

the exception i am getting is

[BOLD]

Exception in thread "main" java.land.StringIndexOutOfBoundsException: String index out of range: -6

[/BOLD]

any pointers will be greatly appreciated.

Thanks

Please note the longKey has a length of 60 too

[Campbell Ritchie]

Originally posted by Avi Sridhar:


Please note the longKey has a length of 60 too

No, it hasn't. If you write "long string" it has a length of 11; your comment about length = 60 is mistaken.
You will need to check the lengths of your keys carefully; they are probably not 60. If you are actually getting -6 then (q + s1 + s2 + s3) must be a negative amount.

[Avi Sridhar]

Originally posted by Campbell Ritchie:
No, it hasn't. If you write "long string" it has a length of 11; your comment about length = 60 is mistaken.
You will need to check the lengths of your keys carefully; they are probably not 60. If you are actually getting -6 then (q + s1 + s2 + s3) must be a negative amount.

thanks for the reply. I ment to say that "a long string" , as an example.... and that string has a length of 60. The Short and long strings both of lengths of 60 too...

[Campbell Ritchie]

In which case you might be calling substring(3, 1). You can't have the first number larger than the second number. Read this.

[Avi Sridhar]

Originally posted by Campbell Ritchie:
In which case you might be calling substring(3, 1). You can't have the first number larger than the second number. Read this.

Thanks for the information. I just happened to fix that.