Help with a simple encryption program?

[googleplexx]

Hello,

I'm trying to make a simple Caesar cipher however instead of A-Z i want to also include 0-9. where 9 wraps back to A.

The best i could can do shift letters and integers independently so a string like "TESTING SHIFT Z 9" with a key of 1
becomes
"UFTUJOH TIJGU A 0"

9 wraps to 0 and Z wraps to A

here is how I did that:

    private char encryptChar(char c, int k) {
    	if (Character.isDigit(c))
    		return (char) ('0' + (c - '0' + k) % 10); //handles the ints
    	else if (Character.isLetter(c))
    		return (char) ('A' + (c - 'A' + k) % 26); //handles the letters
    	else
    		return c;
    }

Is there a way I can make 9 wrap around to A such that instead of the traditional?

so that instead of:
ABCDEFGHIJKLMNO PQRSTUVXYZ (Z wraps to A)

what i'm trying to do is:
ABCDEFGHIJKLMNO PQRSTUVXYZ01234 65789 (9 wraps to A)

Thanks in advance for any help!

[jkmyoung]

Change the mod to 36 for both, and adjust the final result accordingly. Here's how to work the digits:

        char d;
        if (Character.isDigit(c)) {
            d = (char) ((c - '0' + k) % 36);
            if (d <= 9)
              return '0' + d;
            else
              return d - 10 + 'A';
         }

You may need to cast where appropriate.