Null Pointer... ? I can't spot it.

Question

just to preface this, st[r].getRow()returns an int[] which I'm sure is populated as it works elsewhere
in my code. I think it might have something to do with casting to a byte because that's the line that it says
the null pointer exception is on. Is there an easy way to represent an integer with 4 bytes maybe?
        byte[] ba = null;
        int bc = 0;
        for(int r = 0; r < 10; r++){
            int[] tmp = st[r].getRow();
                for(int c = 0;c < 6; c++){
                    ba[bc] = (byte) tmp[c];
                    bc++;
                   System.out.println(ba[bc]);
        System.out.println(ba);

Answer 1

You're welcome.
then why does my IDE suggest that I initialize it to null?At compile time you can't use the variable (except to assign to) unless it has been initialised to something - however, as you've seen, initialising it to null will cause a runtime error if you try and dereference it.