Is there a null value that I can put into a byte array?

Question

I have a byte[] that I'm trying to make smaller, at the moment, in order to do so, i'm writing it byte-by-byte to another byte[] called temp. Both are set to the same size, because I don't know exactly what the initial array will compress to.
For example, my method will write a single byte that will tell the decompressor to carry out the next instruction 5 times (eg aaaaa = 5a), but after the instruction, I want to set the 4 a's afterwards to an empty value so that I can then iterate through temp, finding out how long to make the output byte[] by counting how many null's there are.
Eclipse is telling me null is not possible to use, I was just wondering if there is an equivalent I can use?

Answer 1

That's an idea!
The only thing is then when I come to iterate through the byte array to write it to my output array, it throws up an error that I'm trying to compare a byte to a byte[]:
          int next = 0;
          byte[] n = new byte[0];
          for (int i = 0; i < temp.length; i++) {
               if (temp[i] != n) {
                    output[next] = temp;
                    next++;
          return output;