code: public static byte[] cat(byte[]... arrays) {
          int size = 0;
          for(byte[] a: arrays)
              if(a != null)
                  size += a.length;
          byte[] cated = new byte[size];
          int pos = 0;
          for(byte[] a: arrays) {
              if(a != null) {
                  System.arraycopy(a, 0, cated, pos, a.length);
                  pos += a.length;
              }
          }
  
          return cated;
      }
docs: Concatenate the given arrays TODO: cut and paste for every primitive type
  and Object (yay! java!)
  
  @param arrays The arrays to concatenate
  @return A concatenated array