Sample and resample value for a loop

edit

I need to sample a 1x1 Mat that is converted to an int. When I make a loop like this

while (grayVal <= 100){
            Log.i("Mat Value", String.valueOf(grayVal));                
        }

grayVal never changes, I know that I need to resample grayVal and pass it back into the loop. How would I go about doing this.

edit: here is my code http://pastebin.com/4HA9H39f