1. float aaa= aaa/2;

you are actually making a new variable with the same name as the old. this will probably cause an error if both of the aaa's are in the same function. otherwise the first aaa will be hidden by the second aaa (local scope hides global scope). so what you should do is leave the float keyword out like this:

1. float aaa = 2;
2. println(aaa); //should print: 2
3. aaa = aaa/2.0; //float division
4. println(aaa); //should print: 1

and just incase you ar doing this a lot there is a shortcut for this:

1. aaa /= 2.0; //other short cuts are *= += -=  and ++ -- (increment and decrement by 1)