This week's book giveaway is in the Android forum. We're giving away four copies of Head First Android and have Dawn & David Griffiths on-line! See this thread for details.

this following question is from mock exam by RHE what is the value of the follwing expression ? MAth.round(Math.random()+2.50001); options are :- A. 2 B. 3 C. It is impossible to say the answer is b ie. ->3 my question is that when Math.random() method generate a random no. say 0.99999 on addition with 2.50001 it becomes 3.50 and after rounding the result will give 4 which is not in the option list . so what is the right answer please tell me the right answer thanks in advn. sunil

Hi, You are right: the expression could be evaluated to 3 or 4. The answer b (i.e. 3) is wrong. Try this two or three times:

public class Z { public static void main(String[] args) { int j = 0; for (int i = 0; i < 10000;i++) { j = (int)Math.round(Math.random() + 2.50001); if (j != 3) System.out.println("i = " + i + " j = " + j); } } }

Mihai T.

[This message has been edited by Mihai T (edited June 25, 2001).]

Hi Sunil, sandip & Mihai, The result is just because of Math.round. Math.round method always casts to either int or long and returns. What JLS says about Math.round : The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type int. In other words, the result is equal to the value of the expression: (int)Math.floor(a + 0.5f) or (long)Math.floor(a + 0.5d) Hope this helps. Thanks and regards V.Srinivasan

Hi Sunil, As you have mentioned, the book answer is incorrect. The correct answer is C. It has been corrected in other printings. When you buy a book, always look for the Errata on-line because all books have errors! Find the errata here for RHE book. Errata for Complete Javaï¿½ 2 Certification Study Guide Regards, Manfred.