programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
Marshals:
• Campbell Ritchie
• Paul Clapham
• Ron McLeod
• Bear Bibeault
• Liutauras Vilda
Sheriffs:
• Jeanne Boyarsky
• Tim Cooke
• Junilu Lacar
Saloon Keepers:
• Tim Moores
• Tim Holloway
• Stephan van Hulst
• Jj Roberts
• Carey Brown
Bartenders:
• salvin francis
• Frits Walraven
• Piet Souris

Math.round() method

Ranch Hand
Posts: 63
What is the output of following

Round f4 is -5
Round f5 is 6
Round f6 is -5
Round f7 is 5

How r the value of f6 and f7 getting calculated??

Sheriff
Posts: 11343
Math.round(double d)...

"Returns the closest long to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type long."

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Math.html

Ranch Hand
Posts: 225
I am not sure, but this could be the way you do it.
First add 0.5 to the argument and than perform a Math.floor() on it.

Here f6=-5.49
-5.49 + 0.5 = -4.99
Now, we perform a Math.floor() on -4.99 giving -5, because -5 is less than -4.

Similarly f7=5.49
5.49 + 0.5 = 5.99
Now, we perform a Math.floor() on 5.99 giving 5, because 5 is less than 6.

Math.round() returns integer closest to the argument in the case above because the arguments are of type float.
[ June 17, 2005: Message edited by: Abdulla Mamuwala ]

Ranch Hand
Posts: 961
For the SCJP exam I think it is important to recognize the next things

• double Math.floor(double a): receives a double and returns a double
• double Math.ceil(double a) : receives a double and returns a double
• int Math.round(float a): receives a float returns a integer
• long Math.round(double a): receives a double returns a long

• It is important to recognize that in the next output

Now, rouund might behave different for positive and negative numbers.

However:

Be careful with that, because that is a probable question in the exam.

Ranch Hand
Posts: 531
float f6 = -5.49f;
float f7 = 5.49f;

Rounds off to the nearest integer: -5 and 5 respectively.

Given -5.5 and 5.5 you need a rounding rule since there are two "nearest" integers. They decided to round up: -5, 6 respectively. In other words if smack dab in the middle add 0.5.

shetal bansal
Ranch Hand
Posts: 63
Thanxs a lot for the wonderful replies!!

 Don't get me started about those stupid light bulbs.