final member

Does declaring a class member as final cause it to take less memory or cause any processing using it to be faster?
same for final methods or classes?
LVL 1
allelopathAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

ksivananthCommented:
I don't think, final is nothing to do with memory/speed!
ksivananthCommented:
*nothing - anything
mccarlIT Business Systems Analyst / Software DeveloperCommented:
The differences are probably very small, but yes there could be performance improvements. Any extra information you give the compiler, gives it a chance to optimize the bytecode more aggressively.

Essentially, because of this, but more importantly to help reduce bugs, you should use final everywhere where it is appropriate, it just gives the compiler more info and therefore more of a chance to pick up errors and to optimize.
Learn Ruby Fundamentals

This course will introduce you to Ruby, as well as teach you about classes, methods, variables, data structures, loops, enumerable methods, and finishing touches.

Kyle AbrahamsSenior .Net DeveloperCommented:
It doesn't unless you are multithreading (making it visible to all threads, assigning only once) and for clearer design.

http://stackoverflow.com/questions/4279420/does-use-of-final-keyword-in-java-improve-the-performance
gudii9Commented:
Check following interesting explanation, link

Use private and static methods, and final classes, to encourage inlining by the compiler.

http://www.javaperformancetuning.com/tips/rawtips.shtml
dpearsonCommented:
For multi threaded code using final makes a huge difference in performance.  This isn't because of anything that's happening to the variable, it's because you don't need to lock the threads before you access the variable:

public class SlowClass {
    private int m_Value ;

    public synchronized int getValue() { return m_Value ; }
    public synchronized void setValue(int n) { m_Value = n ; }
}

public class FastClass {
    private final int m_Value ;

    public FastClass(int n) {
        m_Value = n ;
    }

    public int getValue() { return m_Value ; } // NOTE: Not synchronized
}

In a multi threaded situation SlowClass may run 100x slower than FastClass because there's no requirement to lock on the class before accessing the data.

This is when final really makes a difference.

It can also help the compiler produce slightly more optimized code (when applied to the class or member level) but those won't get you order of magnitude benefits, as the multi threading final will.

Doug
ksivananthCommented:
>>For multi threaded code using final makes a huge difference in performance

the diff is between sync/non-sync code, nothing to do with final.
dpearsonCommented:
>> the diff is between sync/non-sync code, nothing to do with final.

OK - technically correct it's not the "final" keyword that makes the performance difference, it's the different coding pattern that the use of final produces (i.e. immutable objects) which in turn generates the huge performance difference.

Doug

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Java

From novice to tech pro — start learning today.