14/12/2001 11:15:31, Sujit <[EMAIL PROTECTED]> wrote:
>String a = "aa";
>
>the String object "a" is not created
>that goes into the literal pool of the class ...
>
>btw
>array.length is a property not a method
Indeed it is. You are right. The array.length is a property. The length property
adjusts itself everytime a new element is inserted in the array.
>probably array.length also doesn't do any calculation.
No more that the
int l = arraStr.length;
for (int j=0; j<ll; j++)
is doing. The only thing they are doing then is to read the values from the memory.
One is reading the value l and the other the value from the property length. Therefore
I would expect more or less the same assignm,ent times for the a +=
"aa"; but the second one always seems to be slower.
>still I'm not convinced with my reasoning,
>can anyone else help us out.
>
>
>----- Original Message -----
>From: "Panagiotis Konstantinidis" <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>Sent: Friday, December 14, 2001 6:04 AM
>Subject: Re: OffBeat question...Java performance.
>
>
>> Hmmm.. Using jdk1.4 under windows 2000 I got the error message:
>>
>> not a statement: String a = "aa";
>>
>> Declarign a String a; and changing the String a = "aa"; to a += "aa"; it
>worked but, despite my predictions, the first chunk of code run faster than
>the second! I would expect the second to be faster... After running the
>program twice doing a
>> += "aa", the first loop yielded 45396 and 45075 respectively while the
>second loop yeilded 46486 and 45255.
>>
>> Weird. Since the first loop has the overhead of recalculating the arary
>length (even if it is a minimum overhead calculation) I would expect
>different results...
>>
>> 14/12/2001 10:58:23, ShriKant Vashishtha <[EMAIL PROTECTED]>
>wrote:
>>
>> >Hi,
>> >
>> >This is the actual code which I tested. I am using the IBM WebSphere3.53
>> >JIT
>> >enabled compiler. In my view also the second code should have been
>faster.
>> >But
>> >it's the first code instead which is puzzling me.
>> >
>> >-ShriKant
>> >
>> >
>> >
>> >A mailing list about Java Server Pages specification and reference wrote:
>> >
>> >> From: Sujit <[EMAIL PROTECTED]>@JAVA.SUN.COM on 12/14/2001 05:35 AM
>EST
>> >>
>> >> Please respond to A mailing list about Java Server Pages specification
>> >and
>> >> reference <[EMAIL PROTECTED]>
>> >>
>> >> To: [EMAIL PROTECTED]
>> >> cc:
>> >> Subject: Re: OffBeat question...Java performance.
>> >>
>> >> Is this the actual code you tested and got the output ...
>> >> or
>> >> instead of the line String a = "aa";
>> >> you had some other code ??
>> >>
>> >> actually, String a = "aa"; even if you loop does nothing ...
>> >>
>> >> I think both the for loop will not be executed at all ...
>> >>
>> >> the JVM should optimises the code ...
>> >> and the time should be same ...
>> >>
>> >> BTW your second code snippet should be faster than the first one ...
>> >>
>> >> ----- Original Message -----
>> >> From: "ShriKant Vashishtha" <[EMAIL PROTECTED]>
>> >> To: <[EMAIL PROTECTED]>
>> >> Sent: Friday, December 14, 2001 5:14 AM
>> >> Subject: Re: OffBeat question...Java performance.
>> >>
>> >> > Hi,
>> >> >
>> >> > I apologise for the mistake. You are right. Please find the currect
>> >> > snippets.
>> >> >
>> >> > String [] arrayStr = new String[20000];
>> >> > System.out.println(System.currentTimeMillis());
>> >> > for(i=0;i<arrayStr.length;i++){
>> >> > String a="aa";
>> >> > }
>> >> > System.out.println(System.currentTimeMillis());
>> >> >
>> >> > Output:
>> >> > 1008319728796
>> >> > 1008319728799
>> >> >
>> >> > String [] arrayStr = new String[20000];
>> >> > int length = arrayStr.length;
>> >> > System.out.println(System.currentTimeMillis());
>> >> > for(i=0;i<length;i++){
>> >> > String a="aa";
>> >> > }
>> >> > System.out.println(System.currentTimeMillis());
>> >> >
>> >> > Output:
>> >> > 1008319767200
>> >> > 1008319767221
>> >> >
>> >> > Regards,
>> >> > -ShriKant
>> >> >
>> >> > A mailing list about Java Server Pages specification and reference
>> >wrote:
>> >> >
>> >> > > From: Sujit <[EMAIL PROTECTED]>@JAVA.SUN.COM on 12/14/2001 04:51
>AM
>> >> EST
>> >> > >
>> >> > > Please respond to A mailing list about Java Server Pages
>> >specification
>> >> > and
>> >> > > reference <[EMAIL PROTECTED]>
>> >> > >
>> >> > > To: [EMAIL PROTECTED]
>> >> > > cc:
>> >> > > Subject: Re: OffBeat question...Java performance.
>> >> > >
>> >> > > what is the difference between both the code ..
>> >> > >
>> >> > > I don't see any difference between the code
>> >> > > that is embedded between the system.out's
>> >> > >
>> >> > > am I missing something ??
>> >> > >
>> >> > > ----- Original Message -----
>> >> > > From: "ShriKant Vashishtha" <[EMAIL PROTECTED]>
>> >> > > To: <[EMAIL PROTECTED]>
>> >> > > Sent: Friday, December 14, 2001 4:34 AM
>> >> > > Subject: OffBeat question...Java performance.
>> >> > >
>> >> > > > Hi,
>> >> > > >
>> >> > > > I am trying to judge the performance impact of the following Java
>> >> code.
>> >> > > >
>> >> > > > String [] arrayStr = new String[20000];
>> >> > > > System.out.println(System.currentTimeMillis());
>> >> > > > for(i=0;i<arrayStr.length;i++){
>> >> > > > String a="aa";
>> >> > > > }
>> >> > > > System.out.println(System.currentTimeMillis());
>> >> > > >
>> >> > > > Output:
>> >> > > > 1008319728796
>> >> > > > 1008319728799
>> >> > > >
>> >> > > > String [] arrayStr = new String[20000];
>> >> > > > int length = arrayStr.length;
>> >> > > > System.out.println(System.currentTimeMillis());
>> >> > > > for(i=0;i<arrayStr.length;i++){
>> >> > > > String a="aa";
>> >> > > > }
>> >> > > > System.out.println(System.currentTimeMillis());
>> >> > > >
>> >> > > > Output:
>> >> > > > 1008319767200
>> >> > > > 1008319767221
>> >> > > >
>> >> > > > In my view the first code stub should have been faster as in the
>> >> second
>> >> > > > snippet we are getting an overhead of a instance variable call
>over
>> >> an
>> >> > > > String [] object compared to the length already computed in the
>> >first
>> >> > > > one. What is happening behind the scene, I am not aware. Could
>> >> somebody
>> >> > > > please explain.
>> >> > > >
>> >> > > > Thanks,
>> >> > > > -ShriKant
>> >> > > >
>> >> > > >
>> >> > >
>> >> >
>> >>
>>
>>===========================================================================
>> >> > > > To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>> >> > > JSP-INTEREST".
>> >> > > > For digest: mailto [EMAIL PROTECTED] with body: "set
>> >JSP-INTEREST
>> >> > > DIGEST".
>> >> > > > Some relevant FAQs on JSP/Servlets can be found at:
>> >> > > >
>> >> > > > http://archives.java.sun.com/jsp-interest.html
>> >> > > > http://java.sun.com/products/jsp/faq.html
>> >> > > > http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> >> > > > http://www.jguru.com/faq/index.jsp
>> >> > > > http://www.jspinsider.com
>> >> > > >
>> >> > >
>> >> > >
>> >> >
>> >>
>>
>>===========================================================================
>> >> > > To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>> >> > > JSP-INTEREST".
>> >> > > For digest: mailto [EMAIL PROTECTED] with body: "set
>JSP-INTEREST
>> >> > > DIGEST".
>> >> > > Some relevant FAQs on JSP/Servlets can be found at:
>> >> > >
>> >> > > http://archives.java.sun.com/jsp-interest.html
>> >> > > http://java.sun.com/products/jsp/faq.html
>> >> > > http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> >> > > http://www.jguru.com/faq/index.jsp
>> >> > > http://www.jspinsider.com
>> >> >
>> >> >
>> >>
>>
>>===========================================================================
>> >> > To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>> >> JSP-INTEREST".
>> >> > For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST
>> >> DIGEST".
>> >> > Some relevant FAQs on JSP/Servlets can be found at:
>> >> >
>> >> > http://archives.java.sun.com/jsp-interest.html
>> >> > http://java.sun.com/products/jsp/faq.html
>> >> > http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> >> > http://www.jguru.com/faq/index.jsp
>> >> > http://www.jspinsider.com
>> >> >
>> >>
>> >>
>>
>>===========================================================================
>> >> To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>> >> JSP-INTEREST".
>> >> For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST
>> >> DIGEST".
>> >> Some relevant FAQs on JSP/Servlets can be found at:
>> >>
>> >> http://archives.java.sun.com/jsp-interest.html
>> >> http://java.sun.com/products/jsp/faq.html
>> >> http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> >> http://www.jguru.com/faq/index.jsp
>> >> http://www.jspinsider.com
>> >
>>
>>===========================================================================
>> >To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>JSP-INTEREST".
>> >For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST
>DIGEST".
>> >Some relevant FAQs on JSP/Servlets can be found at:
>> >
>> > http://archives.java.sun.com/jsp-interest.html
>> > http://java.sun.com/products/jsp/faq.html
>> > http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> > http://www.jguru.com/faq/index.jsp
>> > http://www.jspinsider.com
>> >
>> __________________________________________
>> "It can only be attributed to human error"
>> 2001 A Space Odyssey
>>
>>
>===========================================================================
>> To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff
>JSP-INTEREST".
>> For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST
>DIGEST".
>> Some relevant FAQs on JSP/Servlets can be found at:
>>
>> http://archives.java.sun.com/jsp-interest.html
>> http://java.sun.com/products/jsp/faq.html
>> http://www.esperanto.org.nz/jsp/jspfaq.jsp
>> http://www.jguru.com/faq/index.jsp
>> http://www.jspinsider.com
>>
>
>===========================================================================
>To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST".
>For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST".
>Some relevant FAQs on JSP/Servlets can be found at:
>
> http://archives.java.sun.com/jsp-interest.html
> http://java.sun.com/products/jsp/faq.html
> http://www.esperanto.org.nz/jsp/jspfaq.jsp
> http://www.jguru.com/faq/index.jsp
> http://www.jspinsider.com
>
__________________________________________
"It can only be attributed to human error"
2001 A Space Odyssey
===========================================================================
To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST".
For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST".
Some relevant FAQs on JSP/Servlets can be found at:
http://archives.java.sun.com/jsp-interest.html
http://java.sun.com/products/jsp/faq.html
http://www.esperanto.org.nz/jsp/jspfaq.jsp
http://www.jguru.com/faq/index.jsp
http://www.jspinsider.com
