Re: loop code simplification
Well I don't know why is it suggested so as in the mail by Paul,
But as I already mentioned :
- Forwarded Message -
From: Prince Sewani princesew...@ymail.com
To: dev@ofbiz.apache.org dev@ofbiz.apache.org
Sent: Tuesday, March 20, 2012 5:46 PM
Subject: Re: loop code simplification
Well If we're talking about the 'Enhanced For loop' in Java from 1.5 onwards
Then it goes something like this, you'll only get NPE if you haven't
initialized the collection,
otherwise if you've initialized the collection and there are no values in it
then
the for loop won't execute any iteration.
For example :
import java.util.ArrayList;
class Test{
static ArrayListStringt;
public static void main(String [] args){
System.out.println(before===);
for(String k : t){
System.out.println(+k);
}
System.out.println(after===);
}
}
The above program will generate an NPE when ran and the output will be :
before===
Exception in thread main java.lang.NullPointerException
at Test.main(Test.java:11)
but if I replace the ArrayList declaration with :
static ArrayListString t = new ArrayListString();
then the output will be :
before===
after===
Hope this helps.
Regards
Prince
Java does take care of it.
Regards
Prince
From: Jacques Le Roux jacques.le.r...@les7arts.com
To: dev@ofbiz.apache.org
Sent: Tuesday, March 20, 2012 8:36 PM
Subject: Re: loop code simplification
BTW, this shows how stupid is the for loop in Java implementation. The
suggested safeList() should be handled by the compiler IMO, I
see no gains to not have it in but to get NPEs. Did I miss something?
Jacques
From: Paul Foxworthy p...@cohsoft.com.au
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
Re: loop code simplification
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
Re: loop code simplification
Well If we're talking about the 'Enhanced For loop' in Java from 1.5 onwards
Then it goes something like this, you'll only get NPE if you haven't
initialized the collection,
otherwise if you've initialized the collection and there are no values in it
then
the for loop won't execute any iteration.
For example :
import java.util.ArrayList;
class Test{
static ArrayListStringt;
public static void main(String [] args){
System.out.println(before===);
for(String k : t){
System.out.println(+k);
}
System.out.println(after===);
}
}
The above program will generate an NPE when ran and the output will be :
before===
Exception in thread main java.lang.NullPointerException
at Test.main(Test.java:11)
but if I replace the ArrayList declaration with :
static ArrayListString t = new ArrayListString();
then the output will be :
before===
after===
Hope this helps.
Regards
Prince
From: Paul Foxworthy p...@cohsoft.com.au
To: dev@ofbiz.apache.org
Sent: Tuesday, March 20, 2012 4:17 PM
Subject: Re: loop code simplification
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
Re: loop code simplification
BTW, this shows how stupid is the for loop in Java implementation. The
suggested safeList() should be handled by the compiler IMO, I
see no gains to not have it in but to get NPEs. Did I miss something?
Jacques
From: Paul Foxworthy p...@cohsoft.com.au
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
Re: loop code simplification
2012/3/20 Jacques Le Roux jacques.le.r...@les7arts.com:
BTW, this shows how stupid is the for loop in Java implementation. The
suggested safeList() should be handled by the compiler IMO, I
see no gains to not have it in but to get NPEs. Did I miss something?
Nothing. Is there an implementation of this safeList() in commons ?
I think I will keep the while as they are, and work only on those
which only have the .hasNext().
Thanks for your comments !
Jacques
From: Paul Foxworthy p...@cohsoft.com.au
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java
compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
--
Erwan de FERRIERES
Re: loop code simplification
I think it's really necessary to look at the bigger picture rather than
worrying about having a null check in place. The delegator methods that return
a List pretty much never return null, so the only time that specific list will
be null is when an EntityException is thrown. So IMO the main problem with the
methods in ContactMechWorker are that they silently (aside from logging) absorb
those exceptions and then try to carry on as if nothing went wrong.
IMO those methods should probably have a 'throws EntityException' declaration
added and then all the catch blocks and listGenericValue != null checks
removed. There is so much wrong in that class though, it could do with plenty
of other work as well.
Regards
Scott
On 21/03/2012, at 4:24 AM, Erwan de FERRIERES wrote:
2012/3/20 Jacques Le Roux jacques.le.r...@les7arts.com:
BTW, this shows how stupid is the for loop in Java implementation. The
suggested safeList() should be handled by the compiler IMO, I
see no gains to not have it in but to get NPEs. Did I miss something?
Nothing. Is there an implementation of this safeList() in commons ?
I think I will keep the while as they are, and work only on those
which only have the .hasNext().
Thanks for your comments !
Jacques
From: Paul Foxworthy p...@cohsoft.com.au
Hi Erwan,
To be sure there is no Null Pointer Exception, yes, you need to test for
null first. One possibility is to just let the NPE happen.
The discussion at
http://stackoverflow.com/questions/2250031/null-check-in-an-enhanced-for-loop
suggests
for( Object o : safe( list ) ) {
// do whatever
}
Where safe would be:
public static List safe( List other ) {
return other == null ? Collections.EMPTY_LIST : other;
}
Cleaner code. I suspect the method would be inlined by most Java
compilers.
Cheers
Paul Foxworthy
Erwan de FERRIERES-3 wrote
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this
one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
-
--
Coherent Software Australia Pty Ltd
http://www.cohsoft.com.au/
Bonsai ERP, the all-inclusive ERP system
http://www.bonsaierp.com.au/
--
View this message in context:
http://ofbiz.135035.n4.nabble.com/loop-code-simplification-tp4487741p4488324.html
Sent from the OFBiz - Dev mailing list archive at Nabble.com.
--
Erwan de FERRIERES
loop code simplification
Hi,
I'm trying to remove a lot of iterators, and use the for-each syntax,
which exists since java 1.5.
During my journey, I found a lot of double tests for a while like this one:
while (typePurposes != null typePurposes.hasNext()) {
(ContactMechWorker.java line 606)
Can it be simplified to for(GenericValue contactMechTypePurpose :
theList) ? Or should I keep it like it is ?
Regards,
--
Erwan de FERRIERES
www.nereide.biz
