RE: [COLLECTIONS/BEANUTILS] Is there a comparator that can dynamically pick a method to call on a bean?

[Eric Pugh]

Hi all,

Attached is my first attempt at submitting a BeanComparator, along with the
test case..  However, i am running into two issues becomes of my lack of
familiarty with beans that are causing me pain.  However, in my app,
everything is working great!  My testcase is attached.

1) the test suite fails because my test object which has a getBeanValue and
setBeanValue causes the WrapDynaBean class to throw an exception that
"value" has no read method..  Yet it does, and in other uses of the
BeanComparator in my code it works great.

2) All comparisions are string comparisons..  So when I compare Bigdecimals
2, 12, and 22, the orders is 12, 2, 22!  Do I need to hand in another class
to cast the objects to?

Also, I would love to see the ComparatorUtils, I created my own one to
handle the reversing of my sorts based on the text values ASC/DESC, and
removed them from my BeanComparator.

I have also attached my LowercaseComparator..  I was sorting columns of
String data, and noticed that if I didn't lowercase them, the A versus a
differenced caused funny looking ordering.  I also set up
LowercaseComparator and BeanComparator to work as decorators (similar to
ReverseComparator).  Lastly, for the bean comparator, I am using
PropertyUtils, so if you can pass in NESTED properties!  customer.name
results in getCustomer().getName() being returned!  I would love to add
jxPath converter as I build up some more experience!

Here is some sample code:

        public static Comparator sortedBean( String sortProperty, String
sortPolarity )
                throws java.lang.IllegalArgumentException {
                Comparator c = null;
                sortPolarity = sortPolarity.toUpperCase();
                if ( !sortPolarity.equals( ASC ) && !sortPolarity.equals( DESC ) ) {
                        throw new java.lang.IllegalArgumentException( "The argument:" +
sortPolarity + " was invalid." );
                }
                if ( sortPolarity.equals( ASC ) ) {
                        c = new BeanComparator( sortProperty, new 
LowercaseComparator() );
                }
                else {
                        c = new ReverseComparator( new BeanComparator( sortProperty, 
new
LowercaseComparator() ) );

                }
                return c;
        }


Any suggestions/help would be much appreciated, and I would love to see
these added to the comparators available!

Eric

-----Original Message-----
From: Michael A. Smith [mailto:[EMAIL PROTECTED]]
Sent: Friday, June 07, 2002 3:07 PM
To: Jakarta Commons Developers List
Subject: RE: [COLLECTIONS/BEANUTILS] Is there a comparator that can
dynamically pick a method to call on a bean?


On Fri, 7 Jun 2002, Henri Yandell wrote:
> Sorry Eric, I'm not sure you got my question.
>
> BeanComparator = good, +1. I think it'd be great to commit a
> BeanComparator.
>
> The ASC/DESC bit is unnecessary I think due to ReverseComparator. This is
> an opinion though, I don't believe in ASC/DESC in Comparators. So I was
> just -1 on the Polarity part of your BeanComparator :)
>
> Morgan or Michael may want to veto that though :)

Neither of us can veto your veto.  We can try to twist your arm, but in
this case, I have no reason to: I agree with you.  The reverse
comparator can provide the complementary ascending or descending
behavior.

regards,
michael


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LowercaseComparator.java
Description: Binary data

BeanComparator.java
Description: Binary data

TestBeanComparator.java
Description: Binary data

BeanComparatorObject.java
Description: Binary data

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