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From "Thomas Neidhart (JIRA)" <>
Subject [jira] [Updated] (COLLECTIONS-530) Rejecting items on predicate failure without throwing an Exception
Date Fri, 16 Jan 2015 15:46:35 GMT


Thomas Neidhart updated COLLECTIONS-530:
    Attachment: COLLECTIONS-530.patch

Attached a patch with the following changes:

 * renamed to PredicatedCollectionBuilder
 * moved to collection package
 * added methods to create predicated bags and queues
 * renamed some methods:
 ** newXXX -> asXXX
 ** add[All]IfAccepted -> add[All]
 * added a method to retrieve the rejected elements
 * improved javadoc

> Rejecting items on predicate failure without throwing an Exception
> ------------------------------------------------------------------
>                 Key: COLLECTIONS-530
>                 URL:
>             Project: Commons Collections
>          Issue Type: Improvement
>          Components: List
>    Affects Versions: 4.0
>            Reporter: Erik
>             Fix For: 4.1
>         Attachments:, COLLECTIONS-530.patch
> The PredicatedList class doesn't allow entries that fail the predicate, but throws an
Exception on entry.
> The problem I have with this, is that it places the onus of filtering out invalid entries
on the caller.
> I typically add items in a loop. The item added is the result of a method call (which
returns null if it can't create one).
> This problem is so common for me that I have created my own FilteredList class that simply
ignores invalid entries.
> I would like the PredicatedList class to be capable of rejecting items without throwing
an exception.
> I don't mind writing the code for this, but there are a great many ways in which this
can be done.
> So I was wondering what the interface should look like.
> Separate FilteredList class.
> Works, but seems a little verbose for the purpose
> New factory method: filteredList(List<T> list, Predicate<? super T> predicate)

> Nice and simple, but doesn't allow extension; other ways of dealing with predicate failure.
> New factory method with enum: predicatedList(List<T> list, Predicate<? super
T> predicate, PredicateFailEnum action)
> More verbose to use and adds an extra class, but allows more alternative ways to deal
with predicate failure.
> One more nice thing is that it might be less confusing, 
> because choosing between predicatedList and the above filteredList might not be so obvious.
> New factory method with interface: filteredList(List<T> list, Predicate<? super
T> predicate, PredicateFailInterface action)
> Complex, but the most flexible way of dealing with predicate failure.

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