[jira] [Commented] (COLLECTIONS-604) More uniform safe-null methods in CollectionUtils

["Jonas Holtkamp (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/COLLECTIONS-604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16037292#comment-16037292 ] 

Jonas Holtkamp commented on COLLECTIONS-604:
--------------------------------------------

As [~britter] writes on the Mailing List:
{quote}Nobody seems to have an opinion on this issue so you should start implementing your preference.{quote}
Should we design an approach together or what is your favourite way of implementing this here?

> More uniform safe-null methods in CollectionUtils
> -------------------------------------------------
>
>                 Key: COLLECTIONS-604
>                 URL: https://issues.apache.org/jira/browse/COLLECTIONS-604
>             Project: Commons Collections
>          Issue Type: Bug
>          Components: Collection
>    Affects Versions: 4.1
>            Reporter: Bruno P. Kinoshita
>            Assignee: Bruno P. Kinoshita
>            Priority: Minor
>         Attachments: COLLECTIONS-604.csv
>
>
> Currently, there are 65 public methods in `CollectionUtils`. And 53 without the deprecated ones. Out of these, 24 handle `null` arguments. The remaining methods throw a `NullPointerException` (NPE) at some part of its code.
> The methods that handle nulls, throw NPE, or return empty columns, boolean values, or just doesn't do anything.
> As a user of the API, I would expect a more uniform behaviour across the methods of `CollectionUtils`. COLLECTIONS-600 address one of these methods.
> `removeAll` (2x) and `retainAll` (2x) both state that a NPE will be thrown if either parameter is `null`. However, they never check if the values are null, and instead allow the code to run until a NPE is thrown.
> And the following code shows that `isEmpty` and `isFull` behave differently too.
> {code:java}
> Collection<String> c = null;
> System.out.println(CollectionUtils.isEmpty(c)); // return true
> System.out.println(CollectionUtils.isFull(c));  // throws a NPE
> {code}
> If I don't have to worry about `null`s with `#isEmpty`, I would expect the same from its related-method `#isFull`.
> What would be a good approach for it? Define a behaviour to all methods? Or leave as is, but add more documentation?
> There are a few methods that can easily be updated to check for `null` values. Others would require a bit more thinking. An example if the method in question for COLLECTIONS-600. It checks equality of collections, and when both collections are `null`, it says that they are equals. Google Guava [Iterables#elementsEqual|https://github.com/google/guava/blob/312aeb938bd35b5b7c8930e19ff5d1ca38e49424/guava/src/com/google/common/collect/Iterables.java#L232] and [Iterators#elementsEqual|https://github.com/google/guava/blob/312aeb938bd35b5b7c8930e19ff5d1ca38e49424/guava/src/com/google/common/collect/Iterators.java#L274] do not check for null values, for what it is worth.



--
This message was sent by Atlassian JIRA
(v6.3.15#6346)