Bruno P. Kinoshita created COLLECTIONS-604:
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Summary: 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
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 not equals.
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