Bug In Javadoc Comment in the CollectionUtils class
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Key: COLLECTIONS-379
URL: https://issues.apache.org/jira/browse/COLLECTIONS-379
Project: Commons Collections
Issue Type: Bug
Components: Collection
Affects Versions: 3.2
Environment: System independent
Reporter: SHIN HWEI TAN
I came across the following bugs in the Javadoc comments in the method below in
the CollectionUtils class:
1.
{quote}
/**
* Selects all elements from input collection which match the given
predicate
* and adds them to outputCollection.
* <p>
* If the input collection or predicate is null, there is no change to the
* output collection.
*
* @param inputCollection the collection to get the input from, may be null
* @param predicate the predicate to use, may be null
* @param *outputCollection the collection to output into, may not be null*
*/
public static void select(Collection inputCollection, Predicate predicate,
Collection outputCollection) {
{quote}
_This method will execute normally when calling select((Collection)null,
(Predicate)null, (Collection)null) but the comment clearly states that
outputCollection may not be null_
2.
{quote}
/**
* Selects all elements from inputCollection which don't match the given
predicate
* and adds them to outputCollection.
* <p>
* If the input predicate is <code>null</code>, no elements are added to
<code>outputCollection</code>.
*
* @param inputCollection the collection to get the input from, may be null
* @param predicate the predicate to use, may be null
* @param *outputCollection the collection to output into, may not be null*
*/
public static void selectRejected(Collection inputCollection, Predicate
predicate, Collection outputCollection) {
{quote}
_This method will execute normally when calling
selectRejected((Collection)null, (Predicate)null, (Collection)null) but the
comment also clearly states that outputCollection may not be null_
3.
{quote}
/**
* Transforms all elements from the inputIterator with the given
transformer
* and adds them to the outputCollection.
* <p>
* If the input iterator or transformer is null, there is no change to the
* output collection.
*
* @param inputIterator the iterator to get the input from, may be null
* @param transformer the transformer to use, may be null
* @param *outputCollection the collection to output into, may not be null*
* @return the outputCollection with the transformed input added
* @*throws NullPointerException if the output collection is null*
*/
public static Collection collect(Iterator inputIterator, final Transformer
transformer, final Collection outputCollection) {
{quote}
_This method will execute normally when calling collect((Iterator)null,
(Transformer)null, (Collection)null) but the comment clearly states that
NullPointerException will be thrown when the outputCollection is null_
4.
{quote}
/**
* Transforms all elements from inputCollection with the given transformer
* and adds them to the outputCollection.
* <p>
* If the input collection or transformer is null, there is no change to
the
* output collection.
*
* @param inputCollection the collection to get the input from, may be null
* @param transformer the transformer to use, may be null
* @*param outputCollection the collection to output into, may not be null*
* @return the outputCollection with the transformed input added
* @*throws NullPointerException if the output collection is null*
*/
public static Collection collect(Collection inputCollection, final
Transformer transformer, final Collection outputCollection) {
{quote}
_This method will execute normally when calling collect((Collection)null,
(Transformer)null, (Collection)null) but the comment clearly states that
NullPointerException will be thrown when the outputCollection is null_
The bugs in the Javadoc comments above could be confusing to the users of the
Common Collection library and they could be fixed easily by the developers..
There are a few ways to fix the:
1. Throwing the NullPointerException explicitly when the outputCollection is
null.
2. Changing the Javadoc comments to include the case where all of the
parameters are null.
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