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https://issues.apache.org/jira/browse/AVRO-637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12903729#action_12903729
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Scott Carey commented on AVRO-637:
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I think the type in SpecificRecord and elsewhere has to be a List<T> instead of
Collection<T> in order to guarantee ordering, and that methods like add()
actually append to the list. If someone sets a field to an arbitrary
collection, say a Set, then that gets passed on to other code that expects
add() to function like an array, there will be surprises.
I believe that at minimum, GenericDatumReader.newArray() and addToArray() need
to check for instanceof List instead of Collection, and if a non-list
Collection, create a new GenericArray from a non-list Collection.
We should be able to take in any Collection to initialize an inner List; if
there was a getter/setter style for SpecificRecord then the setter could take
Collection<T> and the getter return List<T>, but with raw public member
variables our hands are tied.
Alternatively, a simple thing to do is just change Collection to List in this
patch -- clients can always use new ArrayList(Collection c);
As much as I like this feature and think that making such changes should be
done sooner rather than later, I suspect we will be changing these APIs more in
the future and it might be less painful to batch them all up. Specifically,
I'm thinking about changes to the generated classes such as using
getters/setters to hide the internal representation of the data.
> GenericArray should implement Collection
> ----------------------------------------
>
> Key: AVRO-637
> URL: https://issues.apache.org/jira/browse/AVRO-637
> Project: Avro
> Issue Type: New Feature
> Components: java
> Reporter: Doug Cutting
> Assignee: Doug Cutting
> Fix For: 1.5.0
>
> Attachments: AVRO-637.patch, AVRO-637.patch
>
>
> It would be nice if Avro arrays were better integrated with Java collections.
> The GenericArray interface permits array element reuse, which is awkward
> with java.util.Collection. But if GenericArray implemented Collection and
> the Avro runtime permitted arbitrary Collection implementations to be passed
> for Arrays then it would simplify many applications. The runtime could still
> reuse elements if an array implemented GenericArray, so performance would not
> suffer for applications that, e.g., loop over a data file, reusing instances.
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