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https://issues.apache.org/jira/browse/FLINK-3444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15185030#comment-15185030
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Chesnay Schepler commented on FLINK-3444:
-----------------------------------------
We could add a fromElements method that takes a TypeInformation or Class
argument in addition to the values. Should be the easiest and safest way to
solve this issue.
> env.fromElements relies on the first input element for determining the
> DataSet/DataStream type
> ----------------------------------------------------------------------------------------------
>
> Key: FLINK-3444
> URL: https://issues.apache.org/jira/browse/FLINK-3444
> Project: Flink
> Issue Type: Bug
> Components: DataSet API, DataStream API
> Affects Versions: 0.10.0, 1.0.0
> Reporter: Vasia Kalavri
>
> The {{fromElements}} method of the {{ExecutionEnvironment}} and
> {{StreamExecutionEnvironment}} determines the DataSet/DataStream type by
> extracting the type of the first input element.
> This is problematic if the first element is a subtype of another element in
> the collection.
> For example, the following
> {code}
> DataStream<Event> input = env.fromElements(new Event(1, "a"), new SubEvent(2,
> "b"));
> {code}
> succeeds, while the following
> {code}
> DataStream<Event> input = env.fromElements(new SubEvent(1, "a"), new Event(2,
> "b"));
> {code}
> fails with "java.lang.IllegalArgumentException: The elements in the
> collection are not all subclasses of SubEvent".
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