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https://issues.apache.org/jira/browse/FLINK-2557?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14709297#comment-14709297
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ASF GitHub Bot commented on FLINK-2557:
---------------------------------------
Github user zentol commented on the pull request:
https://github.com/apache/flink/pull/1045#issuecomment-134203619
InvalidTypesException (from here on abbreviated as ITE) is no longer
unchecked.
For this to work i had to make changes in surprisingly many classes so
let's break it down:
* In general, InvalidProgramExceptions are now thrown for unrecoverable
conditions, where previously an ITE would be thrown..
* TypeExtractor methods that return a TypeInformation will never throw an
ITE and instead return a MissingTypeInfo if it is allowed, otherwise an
InvalidProgramException.
* One public TypeExtractor method now throws an ITE, which is
getParameterType(). This method is heavily used in the TypeExtractor itself as
well, so i didn't see a way to fix this in a non API breaking way that doesn't
rely yet again on unchecked exceptions.
* affects hadoop-compatibility functions, which now catch them
* A few OperatorClasses catched ITE's in returns(TypeInformation ...) and
then manually created a MissingTypeInfo. This now happens in the TypeExtractor
directly.
* TypeInformation classes threw an ITE in getInfoFor(Class ...) if the
given class didn't match the TypeInformation class. These have been changed to
IllegalArgumentExceptions.
* DataSet/DataStream threw an ITE in getType() if the type was a
MissingTypeInfo, changed to InvalidProgramException.
* similiar issue in StreamExecutionEnvironment
> Manual type information via "returns" fails in DataSet API
> ----------------------------------------------------------
>
> Key: FLINK-2557
> URL: https://issues.apache.org/jira/browse/FLINK-2557
> Project: Flink
> Issue Type: Bug
> Components: Java API
> Reporter: Matthias J. Sax
> Assignee: Chesnay Schepler
>
> I changed the WordCount example as below and get an exception:
> Tokenizer is change to this (removed generics and added cast to String):
> {code:java}
> public static final class Tokenizer implements FlatMapFunction {
> public void flatMap(Object value, Collector out) {
> String[] tokens = ((String) value).toLowerCase().split("\\W+");
> for (String token : tokens) {
> if (token.length() > 0) {
> out.collect(new Tuple2<String, Integer>(token,
> 1));
> }
> }
> }
> }
> {code}
> I added call to "returns(....)" here:
> {code:java}
> DataSet<Tuple2<String, Integer>> counts =
> text.flatMap(new Tokenizer()).returns("Tuple2<String,Integer>")
> .groupBy(0).sum(1);
> {code}
> The exception is:
> {noformat}
> Exception in thread "main" java.lang.IllegalArgumentException: The types of
> the interface org.apache.flink.api.common.functions.FlatMapFunction could not
> be inferred. Support for synthetic interfaces, lambdas, and generic types is
> limited at this point.
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterType(TypeExtractor.java:686)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterTypeFromGenericType(TypeExtractor.java:710)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getParameterType(TypeExtractor.java:673)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(TypeExtractor.java:365)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getUnaryOperatorReturnType(TypeExtractor.java:279)
> at
> org.apache.flink.api.java.typeutils.TypeExtractor.getFlatMapReturnTypes(TypeExtractor.java:120)
> at org.apache.flink.api.java.DataSet.flatMap(DataSet.java:262)
> at
> org.apache.flink.examples.java.wordcount.WordCount.main(WordCount.java:69)
> {noformat}
> Fix:
> This should not immediately fail, but also only give a "MissingTypeInfo" so
> that type hints would work.
> The error message is also wrong, btw: It should state that raw types are not
> supported.
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