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https://issues.apache.org/jira/browse/FLINK-4977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Stephan Ewen closed FLINK-4977.
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> Enum serialization does not work in all cases
> ---------------------------------------------
>
> Key: FLINK-4977
> URL: https://issues.apache.org/jira/browse/FLINK-4977
> Project: Flink
> Issue Type: Bug
> Affects Versions: 1.1.3
> Environment: Java SE 1.8.0_91
> Ubuntu 14.04.4 LTS (trusty)
> Reporter: Sean Winard
> Assignee: Stephan Ewen
> Priority: Minor
> Fix For: 1.2.0, 1.1.4
>
>
> Enums produce serialization failures whether they are by themselves or part
> of a POJO in the stream. I've tried running in IntelliJ IDEA and also via
> {{flink run}}. Here is a small program to reproduce:
> {code:java}
> package org.apache.flink.testenum;
> import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
> public class TestEnumStream {
> private enum MyEnum {
> NONE, SOMETHING, EVERYTHING
> }
> public static void main(String[] args) throws Exception {
> final StreamExecutionEnvironment environment =
> StreamExecutionEnvironment.getExecutionEnvironment();
> environment.setParallelism(1);
> environment.fromElements(MyEnum.NONE, MyEnum.SOMETHING,
> MyEnum.EVERYTHING)
> .addSink(x -> System.err.println(x));
> environment.execute("TestEnumStream");
> }
> }
> {code}
> {noformat}
> Exception in thread "main" java.lang.RuntimeException: Cannot access the
> constants of the enum org.apache.flink.testenum.TestEnumStream$MyEnum
> at
> org.apache.flink.api.common.typeutils.base.EnumSerializer.createValues(EnumSerializer.java:132)
> at
> org.apache.flink.api.common.typeutils.base.EnumSerializer.<init>(EnumSerializer.java:43)
> at
> org.apache.flink.api.java.typeutils.EnumTypeInfo.createSerializer(EnumTypeInfo.java:101)
> at
> org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.fromCollection(StreamExecutionEnvironment.java:773)
> at
> org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.fromElements(StreamExecutionEnvironment.java:674)
> {noformat}
> I took a look at that line in EnumSerializer.java and swapped out the
> reflection on the "values" method for the simpler
> `enumClass.getEnumConstants()`, and that seems to work after I install my
> custom flink-core jar. I believe this is because
> [http://docs.oracle.com/javase/tutorial/reflect/special/enumMembers.html]
> specifically states you cannot reflect on the "values" method since it is
> implicitly generated at compile time.
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