Hi Radu,
the exception can have multiple causes. It would be great if you could
share some example code. In most cases the problem is the following:
public class MapFunction<IN, OUT> { ....}
new MapFunction<String, WhatEverType>();
The type WhatEverType is type erasured by Java. The type must not be
declared in the "new" call but in the functions signature (IN,OUT) to
order to be preserved. Alternatively you can pass the type manually by
using the ".returns()" method or let the function implement the
"ResultTypeQueryable" interface.
Hope that helps.
Regards,
Timo
On 08.03.2016 18:57, Radu Tudoran wrote:
Hi,
I am trying to create a custom stream source. I first build this with
generic and I run into problems regarding type extraction. I tried to
put concrete types but run into the same issue (see errors below). Can
anyone provide a solution to solve this issue.
Caused by:
_org.apache.flink.api.common.functions.InvalidTypesException_: Type of
TypeVariable 'IN' in 'class test.MySourceFunction' could not be
determined. This is most likely a type erasure problem. The type
extraction currently supports types with generic variables only in
cases where all variables in the return type can be deduced from the
input type(s).
at
org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfoWithTypeHierarchy(_TypeExtractor.java:498_)
at
org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(_TypeExtractor.java:380_)
at
org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfo(_TypeExtractor.java:346_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1152_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1107_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1089_)
... 1 more
Caused by:
_org.apache.flink.api.common.functions.InvalidTypesException_: Type of
TypeVariable 'TupleEvent2' in 'class test.MySourceFunctionTuple' could
not be determined. This is most likely a type erasure problem. The
type extraction currently supports types with generic variables only
in cases where all variables in the return type can be deduced from
the input type(s).
at
org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfoWithTypeHierarchy(_TypeExtractor.java:498_)
at
org.apache.flink.api.java.typeutils.TypeExtractor.privateCreateTypeInfo(_TypeExtractor.java:380_)
at
org.apache.flink.api.java.typeutils.TypeExtractor.createTypeInfo(_TypeExtractor.java:346_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1152_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1107_)
at
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.addSource(_StreamExecutionEnvironment.java:1089_)
... 1 more
Dr. Radu Tudoran
Research Engineer - Big Data Expert
IT R&D Division
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HUAWEI TECHNOLOGIES Duesseldorf GmbH
European Research Center
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E-mail: _radu.tudoran@huawei.com_
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