[GitHub] flink issue #5047: Code refine of WordWithCount

[greghogan <gi...@git.apache.org>]

Github user greghogan commented on the issue:

    https://github.com/apache/flink/pull/5047
  
    This change doesn't work since `WordWithCount` needs to be a POJO which requires a default or no-args constructor and non-final public attributes or getters/setters. Since the type is not a POJO the `TypeExtractor` falls back to `GenericType`, which cannot be used as a key type as noted in the error message:
    
    ~~~~
    Tests run: 2, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 3.949 sec <<< FAILURE! - in org.apache.flink.streaming.test.socket.SocketWindowWordCountITCase
    testJavaProgram(org.apache.flink.streaming.test.socket.SocketWindowWordCountITCase)  Time elapsed: 0.045 sec  <<< ERROR!
    org.apache.flink.api.common.InvalidProgramException: This type (GenericType<org.apache.flink.streaming.examples.socket.SocketWindowWordCount.WordWithCount>) cannot be used as key.
    	at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:330)
    	at org.apache.flink.streaming.api.datastream.DataStream.keyBy(DataStream.java:295)
    	at org.apache.flink.streaming.examples.socket.SocketWindowWordCount.main(SocketWindowWordCount.java:79)
    	at org.apache.flink.streaming.test.socket.SocketWindowWordCountITCase.testJavaProgram(SocketWindowWordCountITCase.java:65)
    ~~~~


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