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From Timo Walther <twal...@apache.org>
Subject Re: Applying an void function to DataStream
Date Thu, 19 Apr 2018 13:36:29 GMT
In your case a FlatMapFunction is better suited because it allows 0, 1 
or more output.

It would look like this:

text.flatMap((FlatMapFunction<String, Void>) (value, out) ->parse(value));


Or with an anonymous class:

text.flatMap(new FlatMapFunction<String, Void>() {
    @Override public void flatMap(String value, Collector<Void> out)throws Exception
{
       parse(value); }
});


Regards,
Timo

Am 19.04.18 um 15:26 schrieb Soheil Pourbafrani:
> parse function is a static function from another class I've imported 
> into the project.
>
> On Thu, Apr 19, 2018 at 5:55 PM, Soheil Pourbafrani 
> <soheil.ir08@gmail.com <mailto:soheil.ir08@gmail.com>> wrote:
>
>     Thanks,
>     my map code is like this:
>
>     stream.map(x -> parse(x));
>
>     I can't get what you mean!
>     Something like the line below?
>
>     DataStream<java.lang.void> t = stream.map(x -> parse(x));
>
>     ?
>
>     On Thu, Apr 19, 2018 at 5:49 PM, Timo Walther <twalthr@apache.org
>     <mailto:twalthr@apache.org>> wrote:
>
>         Hi Soheil,
>
>         Flink supports the type "java.lang.Void" which you can use in
>         this case.
>
>         Regards,
>         Timo
>
>
>         Am 19.04.18 um 15:16 schrieb Soheil Pourbafrani:
>
>             Hi, I have a void function that takes a String, parse it
>             and write it into Cassandra (Using pure java, not Flink
>             Cassandra connector). Using Apache Flink Kafka connector,
>             I've got some data into DataStream<String>. Now I want to
>             apply Parse function to each message in
>             DataStream<String>, but as the Parse function returns
>             nothing (is void), I got the error
>             no instance of type variable R exists so that void
>             conforms to R
>
>             Is there any way to do such process using apache Flink?
>
>
>
>
>


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