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Posted to common-user@hadoop.apache.org by ma qiang <ma...@gmail.com> on 2008/01/15 09:19:13 UTC

about the Class of IntWritable and Text

Dear colleague,
        In the method of output.collect(key, value), I can set the
"value" as Text or IntWritable in the reduce function, but I can only
set it as IntWritable in the map function. Would you tell me why?
when I set the "value" as Text, the system output the error as follows :
java.io.IOException: Type mismatch in value from map: expected
org.apache.hadoop.io.IntWritable, recieved org.apache.hadoop.io.Text
     Thanks!


Qiang Ma
Department of Computer Science and Engineering
Fudan University
Shanghai, P. R. China
EMail: maqiang1984@gmail.com

Re: about the Class of IntWritable and Text

Posted by André Martin <ma...@andremartin.de>.

Hi Qiang,
you need to set the type additionally using: 
jobConf.setOutputKeyClass(Text.class);

Cu on the 'net,
                        Bye - bye,

                                   <<<<< André <<<< >>>> èrbnA >>>>>

ma qiang wrote:
> Dear colleague,
>         In the method of output.collect(key, value), I can set the
> "value" as Text or IntWritable in the reduce function, but I can only
> set it as IntWritable in the map function. Would you tell me why?
> when I set the "value" as Text, the system output the error as follows :
> java.io.IOException: Type mismatch in value from map: expected
> org.apache.hadoop.io.IntWritable, recieved org.apache.hadoop.io.Text
>      Thanks!
>
>
> Qiang Ma
> Department of Computer Science and Engineering
> Fudan University
> Shanghai, P. R. China
> EMail: maqiang1984@gmail.com