You can initialize IntWritable with an empty constructor.
IntWritable i=new IntWritable();
On Fri, Mar 13, 2009 at 2:21 PM, Andy Sautins
<andy.saut...@returnpath.net>wrote:
>
>
> In writing a Map/Reduce job I ran across something I found a little
> strange. I have a situation where I don't need a value output from map.
> If I set the value of the value of OutputCollector<Text, IntWritable> to
> null I get the following exception:
>
>
>
> java.lang.NullPointerException
>
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:56
> 2)
>
>
>
> Looking at the code in MapTask.java ( Hadoop .19.1 ) it makes sense
> why it would throw the exception:
>
>
>
> if (value.getClass() != valClass) {
>
> throw new IOException("Type mismatch in value from map: expected
> "
>
> + valClass.getName() + ", recieved "
>
> + value.getClass().getName());
>
> }
>
>
>
> I guess my question is as follows: is it a bad idea/not normal to
> collect a null value in map? Outputting from reduce through
> TextOutputFormat with a null value as I expect. If the value is null
> only they key and newline are output.
>
>
>
> Any thoughts would be appreciated.
>
>
>
>
>
>
>
>
--
Richa Khandelwal
University Of California,
Santa Cruz.
Ph:425-241-7763
