This is explained in the javadoc: http://hadoop.apache.org/common/docs/r0.20.1/api/org/apache/hadoop/io/ArrayWritable.html
J-D On Fri, Jan 1, 2010 at 11:29 PM, bharath vissapragada <bhara...@students.iiit.ac.in> wrote: > Hi all , > > I am using ArrayWritable in my MR job . > > Map outputs <Text ,ArrayWritable> > > Reduce takes <Text,Iterable<ArrayWritable>> > > The moment Iam trying to use the ArrayWritable in reduce using the iterator > ..I get the following error : > > 10/01/02 18:23:41 WARN mapred.LocalJobRunner: job_local_0001 > java.lang.RuntimeException: java.lang.NoSuchMethodException: > org.apache.hadoop.io.ArrayWritable.<init>() > at > org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:81) > at > org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:62) > at > org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:40) > at > org.apache.hadoop.mapred.Task$ValuesIterator.readNextValue(Task.java:940) > at org.apache.hadoop.mapred.Task$ValuesIterator.next(Task.java:880) > at > org.apache.hadoop.mapred.ReduceTask$ReduceValuesIterator.moveToNext(ReduceTask.java:237) > at > org.apache.hadoop.mapred.ReduceTask$ReduceValuesIterator.next(ReduceTask.java:233) > at HashJoin.MR_hash$redu.reduce(MR_hash.java:132) > at mtr.MyTableReduce.reduce(MyTableReduce.java:1) > at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:436) > at > org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:170) > Caused by: java.lang.NoSuchMethodException: > org.apache.hadoop.io.ArrayWritable.<init>() > at java.lang.Class.getConstructor0(Class.java:2723) > at java.lang.Class.getDeclaredConstructor(Class.java:2002) > at > org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:75) > ... 10 more > java.io.IOException: Job failed! > at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1232) > at HashJoin.MR_hash.run(MR_hash.java:294) > at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65) > at HashJoin.MR_hash.join(MR_hash.java:320) > at HashJoin.MR_hash.main(MR_hash.java:338) > > > Can Anyone tell me what the error is ?? >
