Type mismatch in key from map: expected org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.LongWritable

Question

I am trying to run a map/reducer in java. Below are my files

WordCount.java

package counter;


public class          


        

Answer 1

I got a similar exception stack trace due to improper Mapper Class set in my code (typo :) )

job.setMapperClass(Mapper.class)  // Set to org.apache.hadoop.mapreduce.Mapper due to type

Notice that mistakenly I was using Mapper class from mapreduce package, I changed it to my custom mapper class:

job.setMapperClass(LogProcMapperClass.class) // LogProcMapperClass is my custom mapper.

The exception is resolved after I corrected the mapper class.