MapReduce cannot be resolved to a type error

Question

I am getting an error in my map reduce program:

IntWritable cannot be resolved to a type, LongWritable cannot beresolved to a type 
Configuration cannot be resolved to a type, Job cannot be resolved to a type, etc. 

Please let me know what could be the possible error?

Answer 1

One of the reasons could be different serialized datatypes used in generic mapper/reducer output key/values and actual mapper/reducer output key/values. Hard to tell without looking at the code. Please share the code so that we can know the exact reason.