Setting parameter in MapReduce Job configuration

Question

Is there any way to set a parameter in job configuration from Mapper and is accessible from Reducer.

I tried the below code

In Mapp

Answer 1

If you are using the new API your code should ideally work. Have you created this "Sum" property at the start of the job creation? For example like this

Configuration conf = new Configuration();
conf.set("Sum", "0");
Job job = new Job(conf);

If not you better use

context.getConfiguration().setIfUnset("Sum","100");

In your mapper class to fix the issue. This is the only thing I can see.