How Java Hadoop Mapper can send multiple values

Question

My mapper needs to send the following tuples:

And I want to send to reducer the custID as a key, and as value th

Answer 1

The simplest I can think of is just to merge them into a single string:

output.collect(custID, prodID + "," + rate);

Then, split if back up on the reducers.

If you post a little more code from your mapper maybe we could give a better example.

UPDATE: That said, you asked for the best way. The most correct way is probably to create a separate class grouping prodID and rate together and send that.