question Re: Use of java generics in hadoop map reduce jobs? in Archives of Support Questions (Read Only)

Use of java generics in hadoop map reduce jobs?

mohammedibrahim — Thu, 17 Mar 2016 16:51:08 GMT

How often we use java generics in map reduce jobs.Your inputs is highly appreciated!

Re: Use of java generics in hadoop map reduce jobs?

bleonhardi — Thu, 17 Mar 2016 17:52:43 GMT

You mean the normal Java Generics?

https://en.wikipedia.org/wiki/Generics_in_Java

Like ArrayList<String>() Generics?

In that case I am pretty sure almost every MapReduce job out there uses it. MapReduce can run any Java code that can be executed by the JVM currently in HDP its Java8. So if you want to use Lambda functions you could as well. And Generics have been around forever so I would hope any well written library uses them.

Re: Use of java generics in hadoop map reduce jobs?

aervits — Thu, 17 Mar 2016 17:54:06 GMT

In 3 years of writing mapreduce code,i only needed to use generics once. That's not to say it's not useful, it's pretty powerful when you are dealing with objects that have various types. In my case it was a mapreduce program running against HBase, I would extract payload and within it, I had to figure out what was the value type.

Re: Use of java generics in hadoop map reduce jobs?

bleonhardi — Thu, 17 Mar 2016 18:29:47 GMT

Hmmm I suppose it depends how you see the question. Pretty sure everybody uses generics but you are right I haven't implemented a generic class myself in a MapReduce job before. Pretty sure a lot of libraries do it but yourself during coding. Not really. I think the reason for the question might help.