Executing helloworld.java in apache hadoop?

The way a jar is run in hadoop is by the command.

The way a jar is run in hadoop is by the command $HADOOP_HOME/bin/hadoop jar your_jar_file You can also use -jar to force it to run as a local job. Useful for playing and debugging. While I haven't tested with such a simple application, I think it should print the line and then be done.

Don't hold me to that though. :-P You might need to specify main throws Exception but I'm not 100% on that. My code has it.

I hope that helps. As mentioned in other answers, without getting into setting up Jobs and MapReduce, there's not going to be a gain from Hadoop.

Yes! Thats exactly what I wanted, the syntax to run it as a local job. I tried so many ways but couldnt figure it out.Thanks.

– emiljho Feb 3 at 14:00.

As far as I understand the apache hadoop is irrelevant in your case. You question is "how to run hello world written in java"? If my assumption is correct, do the following.

Install JDK compile your java code using command javac java. You have to run this from directory where your code is. The JAVA_HOME/bin should be in your path.

If #2 succeeded you should be able to see class at your working directory. Now run it by typing java world Search for any java tutorial for beginners for details. Good luck.

I know its irrelevent. But I wanna know how we run a java program through hadoop. To get started I went for a simple program.

Can you tell me then how to run java programs(simple ones) in hadoop? Thank you – emiljho Feb 2 at 14:21 Wordcount example is the helloworld of hadoop. Go through that – Harsha Hulageri Feb 24 at 7:41.

Short answer: You don't. Hadoop doesn't run java applications in the general sense. It runs Map Reduce jobs, which can be written in java, but don't have to be.

You should probably start with reading some of the apache hadoop documentation. Here's the Map Reduce tutorial. You might also want to look at Tom White's book "Hadoop: the definitive guide".

Hadoop is a batch oriented large scaled data processing system. It's really only suited to applications in that problem space. If those aren't the kind of problems you're trying to solve, Hadoop isn't what you're looking for.

– emiljho Feb 2 at 15:48 2 problem lol, no it's not meant to execute some hello world stuff. Look at wordcount and look for what kind of work you are using that. – Thomas Jungblut Feb 2 at 19:35.

You need to look at how Map Reduce works. You may want to look at the src of the hadoop examples to get a feel of how the Map Reduce programs are written.

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