Java MapReduce

You can compile and run a MapReduce program written in Java on our Hadoop cluster. Below is an example of how to do so. You can get the WordCount.java file from HDFS:

hdfs dfs -get /var/examples/WordCount.java

 

Then run the following:

javac -cp `hadoop classpath` WordCount.java
jar cf wc.jar WordCount*.class
hadoop jar wc.jar WordCount \
/var/examples/romeojuliet.txt /user/<your_uniqname>/wc-output

 

To view the output:

hdfs dfs -cat /user/<your_uniqname>/wc-output/part-r-00000