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Time for action – building a JAR file
Before we run our job in Hadoop, we must collect the required class files into a single JAR file that we will submit to the system.
Create a JAR file from the generated class files.
$ jar cvf wc1.jar WordCount1*class
What just happened?
We must always package our class files into a JAR file before submitting to Hadoop, be it local or on Elastic MapReduce.
Tip
Be careful with the JAR command and file paths. If you include in a JAR file class the files from a subdirectory, the class may not be stored with the path you expect. This is especially common when using a catch-all classes directory where all source data gets compiled. It may be useful to write a script to change into the directory, convert the required files into JAR files, and move the JAR files to the required location.