Coding challenge 1: Build Your Own wc Tool

from https://codingchallenges.fyi/challenges/challenge-wc/

Starting the coding challenges with things that are already in my wheelhouse, Java with Maven. The idea is to grow out of my comfort zone a bit with each challenge.

Install and run

Build

We are using Apache Maven to build and package our project. You can install using the instructions on the installation page, but I highly recommend using SDKMAN! to manage your JDKs and Tools. After you have Maven installed, go to the project folder (WcTool) and run:

mvn clean install

This will compile the project, run the unit tests, and package everything in a jar file. This process only needs to be done once, unless you make any changes to the code. After this a target/WcTool.jar file should have been created.

Config

Instead of running the jar we have just created, we will use the ccwc script as required in the challenge description. To make sure we are able to run it, execute the following command:

chmod -x ccwc

This also needs to be done only once. We could add this to $PATH to make the command usable from any directory, but that's outside our current scope.

Run

Run on a test file

Run the following commands in a terminal to check its functionality:

• Without any flags:

./ccwc src/test/resources/test.txt
  7145    58164   342190  src/test/resources/test.txt

• Using flags for specific counts

./ccwc -l src/test/resources/test.txt
  7145 src/test/resources/test.txt

• Reading from stdin:

cat src/test/resources/test.txt | ./ccwc -w
  58164

Final remark

This was a fun challenge, and I was happy to write it only using the Standard Java Libraries, but parsing varargs can be a pain, and unless you're learning/practicing, I recommend using Picocli when you need to turn Java code into a CLI.