V0.4 Post-Submission Changes

It fixes the issues with Null-pointer exception when the file is initially not created.
Fixed some of the glitches and exception shared by the reviewer.
The file can now be run smoothly.

V0.2 Duke Second Release

Tag with A-Release
(suggest that evaluator retry running a second time (for duke.txt to be created if it doesn't work on the first try)

V0.3 Release after clean up

Did some editing after TAs review

A-jar

Second release of JAR file