Add external jar file in IDE Eclipse -- Eclipse

In this video, I will teach you how to:
add external jar file in IDE Eclipse.

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My note:

My note about the tutorial is available at Github.

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Extra info:

About jar file:
jar file is a metafile for Java package. Simply said, jar file stores all info about Java package.

You can think about jar file behaves like a linker for package, it determines which package is available to be imported.

About package:
You can think it behaves like a library in C/C++.