# Libraries

* These are jars that are used in other java applications.
* A Java library is Java-virtual-machine-based bytecode which encodes the classes in the library.
* A library is shared via a "jar" file (essentially just a zip file of the classes) and, once it is referenced in your classpath is available to be invoked by other classes (including from other libraries).

## Creating a library

* Using gradle
  * <https://guides.gradle.org/building-java-libraries/>
* Using maven

### deploying to a artifact repository

* Examples of artifact repository
  * mvn repository
  * jfrog artifactory

## Using a library

* Via dependency management tool ie mavan, gradle
* Downloading the jar, and adding it to the class path manually

## Monkey patching

* Not advised
* You can augment an existing class. You can add methods and attributes.
* You can modify a method of an existing class.

### Links

* <https://www.beyondjava.net/what-about-monkey-patching-is-it-as-dangerous-as-they-say>

## Design

* <https://www.oracle.com/corporate/features/library-in-java-best-practices.html>


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