What is an uber jar?

Question

I am reading Maven documentation and came across the name \'uber-jar\'.

What does an uber-jar mean and what are its features/advantages?

Answer 1

ubar jar is also known as fat jar i.e. jar with dependencies.
There are three common methods for constructing an uber jar:

1. Unshaded: Unpack all JAR files, then repack them into a single JAR. Works with Java's default class loader. Tools maven-assembly-plugin
2. Shaded: Same as unshaded, but rename (i.e., "shade") all packages of all dependencies. Works with Java's default class loader. Avoids some (not all) dependency version clashes. Tools maven-shade-plugin
3. JAR of JARs: The final JAR file contains the other JAR files embedded within. Avoids dependency version clashes. All resource files are preserved. Tools: Eclipse JAR File Exporter

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