Why do we need Maven or Ant, if we already have Eclipse?

Question

I think this question is an extension of Compare to the IDE for Java,do we still need Ant?

There are answers for the question above, but I wish to know a concrete ex

Answer 1

Maven is generally used to build the plugins or jars for a particular application.

Suppose you have developed an application but you don't want to go for adding the jars needed for that application manually. In this situation Maven or Ant is very helpful. Once you have written your code just got to Run As -> Maven Build (click on Maven Build) , it will generate all the required plugins or jars and include in your application library build-path. A doubt may come like how the application will get those jars, For each application there is a xml file named as POM.xml where reference of all the jars are kept there for downloading purposes.