I've used Ant and Maven build tools before, and I like dependency management mechanism of maven which seems like gives you all you need while Ant provides lightweight building capabilities.
When should I use Ivy? It looks like extension of Ant for dependency support.
Well think of Ivy as a plugin for ant that provides the automatic dependency management capabilities to the simple Ant tool. Now the question as to when to use it totally depends on your requirements. Maven is a project management tool , dependency management is just one of the module of Maven. Maven provides many other modules and functionalities that aid in the management of a project. If your project is already running on Ant and your tired of handling the dependencies manually but you don't want the over-head of configuring the other modules of maven , then Ivy is your best solution. For ivy you just have to add an ivy.xml file to handle and download the artifacts. Maven requires a lot of other things and changes in the project before you can actually benefit from it.
Muhammad Saif Asif Mirza
OCJA(5/6) OCJP(6) OCJWCD(6)