Interesting video from Ken Kousen on how to use Groovy to make your
Java life easier i.e. extending your Java with Groovy instead of replacing it:
http://www.infoq.com/presentations/Improve-Your-Java-with-Groovy
Here's the short blurb:
Ken Kousen demoes 10 cases when he says it’s better to use Groovy: XML (and JSON), JDBC, I/O (Files), Collections, Closures, Builders, AST Transformations, Meta-programming, Spock, and Gradle.
It's 90 minutes long, so plenty to learn...