For those new to both Java and Groovy

If you don't already know Java, these pages are for you:

3 pages on Groovy Math explain, in depth, the facilities available from both Groovy and Java:

Blocks, Closures, and Functions explains the syntax of blocks, closures, and functions.

Java Reflection in Groovy explains how to examine and manipulate objects and their fields and methods when their names aren't known at compile time.