Groovy - An agile dynamic language for the Java Platform
(JavaDoc for Java classes)

Groovy...
  • is an agile and dynamic language for the Java Virtual Machine
  • builds upon the strengths of Java but has additional power features inspired by languages like Python, Ruby and Smalltalk
  • makes modern programming features available to Java developers with almost-zero learning curve
  • supports Domain-Specific Languages and other compact syntax so your code becomes easy to read and maintain
  • makes writing shell and build scripts easy with its powerful processing primitives, OO abilities and an Ant DSL
  • increases developer productivity by reducing scaffolding code when developing web, GUI, database or console applications
  • simplifies testing by supporting unit testing and mocking out-of-the-box
  • seamlessly integrates with all existing Java objects and libraries
  • compiles straight to Java bytecode so you can use it anywhere you can use Java
Packages 
Package Description
groovy.mock.interceptor  
groovy.test  
groovy.transform  
groovy.util  
org.apache.groovy.test  
org.apache.groovy.test.transform  
org.codehaus.groovy.runtime