What are the functionalities of Groovy in Java?

Using Groovy language in Java can provide numerous advantages and features, including but not limited to:

1. More concise syntax: Groovy syntax is simpler and easier to understand, which can reduce the amount of code and improve code readability.
2. Dynamic typing: Groovy is a dynamic language that allows variables to change type at runtime, making code more flexible.
3. Closures: Groovy supports closures, making functional programming easier to use.
4. Optional static type checking: Groovy supports optional static type checking, which can help discover potential errors at compile time.
5. Enhanced collection operations: Groovy offers a greater variety of collection operation methods, making it more convenient to work with collections.
6. Users can directly invoke Java code in Groovy, seamlessly integrating with Java code.
7. Script Programming: Groovy can be used as a scripting language, making it easier to handle certain simple tasks.
8. AST transformation: Groovy offers AST transformation capability, which allows for code transformation and enhancement by modifying the AST.

In general, using Groovy can make Java code cleaner, more flexible, and easier to read, thus improving development efficiency and code quality.