Google Guice is a lightweight Java dependency injection framework. Guice takes the pain out of writing and maintaining Java applications big and small. Guice has gained a great deal of traction both inside and outside of Google. Almost every Java-based application at Google is also a Guice-based application; the list includes AdWords, Google Docs, Gmail, and even YouTube. Open source users run Guice in everything from file-sharing software to ATMs. Now the team released Google Guice 2.