We learned the benefits of DI in software engineering, but choosing a framework wisely is also important when implementing DI because each framework has its own advantages and disadvantages. There are various Java-based dependency injection frameworks available in the open source community, such as Dagger, Google Guice, Spring DI, JAVA EE 8 DI, and PicoContainer.

Here, we will learn in detail about Google Guice (pronounced juice), a lightweight DI framework that helps developers to modularize applications. Guice encapsulates annotation and generics features introduced by Java 5 to make code type-safe. It enables objects to wire together and tests with fewer efforts. Annotations help you to write error-prone and reusable code.

In Guice, the new keyword is replaced with @inject for injecting dependency. It allows constructors, fields, and methods (any method with multiple numbers of arguments) level injections. Using Guice, we can define custom scopes and circular dependency, and it has features to integrate with Spring and AOP interception.

Moreover, Guice also implements Java Specification Request (JSR) 330, and uses the standard annotation provided by JSR-330. The first version of Guice was introduced by Google in 2007 and the latest version is Guice 4.1.