Android Dependency Injection with Dagger 2 and Kotlin

Learn how to use Dagger, the dependency injection framework, and Kotlin, the Android-specific programming language, to create cleaner code that requires less debugging.

Dependency injection (DI) is increasingly popular in Android. Injection reduces the amount of code required in an application, reducing debugging overhead. A DI tool like Dagger, which assumes responsibility for creating and providing dependencies of an object, can help make your code cleaner, easier to understand, and easier to test. Dagger 2, the latest version, is particularly highly regarded for its speed and compile-time safety. In this course, Blake Meike teaches Android developers to use Dagger 2 with Kotlin—the newly embraced Android programming language. Review Dagger basics, including the four major types of dependency injection: method, field, lazy, and provider injection. Learn how to use Dagger annotations to declare dependencies, satisfy them, and create reusable modules you can share across your apps. Plus, learn about multibinding and components, the new way of associating modules with injection targets in Dagger 2.

Introduction

• Improve dependency injection with Dagger
• What you should know
• Using the exercise files

1. Basics

• What is Dagger?
• Why use Dagger?
• Setting up a Dagger project

2. Essential Dagger

• Building the graph with @Inject and @Component
• Introducing Dagger
• Method and field injection
• Lazy and provider injection

3. Modules

• When Dagger can't figure it out: @Modules and @Binds
• When it's complicated: @Provides
• When types are not enough: @Named
• Multibinding: Sets
• Multibinding: Maps with simple keys
• Real-world example: Architecture components #1
• Real-world example: Architecture components #2
• Real-world example: Architecture components #3
• Multibinding: Maps with complex keys
• Real-world example: Architecture components solved

4. Components

• @Components review
• Extending the builder with @Component.Builder and @BindsInstance
• @Component dependencies
• Introducing @Subcomponents
• @Subcomponents review
• Extending the subcomponent builder

5. Scope

• Rethinking the graph
• @Singletons and @Reuseable
• Custom @Scope

Conclusion

• Next steps