Dagger 2 Component.Builder

Question

I have been wondering what are the benefits of creating own @Component.Builder inside Components instead of using default ones? The documentation does not say much about them, nor I could have found any reasonable examples. Anyone could share some thoughts?

Answer 1

A few of the advantages:

• As Jeremy pointed out in the comments, you'll need an explicit interface if you want to use @BindsInstance.
• An explicit interface lets you name your Module methods arbitrarily or add per-method Javadoc to your builder methods. This might be especially handy if your Module instances are optional or if they need to be manually created.
• Some IDEs and tools don't do well with code-generated interfaces. An explicit Builder lets you define your own tool-readable interfaces and let Dagger generate the implementations later.
• An explicit interface may make it easier to mock your component builders in unit tests. This may be especially handy for subcomponent builders, which observe the same rules as component builders.