如何在Android库中创建图层而不将内部类暴露给库的使用者

Question

I'm creating an android library and wanted to organize with layers it something like this.

PublicClassExposedToLibraryConsumer.java
logic.PublicFooLogicInterface1.java
logic.PackagePrivateFooLogicClass1.java
logic.PublicFooLogicInterface2.java
logic.PackagePrivateFooLogicClass2.java
domain.PublicFooDomainInterface1.java
domain.PackagePrivateFooDomainClass1.java
domain.PublicFooDomainInterface2.java
domain.PackagePrivateFooDomainClass2.java
repository.PublicFooRepoInterface1.java
repository.PackagePrivateFooRepoClass1.java
repository.PublicFooRepoInterface2.java
repository.PackagePrivateFooRepoClass2.java

1) I want a number of layers and I want to limit interaction between those layers by using interfaces.

2) I want to only expose PublicClassExposedToLibraryConsumer.java to the consumer of the library. They should not be able to access the other classes and interfaces.

Is this possible? From what I've read in order to make something accessible to something consuming the library it needs to be public and to hide something from the consumer of the library it needs to be not public. By my reading this means that you can't separate layers without exposing something and you can't hide internal classes without being forced to use a completely flat architecture. I find this very hard to believe, I have to be missing something.

Answer 1

You can try with annotations providing specific scope for your desired file to restrict to end-user of your library . Best way to do this in Android is using @RestrictTo support library annotation on class level .

Note : For Fields and Methods of particular entity can be scoped with access-modifiers like private, protected or package-protected etc. *(Just ignore if you already know that)

@RestrictTo : Denotes that the annotated element should only be accessed from within a specific scope (as defined by RestrictTo.Scope ).