Understand usage of dagger2

Question

I downloaded the Coffee sample application and bring it into my IDE. After I run mvn clean , my IDE reports compilation error as:

And it won't get fixed until I run mvn compile . Obviously the sample code refers to some class that is generated by the tool.

I am quite surprised by this design as before you get the project compiled, you won't have a project that is ready to compile (looks like), kind of like you have to eat your own egg to get born.

Question: is this the normal usage scenario of dagger2? Or did I miss something?

Answer 1

Yes. Dagger makes use of the Java Annotation Processing Tool , which hooks into the compilation process. During the annotation processing, the DaggerCoffeeApp_Coffee class is generated, after which the original and generated source code is compiled as a whole.

Needless to say, before compilation this class does not exist yet. That is why your IDE cannot find it, and marks it as an error. After running mvn compile , it can find the class.