I just started doing dependency injection using Dagger 2. When I spun up my modules, components and tried to build my application, gradle threw the error
Error:(4, 24) error: cannot find symbol class Generated
I dug into it and found that the error is in one of the classes Dagger generates to do DI. The particular class that's missing was javax.annotation.Generated and the line throwing the error is the line that anntotates a Dagger generated class as @Generated("dagger.internal.codegen.ComponentProcessor")
This question helped in finding the solution which is to add the javax package as a dependency by adding the line compile 'org.glassfish:javax.annotation:10.0-b28' to my gradle build file. This led to a successful build.
My question is, why is that not added as a transitive dependency for Dagger or why hasn't anyone else faced this particular issue (I assume so, since I couldn't find any question here regarding this?
Read this for more info: https://github.com/google/dagger/issues/95
Basically, the solution is to do what you've already done which is include the glassfish javax annotation library.
TL;DR use Dagger >= 2.1
Alex is right, but it's better to add JSR250 dependency instead of GlassFish
provided 'javax.annotation:jsr250-api:1.0'
or for the latest gradle plugin:
compileOnly 'javax.annotation:jsr250-api:1.0'
The right answer today is to use a version of dagger which is greater than 2.1 (because of the fix mentioned by @tomrozb is integrated in 2.1)
This happens if your JAVA_HOME points to JAVA version 9 or 10. Switching JAVA_HOME to Java 8 fixes the problem and you will not need that extra dependency.
来源：https://stackoverflow.com/questions/29785530/cannot-find-symbol-class-generated-for-dagger-2