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Replace Dagger-Android with Hilt and remove Kapt

Open cbeyls opened this issue 1 month ago • 1 comments

Hilt is an annotation processor built on top of Dagger which allows to remove all the Android dependency injection boilerplate code (currently around 900 lines) by writing it for us.

Hilt can use KSP instead of Kapt so Kapt can be completely removed from the project. Kapt is slow, deprecated and has a few compatibility issues. Removing Kapt will improve build times since no Java stubs have to be generated for Kotlin classes anymore (Note that KSP also processes annotations in Java classes so it can completely replace Kapt).

  • Remove all modules related to manual dependency injection configuration.
  • Rename AppModule to StorageModule since it now only contains configuration to retrieve the DataBase and SharedPreferences.
  • Annotate all entry points (Activities, Fragments, BroadcastReceivers and Services) with @AndroidEntryPoint.
  • Annotate all injected ViewModels with @HiltViewModel and replace the custom ViewModel Factory with the default one (which integrates with the one generated by Hilt).
  • Add a public field to allow overriding the default ViewModelProvider.Factory in BaseActivity in tests.
  • Annotate tested Activities with @OptionalInject since Activity tests currently rely on the Activities not being injected automatically.
  • Annotate injected Context arguments with @ApplicationContext. Hilt provides the Context binding automatically but requires to specify if the Application or Activity Context is wanted.
  • Add WorkManager Hilt integration so all Workers are injected by Hilt automatically using HiltWorkerFactory.
  • Lazily initialize WorkManager in TuskyApplication.
  • Remove Kapt and Kapt workarounds.
  • ~~Remove toolchain configuration for Java 21. Toolchains force the Java bytecode to match the JDK version used to build the project, and apparently Hilt doesn't run inside the toolchain so cannot process the source code if the JDK version of the toolchain is higher than the JDK used to run Gradle. And configuring a toolchain for an older Java version causes other issues. Removing toolchains configuration doesn't prevent the project from being built using JDK 21 or more recent versions but allows to build the project using older JDKs as well.~~ Added a fix to allow Hilt to properly use the JDK toolchain.
  • ~~Set the Java and Kotlin bytecode target to Java 17. The standard bytecode target for Android projects is usually Java 8 or 11 (any higher version doesn't provide any benefit but may cause compatibility issues). However, since the app currently uses a library built against Java 17 bytecode (networkresult-calladapter), it needs to target at least Java 17 bytecode as well.~~
  • Update the Dagger 2 URL in the licenses screen. Hilt is part of Dagger 2 so the label wasn't changed.

cbeyls avatar May 05 '24 16:05 cbeyls

@Goooler I agree that removing the toolchain is a different discussion and should be part of another PR, so I added it back.

The problem was that Hilt did not use JDK of the toolchain, thus defeating the purpose of using a toolchain. Fortunately I now found a fix to force Hilt to use the toolchain as well:

    tasks.withType(JavaCompile).configureEach {
        javaCompiler = javaToolchains.compilerFor {
            languageVersion = JavaLanguageVersion.of(21)
        }
    }

The project can again be built by running Gradle from any JDK version.

cbeyls avatar May 07 '24 13:05 cbeyls