Hilt ‐ Scoping with just @Singletion annotation and without @SingletonComponent annotation - devrath/DroidDi GitHub Wiki

Observation

• Observe that I have annotated the implementation class HiltAnalyticsService with @Singleton.
• Note we do not have a @Singleton component.
• Still not that when you rotate the Activity the Injected class is not re-instantiated which can be seen in the address printed.

Output

// When activity is loaded for the first time 
HiltAnalyticsService class is built
// Click on the Button to call the injected reference in activity for the first time
Reference address:-> 72836706
// Click on the Button to call the injected reference in activity for the second time
Reference address:-> 72836706
// When you rotate the screen 
// Click on the Button to call the injected reference in activity for the third time
Reference address:-> 72836706

Implementations

HiltAnalyticsService.kt

@Singleton
class HiltAnalyticsService @Inject constructor() {
    init {
        PrintUtils.printLog("HiltAnalyticsService class is built")
    }

    fun logAnalytics(data : String) {
        PrintUtils.printLog("Reference address:-> $data")
    }
}

Activity

MyActivity.kt

@AndroidEntryPoint
class HiltScopingActivity : AppCompatActivity() {

    private lateinit var binding: ActivityHiltScopingBinding

    @Inject lateinit var imageProcessingService : ImageProcessingService

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityHiltScopingBinding.inflate(layoutInflater)
        setContentView(binding.root)
        setOnClickListeners();
    }

    private fun setOnClickListeners() {
        binding.apply {
            notASingleTonId.setOnClickListener {
                // Not a singleton
                val code = imageProcessingService.hashCode().toString()
                imageProcessingService.processImage(code)
            }
        }
    }
}