SampleFragment.kt

@AndroidEntryPoint
class SampleFragment : Fragment() {

  @Inject lateinit var sampleWorker : SampleWorkerInterface
  
  ....
  ....
  
  private fun sendData(input : String, onComplete: ((String?) -> Unit)?) {
        sampleWorker.sendData(input) { responseString ->
          // responseString : Workers' result
        }
    }
  
}

SampleWorker.kt

@HiltWorker
class SampleWorker @AssistedInject constructor(
    @Assisted context: Context,
    @Assisted params: WorkerParameters,
    private val sampleRepository: SampleRepository
) : CoroutineWorker(context, params) {

      override suspend fun doWork(): Result {
        super.doWork()
        var result = Result.failure()
        ....
        ....
        return result
    }
}
    
class SampleWorkerImp @Inject constructor(
    private val workManager: WorkManager
) : SampleWorkerInterface {

    override fun sendData( input : String, onComplete: ((String?) -> Unit)? ) {

        OneTimeWorkRequest.Builder(SampleWorker::class.java).apply {
            setConstraints(constraints.build())
            setInputData(Data.Builder().apply {
                putString("KEY_DATA", input)
            }.build())
        }.build().main {
            workManager.enqueue(this)
            with(workManager.getWorkInfoByIdLiveData(id)) {
                observeForever(object : Observer<WorkInfo> {
                    override fun onChanged(work: WorkInfo) {
                        if (work.state == WorkInfo.State.SUCCEEDED
                            || work.state == WorkInfo.State.FAILED
                        ) {
                            onComplete?.invoke(
                                work.outputData.getString("KEY_OUTPUT_DATA")
                            )
                            removeObserver(this)
                        }
                    }
                })
            }
        }
    }

}

SampleWorkerInterface.kt

interface SampleWorkerInterface {
  
    fun sendData( 
      input : String,
      onComplete: ((String?) -> Unit)?
    )
    
}