Simplest WorkManager

build.gradle

implementation "androidx.work:work-runtime:2.7.1"
implementation "androidx.work:work-runtime-ktx:2.7.1"

MainActivity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.work.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val constraints = Constraints.Builder()
            .setRequiredNetworkType(NetworkType.CONNECTED)
            .setRequiresBatteryNotLow(true)
            .setRequiresStorageNotLow(true)
            .build()

        val workRequest = OneTimeWorkRequestBuilder<WorkerSample>()
            .setConstraints(constraints)
            .build()

        WorkManager
            .getInstance(this@MainActivity)
            .enqueue(workRequest)

        WorkManager.getInstance(this@MainActivity).getWorkInfoByIdLiveData(workRequest.id)
            .observe(this@MainActivity) { workInfo ->
                Log.d("test", "state ${workInfo?.state}")
            }
    }

}

WorkerSample.kt

import android.content.Context
import android.util.Log
import androidx.work.Worker
import androidx.work.WorkerParameters

class WorkerSample(appContext: Context, workerParams: WorkerParameters): Worker(appContext, workerParams) {

    override fun doWork(): Result {
        Log.d("test", "doWork started")
        Thread.sleep(5000)
        Log.d("test", "doWork finished")
        return Result.success()
    }
    
}