AsyncTaskと同等の機能をKotlinのCoroutine（コルーチン）で実装

<code kotlin>
import android.os.AsyncTask
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

      Log.i("async","onCreate: ${Thread.currentThread().name}")
      button.setOnClickListener {
          MyAsyncTask().execute()
      }

  }

 inner class MyAsyncTask:AsyncTask<Void,Int,Void>(){

      override fun onPreExecute() {
          Log.i("async","onPreExecute: ${Thread.currentThread().name}")
          super.onPreExecute()
          text.text="onPreExecute"
          Thread.sleep(800)
      }

      override fun doInBackground(vararg p0: Void?): Void? {
          Log.i("async","doInBackground: ${Thread.currentThread().name}")
          for(i in 1..3){
              publishProgress(i)
              Thread.sleep(800)
          }
          return null
      }

      override fun onProgressUpdate(vararg values: Int?) {
          Log.i("async","onProgressUpdate: ${Thread.currentThread().name}")
          super.onProgressUpdate(*values)
          text.text="onProgressUpdate${values[0]}"
      }

     override fun onPostExecute(result: Void?) {
         Log.i("async","onPostExecute: ${Thread.currentThread().name}")
         super.onPostExecute(result)
         text.text="onPostExecute!"
     }

  }

}
　↓
アプリ起動
onCreate: main

ボタン　クリック
onPreExecute: main
doInBackground: AsyncTask #1
onProgressUpdate: main
onProgressUpdate: main
onProgressUpdate: main
onPostExecute: main
<code>