Deprecated code for import android.os.AsyncTask

Question

I have been writing some code and it gave me an error stating that the Async function has been deprecated. I'm trying to work around this but I am lost on which would be the best method to remediate this. Please advise if there is a workaround for the code. I am extracting data from Open Weather maps for may application.

import android.os.AsyncTask
import android.os.Bundle
import android.view.View
import android.widget.ProgressBar
import android.widget.RelativeLayout
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import org.json.JSONObject
import java.net.URL
import java.text.SimpleDateFormat
import java.util.*

class MainActivity : AppCompatActivity() {

    val LAT: String = "1.4854081"
    val LON: String = "14.6618699"
    val API: String = "API FROM OPEN WEATHER REMOVED"

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

        weatherTask().execute()

    }

    inner class weatherTask() : AsyncTask<String, Void, String>() {
        override fun onPreExecute() {
            super.onPreExecute()
            /* Showing the ProgressBar, Making the main design GONE */
            findViewById<ProgressBar>(R.id.loader).visibility = View.VISIBLE
            findViewById<RelativeLayout>(R.id.mainContainer).visibility = View.GONE
            findViewById<TextView>(R.id.errorText).visibility = View.GONE
        }

        override fun doInBackground(vararg params: String?): String? {
            var response:String?
            try{
                response = URL("https://api.openweathermap.org/data/2.5/weather?lat=$LAT&lon=$LON&units=metric&appid=$API").readText(
                    Charsets.UTF_8
                )
            }catch (e: Exception){
                response = null
            }
            return response
        }

        override fun onPostExecute(result: String?) {
            super.onPostExecute(result)
            try {
                /* Extracting JSON returns from the API */
                val jsonObj = JSONObject(result)
                val main = jsonObj.getJSONObject("main")
                val sys = jsonObj.getJSONObject("sys")
                val wind = jsonObj.getJSONObject("wind")
                val weather = jsonObj.getJSONArray("weather").getJSONObject(0)

                val updatedAt:Long = jsonObj.getLong("dt")
                val updatedAtText = "Updated at: "+ SimpleDateFormat("dd/MM/yyyy hh:mm a", Locale.ENGLISH).format(Date(updatedAt*1000))
                val temp = main.getString("temp")+"°C"
                val tempMin = "Min Temp: " + main.getString("temp_min")+"°C"
                val tempMax = "Max Temp: " + main.getString("temp_max")+"°C"
                val pressure = main.getString("pressure")
                val humidity = main.getString("humidity")

                val sunrise:Long = sys.getLong("sunrise")
                val sunset:Long = sys.getLong("sunset")
                val windSpeed = wind.getString("speed")
                val weatherDescription = weather.getString("description")

                val address = jsonObj.getString("name")+", "+sys.getString("country")

                /* Populating extracted data into our views */
                findViewById<TextView>(R.id.address).text = address
                findViewById<TextView>(R.id.updated_at).text =  updatedAtText
                findViewById<TextView>(R.id.status).text = weatherDescription.capitalize()
                findViewById<TextView>(R.id.temp).text = temp
                findViewById<TextView>(R.id.temp_min).text = tempMin
                findViewById<TextView>(R.id.temp_max).text = tempMax
                findViewById<TextView>(R.id.sunrise).text = SimpleDateFormat("hh:mm a", Locale.ENGLISH).format(Date(sunrise*1000))
                findViewById<TextView>(R.id.sunset).text = SimpleDateFormat("hh:mm a", Locale.ENGLISH).format(Date(sunset*1000))
                findViewById<TextView>(R.id.wind).text = windSpeed
                findViewById<TextView>(R.id.pressure).text = pressure
                findViewById<TextView>(R.id.humidity).text = humidity

                /* Views populated, Hiding the loader, Showing the main design */
                findViewById<ProgressBar>(R.id.loader).visibility = View.GONE
                findViewById<RelativeLayout>(R.id.mainContainer).visibility = View.VISIBLE

            } catch (e: Exception) {
                findViewById<ProgressBar>(R.id.loader).visibility = View.GONE
                findViewById<TextView>(R.id.errorText).visibility = View.VISIBLE
            }

        }
    }
}

this might help https://stackoverflow.com/a/58900195/1731626 — Sergio, Jun 23 '20 at 18:49

Sergio · Answer 1 · 2020-06-23T19:47:50.433

You can implement something similar to AsyncTask using Kotlin coroutines:

class AsyncTaskViewModel : ViewModel() {
    
    fun <R> execute(
            onPreExecute: () -> Unit,
            doInBackground: () -> R,
            onPostExecute: (R) -> Unit
    ) = viewModelScope.launch {
        onPreExecute()
        val result = withContext(Dispatchers.IO) { // runs in background thread without blocking the Main Thread
            doInBackground()
        }
        onPostExecute(result)
    }
}

In Activity to retrieve AsyncTaskViewModel :

val vm: AsyncTaskViewModel by lazy { ViewModelProvider(this)[AsyncTaskViewModel::class.java] }

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

    vm.execute(onPreExecute = {
        //...
    }, doInBackground = {
        //...
        "Response" // value to return
    }, onPostExecute = {
        // ... here "it" contains data returned from "doInBackground"
    })
}

If you don't want to use ViewModel, just create an extension function on on CoroutineScope and call it from Activity:

// extension function:

fun <R> CoroutineScope.executeAsyncTask(
        onPreExecute: () -> Unit,
        doInBackground: () -> R,
        onPostExecute: (R) -> Unit
) = launch {
    onPreExecute()
    val result = withContext(Dispatchers.IO) { // runs in background thread without blocking the Main Thread
        doInBackground()
    }
    onPostExecute(result)
}


// Call it from Activity: 

lifecycleScope.executeAsyncTask(onPreExecute = {
    // ...
}, doInBackground = {
    //...
    "Response" // value to return
}, onPostExecute = {
    // ... here "it" contains data returned from "doInBackground"
})

To use viewModelScope and lifecycleScope add next lines to dependencies of the app's build.gradle file:

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$LIFECYCLE_VERSION" // for viewModelScope
implementation "androidx.lifecycle:lifecycle-runtime-ktx:$LIFECYCLE_VERSION" // for lifecycleScope

Deprecated code for import android.os.AsyncTask

1 Answers1