AsyncTask in Android with Kotlin

Question

How to make an API call in Android with Kotlin?

I have heard of Anko . But I want to use methods provided by Kotlin like in Android we have Asynctask for background

Answer 1

This is how I do in my projects to avoid memory leaks:

I created an abstract base Async Task class for Async loading

import android.os.AsyncTask

abstract class BaseAsyncTask(private val listener: ProgressListener) : AsyncTask() {

    interface ProgressListener {
        // callback for start
        fun onStarted()

        // callback on success
        fun onCompleted()

        // callback on error
        fun onError(errorMessage: String?)

    }

    override fun onPreExecute() {
        listener.onStarted()

    }

    override fun onPostExecute(errorMessage: String?) {
        super.onPostExecute(errorMessage)
        if (null != errorMessage) {
            listener.onError(errorMessage)
        } else {
            listener.onCompleted()
        }
    }
}

USAGE:

Now every time I have to perform some task in background, I create a new LoaderClass and extend it with my BaseAsyncTask class like this:

class LoadMediaTask(listener: ProgressListener) : BaseAsyncTask(listener) {

    override fun doInBackground(vararg params: Void?): String? {

        return VideoMediaProvider().allVideos
    }
}

Now you can use your new AsyncLoader class any where in your app.

Below is an example to Show/Hide progress bar & handle Error/ Success scenario:

   LoadMediaTask(object : BaseAsyncTask.ProgressListener {
            override fun onStarted() {
                //Show Progrss Bar
                loadingBar.visibility = View.VISIBLE
            }

            override fun onCompleted() {
                // hide progress bar
                loadingBar.visibility = View.GONE
                // update UI on SUCCESS
                setUpUI()
            }

            override fun onError(errorMessage: String?) {
                // hide progress bar
                loadingBar.visibility = View.GONE
                // Update UI on ERROR
                Toast.makeText(context, "No Videos Found", Toast.LENGTH_SHORT).show()
            }

        }).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)